In Awassi ram lambs in Iraq, puberty — as defined by the
presence of spermatozoa in the testes and epididymides — is attained during the
first half of the eighth month at a weight of 30-37 kg.
At Abu-Ghraib in Iraq, Ghannam, Madhat and El-Shobokshy (1978a) and Ghannam, Madhat and Eltawil (1978b) examined the onset of sexual maturity and the development of the sex organs of 18 male Awassi lambs which from the age of 107-113 days and a weight of 15.0-22.5 kg were kept on a ration of lucerne and concentrates supplying normal requirements of energy and protein, and of 18 others on a ration containing 20 percent more protein. Three lambs of each group were slaughtered at the age of 133 days, followed by three more of each group slaughtered at monthly intervals from 171 to 325 days. After slaughter the weight of the reproductive organs and endocrine glands was recorded, and a section of each gland was studied histologically. The epididymis was examined microscopically for the presence of spermatozoa, and the fructose content of the seminal vesicles was estimated.
The increase in protein intake of 20
percent above the normal requirements had no influence on the age at which
sexual maturity was attained. There was no detectable difference between the
two groups in the average weights of body, endocrine glands and reproductive
organs at the various ages, save for an increase in
the weight of the seminal vesicles and their secretory activity at seven months
of age in the group on the higher protein plane.
The weight of the testicles increased threefold from seven to
eight months of age. At eight months it represented 29 percent of the adult
weight. There was little change in the weight of the testes at nine months, but
at ten months a greater weight increase occurred, bringing their weight up to
51 percent of the adult weight.
The average weight of the epididymis increased similarly. At
eight months it was twice the seven-month weight, representing 30 percent of
the adult weight, and at ten months it attained approximately 45 percent of the
adult weight.
The weight of the seminal vesicles markedly increased from
seven to eight months, at the latter age coming to twice their seven-month
weight and representing 44 percent of the adult weight. From eight to eleven
months the weight increased almost linearly to 85 percent of the adult weight.
The pituitary, adrenals and thyroid increased gradually in
weight until the age of seven months. At eight months the weight of all three
glands, but especially of the thyroid, showed a rapid increase. At nine months
the weight of the pituitary and adrenals dropped, while that of the thyroid
continued its marked increase, to decline only at 11 months.
There was no difference in weight between the left and the
right testes. The growth of the testes and epididymides at different ages was
as shown in Table 3-1.
Awassi ram lambs have a well-defined prepubescent period. In
all testes examined at 132-134 days of age, the seminiferous tubules were
non-canalized cords, their lining consisting of large genocytes, with
relatively large nuclei, and of small supporting cells. The genocytes were
located in the centre and the supporting cells around the periphery of the
cords.
At 169-173 days a
distinct lumen appeared in the majority of the seminiferous tubules. The
diameters of the tubules were much larger and the mitotic activity of the
genocytes was more in evidence than at the previous test age.
At 232-235 days
and higher ages, all stages of spermatogenesis were evident in the majority of
the seminiferous tubules and spermatozoa were present in the cauda of the epididymis. As the transit of
spermatozoa through the epididymis of the râm takes about 11-15 days, sexual maturity was attained during the
first half of the eighth month.
The growth
pattern of the endocrine glands indicated an activation of the pituitary,
thyroid and adrenals at seven to eight months, followed by a declining phase of
activity at nine months of age. The endocrinological age of sexual maturity, as
determined by the peak of the fructose content of the seminal vesicles and the
presence of elongated spermatids in the seminiferous tubules, sets in about
three weeks before spermatogenesis. At the age of seven months the weight of
the seminal vesicles and the content and concentration of fructose were
considerably larger in the group on the higher protein level of nutrition than
in the control group; this was the only notable difference between the two
groups. At eight months the content and concentration of fructose in the
seminal vesicles of both groups significantly exceeded that obtaining at other
ages, but at nine months a sharp decline occurred and at eleven months the
fructose content and concentration were significantly lower than in adult rams.
In Lebanon the
onset of sexual maturity in Awassi ram lambs occurred at 140-190 days, two
months earlier than in Iraq, but at a similar body weight (29-36 kg). Barr (1969) studied the growth and
development of the testes and epididymides of male Awassi lambs kept on a fair
plane of nutrition from birth to the age of 48 weeks. At interváls of four weeks two lambs were weighed,
slaughtered and their sex organs removed for examination. (See Figs 3-1 to
3-4.)
Until the age of 12 weeks the
growth rate of the testes and epididymides was slow. Thereafter their weights
markedly increased, their rates of growth exceeding that of the body. At the
age of one week the
weight of the testis was 2.87 g and
of the epididymis 1.62 g on
average. At 12 weeks the average weights of the two organs had increased to
16.52 and 4.57 g, and at 20 weeks to 131.0 and 12.8 g, respectively. The average length of the
testis was 1.62 cm and its breadth 0.75 cm at the age of one week, 3.7 and 2.0
cm, respectively, at 12 weeks, and 8.87 and 5.00 cm at 20 weeks.
Figure 3-1. Testicular slice from a 1 -week-old Awassi ram lamb (G-gametocytes). (Source: Barr, 1969)
Figure 3-2. Testicular slice from a 20-week-old Awassi ram lamb (SG-spermatogonia;
Sp-spermatazoa). (Source: Barr, 1969)
Figure 3-4. Epididymal slice from a 20-week-old Awassi ram lamb
(Sp-spermatozoa). (Source: Barr, 1969)
The epididymides
reached maturity at 12 weeks; at this age their previously high columnar epithelium
had lowered and the pseudo-stratified epithelium appeared. Until the age of 16
weeks the testes remained in an infantile state. At this age the gametocytes
had almost completely disappeared and spermatogonia made their appearance in
the sex cords. At 20 weeks the proliferation stage and spermatogenesis
commenced and spermatozoa were found in the seminiferous tubules and the lumina of the epididymal coils.
The author
concluded that under conditions in Lebanon, male Awassi lambs should be
separated from the females at not later than five months of age and that they
could be used for service at seven months.
Well-fed male
Awassi lambs of the improved dairy type first show signs of sexual desire at
weaning time at the age of three or four months, when they weigh 40-50 kg. At
five to six months they produce normal spermatozoa, and at eight months, when
they have reached a weight of 90-110 kg, they can be employed for service.
After weaning, the Awassi ram lambs
of the improved dairy type, reserved for breeding, are pastured for four or
five months until June. From July to the end of September they are penned up
with free access to hay of which they consume approximately 500 g a day. In addition to grazing or hay,
they receive unlimited quantities of concentrates until the age of l½ years.
The length of the
breeding season varies among Awassi flocks according to the flock-master's
decision to restrict lambing to a relatively short period or to extend it over
eight months or even the whole of the year, and to have their ewes lamb only
once a year or more than once. A teaser ram, provided with an apron, is
employed to pick out the ewes in heat. The rams serve in the morning before the
ewes leave for pasture, and in the evening after their return to the fold. If
many ewes come into heat simultaneously, adult rams may also be used for
service at adequate intervals during the day. Between the first two services an
interval of ten minutes is sufficient. If more than two services are required
of a ram, intervals of half an hour are recommended. Young rams, seven to eight
months old, should not serve more than three or four times a week.
Shepherds of
Awassi sheep hold that it is easier to train a ram than a ewe. Every stud ram
is given a name early in life and he is trained to come to the sheepman when
called by name and to leave again when told to. This training is particularly
useful at breeding time when the ewes in heat have to be served according to
the mating plan worked out prior to the breeding season. In hand-mating the
ewes located by the teaser are trapped in a milking stand. The rams appointed
to serve are called one after the other. The ram whose turn has come approaches
the ewe and endeavours to push her fat tail with his right foreleg upwards and
sideways while mounting. This often requires several attempts. If the fat tail
is too heavy to be moved with the leg, the ram dismounts and uses his chest to
lift the ewe's tail up. To facilitate service and not to tire the ram, the
sheepman will assist by keeping the ewe's tail out of the way. On its
introduction into the vagina the penis of the Awassi ram is not horizontal as
it is more or less in thin-tailed breeds, but is curved bow-like downward
(Hinrichsen & Lukanc, 1978). After service the ram is told to return to his
pen.
From October on,
when the main mating season (during which approximately 85 percent of the ewes
are served) is over, the rams go out to pasture with the pregnant ewes. For the
ewes not yet in lamb, hand-mating is replaced by pasture-mating. In commercial
flocks several rams may accompany them. In stud flocks, where it is important
to know the sire of every lamb, a single ram, usually the best one, goes out with the unfertilized ewes. In addition to the
pasturage, the rams are given 500 g of
concentrates a day.
An outstanding ram
may be employed in the same or other flocks until its death. One improved ram,
whose dam had excelled in both fecundity and milk production, still served in
an experimental flock at the age of 14 years without showing any signs of
deterioration in libido or fertility. His twin brother, too, was employed in a
stud flock to a very great age. Generally, however, rams are culled when they
are six or seven years old.
The principal breeding season of
Awassi sheep is in summer. However, in improved flocks breeding begins one or
two months earlier than in the flocks of the Arab bedouin and fellahin. To a
large extent this may be attributed to a rigorous selection for milk since the
lactation yield of ewes lambing early in the cool,
rainy winter season is less depressed by the heat and drought of the summer
than that of late-lambing ewes, a large part of whose lactation period
coincides with the summer months.
Figure 3-5 a andb. Seminiferous tubules of an unimprpved Awassi
ram in April. (Source: Volcani,
1957)
Figure 3-6 a and b.
Seminiferous tubules of an
unimproved Awassi ram in June and July. (Source:
Volcani, 1957)
In unimproved
Awassi rams an examination of the testes reveals maximum spermatogenic activity
during the summer months, signs of degeneration of the seminiferous tissue in
autumn, and regeneration in spring (Volcani, 1953, 1957). The mean weight of
the testes of unimproved Awassi rams is 140 g, and of the epididymis 23 g.
During the month of April the mean diameter of the seminiferous tubules is 105 μ, in June and July 195-260 μ, in September 140-150 μ, and in December close to the
June and July figures.
In April the
seminiferous tubules are lined with a single layer of epithelial cells with
acidophile material in the centre, while the connective material between them
is sparse. In this month the tubules show very little activity or none at all
(Fig. 3-5 α and
b).
In June and July
the number of all epithelial cell layers as well as of
the sperm cells in the Sertoli cells and the centre of the tubules is large.
The hollow of the tubules does not contain round cells, but is filled with the
acidophile secretion enveloping the tails of the ripening sperm cells. The
connective tissue between the tubules is highly developed (Fig. 3-6 α and b).
In September spermatogenetic
activity is reduced. The cell layers in the tubules show a lack of organization
and the presence of primary spermatocytes, but few other forms. Mature sperm
cells are seen only around the hollow of the tubules. The latter display a
marked degree of destruction, with sparse interstitial tissue (Fig. 3-7 α and b).
In December the
destruction has progressed still further. The division is negligible and there
are very few sperm cells or none at all. The lack of organization in the
various layers is most conspicuous. There are numerous round cells in the hollow
of the tubules and the connective tissue is well developed (Fig. 3-8 α and b).
Figure 3-8 a and b.
Seminiferous tubules of an
unimproved Awassi ram in December. (Source:
Volcani, 1957)
In the epididymis
no seasonal differences parallel to those that occur in the testes between the
months of high and low spermatogenic activity are found in the diameter of the
tubules or the height of the epithelium. In June and July numerous sperm cells
are arranged vertically. In September the vortexes are sparser and in December
only a few, partly degenerated sperm cells are found. Again, in July secretion
is copious, but in September it is moderate to negligible.
In
the histological structure of the connective tissue between the seminiferous
tubules there are no phenomena parallel to those characteristic of the
different seasonal activities of the testes (Volcani, 1953).
The level of
androgens, indicative of sexual activity and a balance between the
gonadotrophins, is closely related to fructose and citric acid concentrations
as well as to semen voume (Mann & Parsons, 1947; Humphrey & Mann,
1949). Rams in an unimproved bedouin flock pastured with the ewes throughout
the year, and improved Awassi rams, either completely isolated from ewes,
separated from them merely by a fence or pastured with them throughout the year
— just as in the unimproved flock but with an additional ration of hay and
concentrates — all showed the lowest fructose and citric acid concentrations in
the semen from March to June. The highest citric acid
concentrations, about twice as large as the lowest, occurred from September to
November. Peak fructose concentrations varied. In the two flocks, one
unimproved and one improved, in which the rams were pastured with the ewes
during the whole year, the maximum concentration was observed in October and
November, and in the rams completely isolated or fenced off from the ewes, in
July and August. The presence of ewes in heat causes a more pronounced
difference between peak and minimum fructose concentrations than does isolation
of the rams. The practice of introducing the rams into the flock after a period
of separation in order to obtain a high frequency of oestrus in a short span of
time early in the season makes the peak of fructose concentration appear
earlier than it does in rams kept continuously with the ewes or in those fenced
off from them (Amir, 1964; Amir & Volcani, 1965a).
With regular semen
collections, the volume of the ejaculate is largest in autumn and smallest in
spring. From the fructose and citric acid concentrations in the semen and the
volume of the ejaculate, it may be concluded that the androgenic activity of
adult Awassi rams attains its highest level in autumn and its
lowest in spring (Amir & Volcani, 1965b).
In rams completely
isolated from ewes, the highest sperm density obtains from March to June and
the lowest from August to January. In rams fenced off from ewes or pastured
together with them, fluctuations in sperm density are greater than in isolated
rams, with the maximum level occurring from March to May and the minimum in the
breeding season from June to November.
Again, in isolated
rams the maximum sperm number, as calculated from the volume and density of the
ejaculate, is found from August to January and the least from March to June. In
unimproved Awassi rams that run with the ewes throughout the year, a converse
seasonal pattern is observed, with the highest sperm number in spring and the
lowest in autumn. In improved rams, fenced off from, or running with, the ewes,
there are marked fluctuations in sperm number over the year.
Sperm motility is
highest in summer and autumn, and lowest, generally, in winter. Occasionally a
reduction in sperm motility may occur in bedouin rams in summer too, probably
owing to poor pasturage and a Vitamin A deficiency (Amir
& Volcani, 1965c).
In the semen of
Awassi rams isolated from ewes, highly positive correlations exist between
fructolysis and semen density and also between fructolysis and initial fructose
concentration, while density and initial fructose concentration show a highly
negative correlation. Amir and Volcani (1965d) believe that the seasons of the
year do not directly influence the fructolytic activity of the sperm cells of
Awassi rams, but that this depends on the seasonal changes in sperm density and
initial seminal fructose concentration.
The oxygen
consumption of the spermatozoa rises in the summer and falls in winter and
spring. The decrease in the respiratory activity of the spermatozoa, without
influence on their motility, seems to be a result of the low winter and high
spring temperature prior to shearing, both of which may inhibit the cytochrome
oxidase of the cells.
To ascertain
whether or not some of the seasonal changes in the spermatogenic activity of
the testes observed in unimproved rams are owing to malnutrition and Vitamin A
deficiency during the dry period of the year, Amir and Volcani (1965e) examined
the spermatogenic activity of two improved Awassi rams kept on a high plane of
nutrition by regular sperm collection once a week. In the course of two years
the rams were subjected to exhaustion tests four times a year during the months
of July, October, January and April. On the test days 13-16 semen collections
were made within two or three hours. The maximum number of spermatozoa was
obtained in October and the least in January, while the fructose and citric
acid contents of 13 ejaculates rose in October and November and decreased in
March and April. The lowest mean motility of the spermatozoa occurred in
January.
Considering a
lapse of time of approximately two months between the onset of the
spermatogenic cycle and the resultant ejaculate, the authors concluded that the
maximum spermatic reserves obtained in October resulted from a pronounced
spermatogenic activity in August and the minimum reserves in January from that
of November. Hence, the seasonal fluctuations observed in spermatogenic
activity appear to be similar in unimproved and improved Awassi rams, albeit
smaller in adult improved rams on a high plane of nutrition than in unimproved
males pastured throughout the year.
In both the
unimproved and improved Awassi rams, irrespective of the level of nutrition,
regeneration of the seminiferous tubules apparently begins in winter under the
influence of increasing daylight. The first signs of this were noticed in the
exhaustion tests in March and April. Regeneration continues until the longest
days, resulting in the collection of the maximum number of spermatozoa in
September. With decreasing daylight, degeneration leads to the lowest level of
spermatogenesis in December, followed by the minimum number of spermatozoa in
February.
The semen does not
show the largest fructose and citric acid contents in the month of highest
spermatogenic activity, nor the smallest contents at
the lowest level of activity. Rather, the fructose and citric acid contents of
the semen reflect maximum androgenic activity in October-November, and lowest
in March-April. It seems that the FSH
secretion influencing spermatogenesis increases and decreases with the
changes in daylight length, whereas the changes in LH secretion influencing androgenic
activity occur three or four months later.
Notwithstanding
the observed fluctuations in their sexual activity owing to season or
management, Awassi rams may be employed for
breeding at any economically advantageous time of the year. At Abu-Ghraib in Iraq, Juma and Dessouky (1969) examined 147 ejaculates collected at fortnightly
intervals from four fat-tailed and three docked five-year-old Awassi rams in
the course of a year to study the effects of season and docking on volume, mass
activity, individual motility, sperm concentration, sperm number, methylene
blue reduction time, the hydrogen-ion concentration (pH) and the percentages of dead and
abnormal sperm (Fig. 3-9 and Table 3-2). The number of ejaculates collected
from undocked rams varied between five and ten, and from docked rams between four
and seven a month. All rams were born within a week and received the same feed
and management.
Figure 3-9 Monthly variation in semen characteristics of undocked and docked Awassis rams in Iraq. (Source: Juma & Dessouky, 1969)
In both groups the
volume of the ejaculates was lowest during winter and highest in the undocked
rams in autumn and in the docked ones in summer. Mass activity and individual
motility were not affected by docking; the lowest estimates were obtained
during winter and the highest from May to September. In both groups the
concentration and number of spermatozoa also showed their highest levels from
May to September. Docking increased sperm production, in particular in summer.
The authors suggest that the superiority in this respect of the docked rams may
be because of anatomical or metabolic changes, such as the thickness of
subcutaneous fat and the ability of maintaining a lower body
temperature and respiration rate. In both groups the percentages of abnormal
and dead spermatozoa were highest in winter and lowest in summer, but in the
semen of the docked rams, as a result of their superior heat regulation, the
percentage of abnormal cells in spring and summer was only half that of the
intact animals. The pH of the
semen of both undocked and docked rams maintained practically the same level
throughout the year.
Somewhat different
results from a study of the characteristics of 155 ejaculates from four
fat-tailed sheep and of 121 ejaculates from four docked two-year-old Awassi
rams, collected once a week over a period of a year, have been obtained by
Majid et al. (1977) in
Iraq. The rams were kept during the trial in a semi-open pen and fed green
lucerne or hay ad libitum, without pasture or concentrates. Docking
attributed to a slight, insignificant increase in semen volume; the effect of
month on volume, as shown in Table 3-3, was also insignificant.
The highest sperm
concentration in the semen of the intact rams was in March and in that of the docked
rams in November; in both groups the lowest concentration was in December. Again,
the highest motility in the semen of both groups was recorded in March, and the
lowest in the intact rams in February and in the docked ones in December. The
semen of the docked rams was superior in mass activity and sperm concentration
to that of the undocked ones.
Docking had no
significant effect on the fructose and ascorbic acid contents of the semen. The
highest fructose contents were observed during October and the lowest during
August, the highest ascorbic acid contents during the late summer and autumn
and the lowest during March. Nevertheless docking improved the quality of the
semen, as indicated by the significant pH reduction. Generally, the semen was of the highest quality in the
period from March to June. The pH tended
to drop in the intact Awassi rams from April to June, and in the docked rams
from October to November.
After weaning, the female lambs
accompany the ewes in lamb to pasture. During the first week, when they are not
yet used to grazing, they are still given unlimited quantities of hay and concentrates at night; thereafter, until the beginning of
the rainy season in November, only concentrates. After the first rains the
lambs remain in the shed where they receive 1 kg of concentrates, 300 g of hay and an unlimited quantity
of straw each day until there is sufficient new pasturage, generally in
January. With the renewed grazing, their ration is reduced to 500 g of concentrates a day.
Female lambs born
early in the season come into heat in August at the age of nine or ten months,
and are served or inseminated at the first heat. Those in which natural oestrus
is delayed are given a hormone treatment in September or October, on
condition that they weigh not less than 50 kg. About 70 percent of the young ewes
lamb as yearlings, the rest at the age of two years.
From January on
the yearlings that conceived in August, September or October are prepared for
their first lactation by a daily ration of 800-900 g of concentrates in addition to natural or
sown pasture.
In unimproved
Awassi flocks the ewes lamb for the first time at the age of two years or more;
lambing at the age of one year is practically unknown. In improved flocks the
same condition continued for many years. Hirsch (1933) reported that in the early 1930s in a well-managed
flock of a communal settlement and in a year of rich pastures, the female lambs
came into heat prematurely and lambed at the age of one year, with the result
that their growth was retarded. In the following years the rams were therefore
separated from the female lambs with which they had previously gone to pasture.
Eventually, as a
result of improved feeding and management and selection for high milk yields,
the age of first lambing was advanced by a year in part of the young females
without detriment to their growth. In 1942, only two of 158 registered ewes, or
1.26 percent, lambed as yearlings, but in 1953 already 165 of 916 registered
ewes (or 18.02 percent) lambed as yearlings (Finci, 1957). In a large flock
belonging to a communal settlement, the first instances of the lambing of
yearlings occurred in two isolated years, 11 and 19 years after the foundation
of the flock. However, 22 years after its establishment, lambing at one year of
age became a regular feature, rising, with annual fluctuations, to a peak of
one-third of all first-lambing ewes. During a period of 30 years, from 1929/30
to 1959/60, when the use of hormones to induce early oestrus had not yet been
introduced, the percentage of lambings of yearlings within the total number of
first lambings in this flock was as shown in Fig. 3-10.
Figure 3-10. Number of lambings of yearling ewes as a
percentage of total number of first lambings. (Source:
Epstein & Herz, 1964)
In one flock,
newly established with 250 two-month-old lambs purchased from four different
farms, 169 (or 67.6 percent) lambed as yearlings (Finci, 1957). In another,
medium-sized flock, set up in 1953 at an agricultural school in the south of
Israel with foundation stock of highly improved two-month-old lambs, 85 percent
lambed for the first time at the age of one year without hormone application
(Epstein & Herz, 1964). In 17 registered flocks, the mean age of yearlings
at lambing was 151/2.months. The distribution of their
ages on the day of parturition is shown in Table 3-4.
Age |
Yearlings |
|||
Number |
% |
|||
20-32 |
6 |
1.54 |
||
33-62 |
39 |
10.02 |
||
63-92 |
110 |
28.28 |
||
93-122 |
131 |
33.68 |
||
123-152 |
84 |
21.59 |
||
153-182 |
19 |
4.89 |
||
Total |
389 |
100.00 |
||
Source: Finci, 1957 |
||||
In unimproved Awassi flocks the breeding season is to a
large extent determined by the conditions of pasture. The ewes come into heat
only when spring and summer grazing has restored the weight lost in the preceding
period of drought and has brought them back to a fair condition. The mating
season lasts approximately from June to September, so that lambs are born when
there is enough pasture for the ewes in milk and for the young lambs.
Occasionally oestrus occurs earlier in the season and since the rams are
running with the ewes all year round, lambs may be born before the pastures
provide sufficient nourishment for the ewes to have enough milk and for their
lambs to develop normally. Nor is oestrus at the usual breeding time always a
success, for delayed or scanty winter rains and poor pasture growth in spring
may be calamitous for the whole flock, but especially for ewes in lamb or in
milk, young lambs and aged animals.
In 391 adult
Awassi ewes of an experimental flock in Israel, the first oestrus in the mating
season was observed toward the end of June, rising to a peak in the first half
of August, to fall again by the first week of October, after which no animal
with first oestrus was left (Table 3-5).
In Lebanon, in an
experimental flock of 50 well-fed Awassi ewes accompanied by mature teaser rams
which were changed at weekly intervals, oestrus reached its peak with regular
cycles in August and September, but was still maintained on a fairly high level
until December. From January to April the heats markedly decreased in number,
and from May to July ceased altogether. The number of heats for each ewe ranged
from five to 15, with an average of ten. The length of the mating season varied
between 150 and 255 days, with an average of 165 days (Barr, 1968).
In Israel, the
sexual season of 11 improved Awassi ewes, two-and-a-half to four-and-a-half
years old, which were not mated for a whole year, was studied by Amir (1964)
and Amir and Volcani (1965a). The animals were kept on a high plane of
nutrition and their pens were lit at night in accordance with general practice
in improved Awassi dairy flocks in Israel. The ewes exhibited an average of 12
(9-15) heats from June to April. The authors suggest that the sexual season of
the improved Awassi ewe may be even longer than that found in their trial since
accurate observation began only a month after the beginning of the normal
breeding season. It would therefore appear that in conditions of good feeding
and sound management, a large percentage of Awassi ewes may be bred practically
throughout the year. This may be attributed to the origin of the Awassi in a
subtropical region where the seasonal variation in daylight length is
relatively small.
In stud and
commercial dairy flocks of improved Awassi sheep, the breeding season generally
lasts from May to December. The spread of lambing in adult and yearling ewes
over two-thirds of the year avoids the excessive burden of work of a restricted
lambing period. From January to April the rams are separated from the ewes and
service is discontinued, although some females may come into heat during this
time. Discontinuance of mating is due to the undesirability of having lambs
born during the hot season of the year when the young lambs do not thrive well,
digestive troubles are frequent,
and the milk production of the ewes is adversely affected by the heat. However,
there are also many commercial flocks in which the rams accompany the ewes for
a major part of the year and are separated from them for only a month before
the beginning of the mating season in the middle of June or in July, depending
on local conditions.
The onset of the
breeding season of Awassi ewes may be advanced by the introduction of rams,
until then separated from the females, into the flock of ewes when their
ovaries are already active. The ewes react to the sudden exteroceptive stimulus
aroused by the presence of the males by coming into heat after a short time. A
study in a number of Awassi flocks extending over several years has shown that
there are two main waves of oestrus following the introduction of rams, each
lasting from two to six days. The peak of the first wave occurs about the
eighteenth day and that of the second one on the twenty-fifth to twenty-sixth day
of the presence of the rams. Between the two peaks there is an interval of
seven to ten days. The incidence of the first oestrus following the joining of
both sexes increasingly lessens with the growing interval between the
introduction of the rams into the flock and the onset of the natural breeding
season (Eyal, 1958).
No statistically
significant trend for the onset of oestrus to be centred around
a certain time of day was found by Schindler and Amir in 403 Awassi ewes
observed from August to January in three consecutive years (Table 3-6). But in
an Awassi flock in Lebanon, 67 percent of heats were detected in the morning
and 33 percent in the afternoon (Barr, 1968).
In the same Awassi
flock in Lebanon, the length of the oestrous cycle in 288 normal heats varied
between 15 and 20 days, with an average of 18 days. The duration of cycles was
regular in August and September, becoming irregular toward the end of the
breeding season (Barr, 1968).
In improved Awassi
dairy ewes in Israel, the mean length of the oestrous cycle has been reported
by different workers to be 17.4 days in August and 17.3 in September. In 11
ewes that were not mated for a whole year, the average duration of the oestrous
cycle was 18 days, varying between 16 and 21 days. During the months from
September to November, the interval between two successive heats was shorter
than from December to February (Amir, 1964; Amir & Volcani, 1965a). In a
study on the length of 252 oestrous cycles of 64 Awassi ewes, Schindler and
Amir (1972) found an average duration of 17 days and ten hours, ranging from
15.5 to 20 days (Fig. 3-11).
At an experiment
station, about 70 percent of recurrent heats had intervals of 14-19 days, the
remaining 30 percent abnormally shorter or longer intervals (Table 3-7).
Excessively long intervals may be a result of silent heats or the death of a
fertilized ovum or embryo.
In an Awassi flock
in Lebanon, the duration of 347 heats ranged from 16 to 59 hours, with an
average of 29 hours. Nine percent of the heats were silent — as manifested by
the occurrence of multiple cycles — accompanied by the absence of a mating
response (Barr, 1968). In a study on the length of 320 oestrous cycles in 65
adult Awassi ewes, Schindler and Amir established an average duration of 35.3
hours, varying between a minimum of 16 hours and a maximum of 84
hours (Fig.
3-12).
The Awassi ewe
displays few outward signs of oestrus. She stands quietly in front of the ram
for mounting. Loss of appetite is marked. The os uteri opens at the onset of the oestrus,
sometimes 4-52 hours earlier or a few hours later. The vulva is slightly
swollen, and the vaginal mucosa, varying between
pale rose and red in colour, is congested until a short time after ovulation.
Two to three days before the beginning of oestrus a thick, creamy white or
yellowish mucous secretion accumulates around the external os of the
slightly dilated cervix, indicating the rise of the oestrogen level. At the
onset of oestrus, or a little before or shortly after, this is usually replaced
by a copious, cloudy or clear secretion. Its presence indicates that the ewe is
still in the first part of the oestrous period. The flow of mucus is strongest
at the height of the heat. The cloudy or transparent secretion generally
disappears after a lapse of about two-thirds of the total oestrous period,
giving way to a white, more viscous discharge which indicates the decline of
oestrogen concentration, the approach of the end of oestrus, and the nearness
of ovulation. Toward the end of the heat the viscous secretion is followed by a
thick creamy or cheesy one, which remains for two or three days after
completion of oestrus (Barr, 1968;
Schindler & Amir, 1972).
Figure 3-11. Average oestrous cycles of 64 Awassi ewes (3-5 cycles per ewe).
(Source: Schindler &Amir, 1972)
|
| |||||||||||||||||||||||||||||||||||||||||||||||||||
Figure 3-12. Average duration of oestrus in 65 Awassi ewes (4-6 cycles per ewe).
(Source: Schindler & Amir, 1972)
n an experimental
Awassi flock in Lebanon, 25 ewes were slaughtered after four successive
oestrous cycles at different phases of the fifth cycle and their reproductive
organs examined. Pro-oestrus was found to be short and rather indefinite and
the onset of oestrus abrupt, while the cessation was gradual. The Graafian
follicles were fully mature and bulged above the ovarian surface, displaying a
tense structure to the touch for 4-29 hours, with an average of 16 hours. There
were 11 ovulations from the right, 12 from the left, and two from both ovaries.
During heat, the uterine horns and musculature were tonic and erect. In the
course of five to eight days after the onset of heat, the corpus luteum developed to maturity,
being conical in shape, about 1 cm in diameter and greyish-red in colour. Its
regression commenced on the thirteenth day after the commencement of oestrus,
taking a gradual course until its termination with the sudden manifestation of
heat (Barr, 1968).
Observations with
a universal peritoneoscope of follicular changes preceding and following
ovulation in adult Awassi ewes, beginning 24 hours after the onset of oestrus
and continuing at intervals of six hours until the rupture of one follicle,
showed that six hours before the final inspection, the follicle had grown
considerably, bulging above the surface of the ovary. In its translucent centre
there was a net of tiny blood vessels. After rupture of the follicle, a small
blood stain and a slight depression were observed in its centre, and sometimes
a small blood clot was prominent above the surface of the ovary. The time range
of ovulation was from 12 hours before to eight hours after the end of oestrus,
with an average occurrence within an hour after the termination of heat. In
Awassi ewes with long oestrous cycles there was a tendency for ovulation to
precede the end of oestrus, while in ewes with shorter heat periods ovulation
usually occurred after the end of oestrus (Schindler & Amir, 1972).
In unimproved
Awassi sheep with pasture feeding throughout the year, the height of the
lambing season is generally one or two months later than in the improved dairy
type. But in a well-fed flock in Lebanon, more than half of 1 000 lambings had
already occurred by January (Table 3-8).
In a stationary
Awassi flock at the American University farm in Lebanon in which the rams were
kept with the ewes throughout the year, the lambing percentages given in Table
3-9 were recorded for the period 1955-63 (Rottensten & Ampy, 1971a). The
same authors compared the lambing performance of Awassi ewes under two
different breeding systems: I - During the period 1955-63, rams were kept with
the ewes throughout the year; and II - In 1964-67 they joined the ewes for
periods of two months each, in October-November, February-March and June-July,
and were separated from them during the other months of the year. Under the
latter system a considerable proportion of the ewes conceived outside the normal
breeding season and 63 percent of the lambings occurred at eight-month
intervals, thus increasing the annual lambing performance. The conception rate
amounted to 85 percent of available ewes in
October-November, 58 percent in February-March, and 43 percent in June-July
(Table 3-10).
| |||||||||||||||||||
| ||||||||||||||||||||||||||||
TABLE 3-13. Distribution of
lambings in improved Awassi sheep in Israel by fortnights | |||||
|
Month |
Date |
Adult
ewes |
Yearlings |
||
|
Number |
% |
Number |
% |
||
|
October |
1-15 |
2 |
0.05 |
|
|
|
|
16-31 |
4 |
0.09 |
|
|
|
November |
1-15 |
8 |
0.18 |
|
|
|
|
16-30 |
139 |
3.17 |
|
|
|
December |
1-15 |
1 047 |
23.89 |
|
|
|
|
16-31 |
1 327 |
30.28 |
|
|
|
January |
1-15 |
714 |
16.29 |
3 |
0.97 |
|
|
16-31 |
431 |
9.84 |
5 |
1.61 |
|
February |
1-15 |
341 |
7.78 |
14 |
4.50 |
|
|
16-28 |
144 |
3.29 |
25 |
8.04 |
|
March |
1-15 |
79 |
1.80 |
40 |
12.86 |
|
|
16-31 |
66 |
1.51 |
48 |
15.43 |
|
April |
1-15 |
28 |
0.64 |
70 |
22.51 |
|
|
16-30 |
33 |
0.75 |
65 |
20.90 |
|
May |
1-15 |
9 |
0.20 |
28 |
9.00 |
|
|
16-31 |
6 |
0.14 |
11 |
3.54 |
|
June |
1-15 |
2 |
0.05 |
2 |
0.64 |
|
|
16-30 |
2 |
0.05 |
|
|
|
Total |
|
4 382 |
100.00 |
311 |
100.00 |
Source: Finci, 1957 | |||||
In Syria, at the
University of Aleppo School of Agriculture, the main
lambing month in an Awassi flock — derived from various desert flocks and
regions — was December, followed by January (Table 3-11).
In Iraq, the main
Awassi lambing season appears to be still earlier than in Lebanon and Syria,
namely in November. At the Abu-Ghraib Experiment Station, Juma and Faraj
recorded the monthly distribution of lambings in five consecutive lambing
seasons given in Table 3-12.
In improved Awassi
flocks in Israel the distribution of lambings, with one lambing a year, ranges
around the peak month of December for adult ewes and April for yearlings (Table
3-13 and Fig. 3-13).
In an Awassi flock
in Lebanon, the average interval between lambing and the following oestrus was
214 days. After the birth of male lambs, the interval was found to be three
days shorter than with female lambs, but the difference was not statistically
significant (Choueiri, Barr &
Khalil, 1966).
In the improved
type of Awassi in Israel, ewes lambing early in the season may come into heat
again toward the end of the year, approximately 40 days after lambing, and on
many farms these are then mated or inseminated. Of the adult ewes of a flock
20-25 percent may thus lamb once more, increasing the total annual milk yield
and number of lambs for each ewe.
Trials to obtain two lambings a year in improved Awassi ewes were conducted by Morag and Eyal (1971) in a flock of 700 Awassi ewes in the northern Negev, and in another one of 450 ewes in the Plain of Esdraelon. The level of feeding and management of the two dairy flocks was similar. The ewes received 0.8 feed unit a day for maintenance and 0.8 feed unit for the production of each kilogramme of milk, including an estimated daily quantity of 900 g of milk consumed by the lambs of one of the two flocks until weaning at 40 days. In the fourth month of pregnancy a supplement of 0.4 feed unit, and during the fifth month 0.6 feed unit, were added to the daily ration.
In the first
trial, 166 ewes — which had lambed at the end of November or
the beginning of December — were separated from their lambs six hours after
parturition and the lambs were reared artificially. Between the twelfth
and eighteenth day after lambing, 71 of the 166 ewes received five
intramuscular injections of 16 mg of progesterone in an oily solution on five
consecutive days and a final injection of 500 IU of PMS on the sixth day. The
remaining 95 ewes did not receive hormone treatment. Rams stayed with the ewes
for 100 days after lambing, except at milking time. The conception rate was
lower in the ewes treated with hormones than in the control group, namely 49
percent as against 59 percent. The interval between previous lambing and
conception was 52 days in the ewes without hormone application and 49 days in
those that were treated. With hormone treatment, the average number of live
births from two consecutive pregnancies in a single year was 2.59, as against
2.34 without hormone treatment.
The second trial
included 83 ewes that had lambed during the first fortnight of September. The
lambs stayed with their dams for suckling during the night until weaning at 40
days. Rams accompanied the ewes for 100 days from the time of lambing.
Seventy-four ewes (or 89 percent) conceived during this time, while nine (or 11
percent) did not become pregnant. The average interval between lambing and
conception was 65 days. The mean number of live births from the two consecutive
pregnancies within one year was 2.78 as against 1.33 lambs from the single
pregnancies of the nine ewes that did not conceive in the 100 days after
lambing (Morag & Eyal, 1971).
Artificial insemination has been
practised in many Awassi flocks in Israel in the past and is still continued in
several of them as a labour-saving device at mating time and as a means of
genetic improvement. It permits the employment of a small number of the best
proven sires and the wide application of progeny-testing. A single ejaculate
can fertilize a large number of ewes independent of location and the time of
ejaculation or oestrus. Finally, the artificial insemination of Awassi ewes is
indispensible in cross-breeding with thin-tailed rams, such as the East
Friesian, which are unaccustomed to lifting the fat tail of the ewe for mating.
The semen,
ejaculated into an artificial vagina, is commonly used in the fresh undiluted
state. Table 3-14 gives the characteristics of semen from five two- to
five-year-old Awassi rams, examined by Schindler, Volcani and Eyal during five
consecutive breeding seasons (June-August) for the purpose of
artificial insemination. Considerable individual differences in semen quality,
concentration and total number of spermatozoa were found by the authors in 11
Awassi rams with at least four ejaculates each (Table 3-15).
A highly
significant correlation exists between the volume of an ejaculate and the
number of spermatozoa it contains ; there is no
correlation, however, between the volume of an ejaculate and the concentration
of spermatozoa. Since the volume occupied by the spermatozoa is relatively
small (l/109 sperm cells occupy 70-80 ml), it may be inferred that a larger volume of an
ejaculate is mainly the result of an additional quantity of secretions from the
accessory glands and only to a small extent is it because of a larger number of
spermatozoa. However, as large ejaculates generally contain more sperm than
less voluminous ones, they are superior for artificial insemination. A larger
number of spermatozoa in an ejaculate is also usually
accompanied by a higher quality of spermatozoa, as indicated by the positive
correlation between the number of spermatozoa in an ejaculate and the
percentage of sperm with progressive motility.
|
| ||||||||||||||||||||||||||||||||||||||||||||
The quality of
Awassi semen decreases with a reduction of the interval between ejaculations
from four or more days to one. For artificial insemination, semen quality also
declines rapidly with repeated ejaculations at intervals of only one or two
days (Fig. 3-14; Table 3-16). A higher percentage of abnormal sperm — tailless,
misshapen or with tapering heads, enlarged middle pieces, or adhered, coiled or
bent tails — appears in the ejaculates. In addition, such increased use of
Awassi rams reduces their libido (Schindler,
Volcani & Eyal, 1957).
The success of
artificial insemination depends to a marked degree on its timing in the hours
of oestrus. Amir and Schindler (1972,
1974), using a single dose of 0.1 cc of fresh undiluted semen with 400 million spermatozoa for each ewe in an Awassi flock,
found that insemination in the first three hours of oestrus gives poor results,
while insemination between four and 40 hours from the beginning of oestrus
results in a considerably higher percentage of pregnancies (Table 3-17).
Figure 3-14. Effect of frequency of ejaculations on semen quality. (Source: Schindler, Volcani & Eyal, 1957)
|
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||
The highest
conception rate was obtained from inseminations performed 16-24 hours after the
onset of oestrus. Earlier or later inseminations gave lower pregnancy rates,
which were statistically significant for the earlier inseminations (Table 3-18)
(Schindler & Amir, 1973).
If the artificial
insemination of Awassi ewes is carried out in the middle of oestrus, it is
possible to inseminate 40-50 animals with a single diluted ejaculate and
achieve 70 percent fertility, but earlier or later inseminations require larger
sperm doses (Amir & Schindler, 1972).
The spermatozoa
enter the folds of the uterine cervix whence they proceed in waves to the
oviduct where their maximal concentration occurs approximately 16 hours after
mating or artificial insemination. With a large dose of spermatozoa, their
number at the place of fertilization suffices at all stages of oestrus to
fertilize the ovum. But if the dose used contains only a limited number of
sperm, the timing of the insemination is important to ensure the presence of a
sufficient number of spermatozoa in the oviduct at the time of ovulation which
occurs at the end of the oestrus. Insemination with a small number of sperm
must be done about 16 hours before ovulation, that is, about the middle of the
oestrous period. Accordingly, it is recommended to inseminate those Awassi ewes
shown by the teaser to be in oestrus in the evening, on the following morning,
and to inseminate those picked out by the teaser in the morning in the evening
of the same day.
The feasibility of
using smaller numbers of spermatozoa — 40, 80 and 120 million — in an
insemination dose was tested by Schindler
and Amir (1973) in a trial with 206 Awassi ewes. The conception rates
obtained from the three sperm doses decreased with decreasing sperm numbers,
but the differences were not statistically significant (Table 3-19).
With one ejaculate
of undiluted semen about ten oestrous ewes can be inseminated. In village
flocks of the Qazvin area of Iran the artificial insemination of ewes with
undiluted semen from improved Awassi rams had the results given in Table 3-20.
To raise
efficiency in the use of ejaculates and increase the number of Awassi ewes that
can be fertilized with a single ejaculate, various diluents have been tested
with varying success (Schindler &
Amir, 1961). In a trial with yolk-citrate-glycine-fructose (YCGF), with or
without catalase, Amir et
| |||||||||||||||||||
| |||||||||||||||||||||||||||||||||||||||||||||||||||||
Storage permits the
use of semen from superior sires for insemination in several flocks at the same
time. But during storage the percentage of motile spermatozoa speedily
decreases. In the reduction of the number of spermatozoa capable of
fertilization, storage resembles the effect of dilution. Hence, a larger number
of spermatozoa must be included in a dose of stored semen than of fresh
undiluted sperm. Awassi semen kept at a temperature of 4°C deteriorates in a
very short time. Amir and Schindler found that the storage of semen diluted
with skimmed milk and containing 150 million sperm in each insemination dose of
0.2 cc for 12 hours at 10°C did not reduce the lambing rate of the ewes, but
storage of the diluted semen for 24 hours lowered the lambing rate (Table
3-22).
| |||||||||||||||||||||||||
Gestation
period. In a flock of unimproved Awassi ewes maintained at
the Terbol Animal Breeding Station in Lebanon, Choueiri, Barr and Khalil (1966)
recorded a mean gestation period of 149.5 days for 336 male lambs and 148.6
days for 370 female lambs, male lambs thus being carried 0.9 days longer than female
lambs. There was some evidence that the length of the gestation period was
influenced by the plane of nutrition during the last two months of pregnancy, a
low plane shortening it and vice versa. In another flock of Awassi sheep,
assembled from six different regions in Lebanon, the gestation length for
single-born lambs was 151.2 days on average (Fox et al., 1971). In a
flock established in Palestine (Merhavia) in 1931, Hirsch (1933) recorded an
average gestation period of 152 days. A similar average length of gestation,
152.6 days, was found by McLeroy and Kurdian (1958) in 44 recorded matings in
an Awassi flock at the American University farm in Lebanon. Lambs born after a
longer gestation period are generally larger than those lambed after a shorter
one.
In an experimental
flock of improved Awassi sheep in Israel, Goot (1966) recorded a mean gestation period of 151.5 days for 48 single male lambs, and 151.4
days for 37 single females. Twins were carried 0.3 days less than singles. In
900 ewes of a highly improved flock (at 'Eyn Harod) the average gestation
period over several years was found to be 152 days, with the distribution as
given in Table 3-23.
Fecundity.
In Lebanon the lambing percentage of mature Awassi breeding ewes usually
averages about 60 (McLeroy & Kurdian, 1958). In Syrian Awassi flocks
fertility is also low, 70-80 lambs for every 100 ewes (Gadzhiev, 1968). Erokhin
(1973) gives a higher figure for the lambing percentage of Awassi sheep in
Syria, namely 105-110.
In a flock of 189
Awassi ewes at the Terbol Animal Breeding Station, a twinning rate of 11.46
percent in 1 006 lambings was recorded during the period 1959-65 (Choueiri, Barr & Khalil, 1966). In an
Awassi flock of Syrian derivation at the American University farm in Lebanon
there were only 4 percent twins among 142 lambs born from 1954/55 to 1957/58
(McLeroy & Kurdian, 1958). Later, Rottensten and Ampy (1971b) reported an
average twinning rate of 24.4 percent in 242 lambings in the same flock in
different seasons of the year.
In Turkey, the
twinning rate of İvesi sheep increased by 'up to 12 percent' (Yalçin, 1979). At Hammām Al'Alil in northern Iraq, the
average lambing percentage of 584 lambings of Awassi ewes in the years 1965-71
was 108.56, ranging from 106.73 to 113.19 in different years (Ghoneim et al, 1973).
In Awassi flocks
of the fellahin and bedouin not more than 5 percent of the adult ewes have
twins. Hirsch (1933) wrote
that 'the Awassi sheep usually lambs one lamb; twins are the exception'. An
investigation of the twinning rate of flock-book ewes in Palestine, made in
1945, showed only 5.52 percent twins in a total of 4 090 births. But in
1953/54, 929 registered ewes from four flocks had a twinning percentage of
10.16 in 3 562 births. In two of these flocks the twinning rate had increased
from 6.08 percent in a total of 987 births in 1942/43 to 9.66 percent in 2 206
births in 1953/54 (Finci, 1957). During the years 1957/58 to 1961/62 Goot
(1966) recorded 10.1 percent twin births in 414 ewes served, and 11.2 percent
twinnings in 375 lambings (90.6 percent) in an experimental flock.
In a flock of 450 high-producing dairy ewes of a communal settlement in the Plain of Esdraelon (1926-61), in a similar flock of improved Awassi sheep at an agricultural school in the south of Israel (1954-61), and in a moderately large experimental flock in the centre of the country (1954-62), Epstein and Herz recorded the birth data given in Table 3-24.
|
TABLE 3-24. Comparison of birth
data of three flocks in Israel |
||||||||||
|
Type of birth |
First
birth of 1-year-old dams |
Second
of 2-year-c |
birth
ilddams |
First
birth of 2-year-old dams |
Subsequent
births |
Total
births |
||||
|
No.
of births |
% of total |
No.
of births |
% of total |
No.
of births |
% of total |
No.
of births |
% of total |
No.
of births |
% of total |
|
|
All births |
141 |
100.0 |
141 |
100.0 |
777 |
100.0 |
3
290 |
100.0 |
4
349 |
100.0 |
|
Single |
134 |
95.0 |
123 |
87.2 |
724 |
93.2 |
2
638 |
80.2 |
3
619 |
83.2 |
|
Twins |
7 |
5.0 |
18 |
12.8 |
52 |
6.7 |
649 |
19.7 |
726 |
16.7 |
|
Triplets |
— |
— |
— |
— |
1 |
0.1 |
3 |
0.1 |
4 |
0.1 |
|
Sex of lamb |
|
|||||||||
|
Both sexes |
148 |
100.0 |
159 |
100.0 |
831 |
100.0 |
3
945 |
100.0 |
5
083 |
100.0 |
|
Male |
79 |
53.4 |
82 |
51.6 |
398 |
47.9 |
1
964 |
49.8 |
2
523 |
49.6 |
|
Female |
69 |
46.6 |
77 |
48.4 |
433 |
52.1 |
1
981 |
50.2 |
2
560 |
50.4 |
|
|
Type of birth |
|
Average
no. of lambs |
|
|
|||||
|
|
First birth of 1 -year-old dams |
|
1.05 |
|
|
|||||
|
|
Second birth of 2-year-old dams |
|
1.13 |
|
|
|||||
|
|
First birth of 2-year-old dams |
|
1.07 |
|
|
|||||
|
|
Subsequent births |
|
1.20 |
|
|
|||||
|
|
Total births |
|
1.17 |
|
|
|||||
Source: Epstein & Herz, 1964 | ||||||||||
Figure 3-15.
Annual fluctuations in twinning percentage in an improved Awassi flock over
30 years. (Source: Epstein &Herz, 1964)
|
TABLE 3-25. Mean twinning
percentages in an improved Awassi flock for three successive periods |
|
|
Period |
Mean
twinning percentage |
|
1929/30-1938/39 |
6.4 |
|
1939/40-1949/50 |
14.4 |
|
1950/51-1960/61 |
17.7 |
Source: Epstein and Herz,
1964 | |
Figure 3-15, which
shows annual fluctuations in the twinning percentage for the period
1929/30-1959/60, is based on data recorded for a large flock of improved Awassi
sheep where selection for high milk yields was practised but not for twinning.
In Table 3-25, the annual twinning percentages are combined into averages for
three successive periods.
During the period
1969-74, the percentages of single, twin, triplet and quadruplet births in four
highly improved Awassi flocks in Israel were as shown in Table 3-26 (for
numbers of lambs see Table 3-37).
In an Awassi flock
of Israeli derivation in Iran, the reproductive performance was recorded for
one-year-old, two-year-old and adult ewes over the course of four years
(1967-70) (Table 3-27).
| |||||||||||||||||||||||||||||||||||||||
Finci (1957) found
that twinning in improved Awassi ewes in Israel was more frequent in the early
part, rather than in the later part, of the lambing season. Examining 3 960
single and 836 twin births in four improved flocks, he reported that 42.5
percent of all twin births had occurred before the middle of December, but of
the single births the figure was only 26.8 percent. The same observation was
made in Iraq (Asker, 1964). Awassi ewes served early in the mating season
produced more lambs than those mated later. At the American University farm in
Lebanon, the twinning rates recorded for the years 1964-67 in a flock of Awassi
ewes that was joined by rams for periods of two months alternating with equal
intervals of separation are given in Table 3-28.
In 24 improved
flocks in Israel investigated by Finci (1957), 1 473 of 5 078 ewes registered
in the flock book had lambed twins once or several times, the average
percentage of ewes with twin births thus
being 29.1. The mean number of lambs for each birth of ewes with one or more
twin births was 1.42. Also, 63.2 percent of the twins of these ewes were lambed
before the end of December. The number and percentage of ewes with one or more
twin births in four improved flocks in Israel were as given in Table 3-29.
| ||||||||||||||||||||||||||||
The influence of
age on twinning has been studied in Lebanon as well as in Israel. In a flock of
Awassi sheep of Syrian derivation in Lebanon, the twinning rate in 368 ewe
years in the period 1955-63 increased gradually from 5 percent at the first
lambing of two-year-old ewes to 30-35 percent at the sixth lambing when the ewes
were about seven years old (Rottensten & Ampy, 1971a). A study of the
effect of the dam's age on twinning in an experimental flock of improved Awassi
sheep in Israel also showed a rise in the twinning rate with increasing age
(Table 3-30).
Records in four
improved Awassi flocks show that, similar to observations in Lebanon, the
percentage of twin births increases only until the age of six (Table 3-31).
Thereafter it drops again, albeit at only a moderate rate (Finci, 1957).
| |||||||||||||||||||||||||||||||||||||||||||||
A further examination of 1 375 ewes
with twin births from 24 improved Awassi flocks also showed an increase in the
twinning rate until the age of six and a decrease thereafter (Table 3-32).
Sex ratio.
In 4 973 Awassi lambs born in four improved flocks in Palestine in 1942/43
and in Israel in 1953/54, Finci (1957) registered 50.4 percent males and 49.6
percent females. In another survey of 083 lambs, including singles, twins and
triplets, the ratio of males to females was 49.6:50.4 (Epstein Herz, 1964). In
an experimental flock of improved Awassi sheep there were 56.7 percent male and
43.3 percent female lambs in 210 births (Goot, 1966).
In 3 619 single
lambs of an improved flock in Israel, the sex ratio was 50.1:49.9. There were
710 lambs in mixed male and female twin births against 346 males and 396
females in those of equal sex. In the latter, the ratio was therefore
46.6:53.4, and in the total of 1 452 twins, 48.3:51.7. In four highly improved
dairy flocks, the sex ratio of 6 960 single lambs born in the period 1969-74
was 52.5:47.5, and
| ||||||||||||||||||||||||||||||||||||||||||
in 2 846 twin lambs, 48.1:51.9. The ratio of male to female
to mixed twin births was 100:118:246. The number of triplets and quadruplets
was too small to provide a statistically significant sex ratio. In a flock of
improved Awassi sheep of Israeli derivation in Iran, the sex ratio in 279
single lambs was 51.6:48.4, and in 86 twins, 41.9:58.1 (Wallach & Eyal,
1974).
Among 1 006 lambs of an Awassi flock in Lebanon, Choueiri, Barr and
Khalil (1966) recorded a ratio of 48.3 males to 51.7 females. But in a
stationary Awassi flock purchased from Syrian nomads for the American
University farm in Lebanon, the number of males exceeded that of females; in 246
single lambs it was 52.4:47.6 and in 122 twins, 57.4:42.6 (Rottensten &
Ampy, 1971a).
In Anatolian İvesi (Awassi) sheep, Yarkin and Elitjin (1966) found an
overall sex ratio of 49.3 male to 50.7 female single and twin lambs; 22.8
percent of the twin pairs were male, 24.6 percent female, and 52.6 percent of
both sexes.
The data recorded in Anatolia and in Israel convey the impression that
with regard to twin births of equal sex, males have a smaller chance of being
born (or being born alive) than the female Awassi twins.
In an Awassi flock at Hammām AP Alii Experiment Station in northern
Iraq, the sex ratio of 634 male and female lambs born in the years 1965-71 was
52.2:47.8. The difference between single and twin lambs was as shown in Table
3-33.
Barrenness. In an Awassi flock in Lebanon
comprising 60 yearling and 15 older ewes that was accompanied by four rams from
June 1965 to January 1966, 4 percent of the ewes were barren (Husnaoui&Fox,
1967). In another flock, obtained from six different regions in Lebanon, 10
percent of the 391 ewes that came into heat did not lamb, ranging from 2 to 26
percent among regional groups (Fox et al., 1971). In a stationary Awassi
flock of Syrian derivation at the American University farm in Lebanon where the
rams were kept with the ewes throughout the year, 14 percent of the ewes did
not conceive in the years 1955-63 on an annual average. In a trial in the same
flock in which the rams alternately joined the ewes for two months and were
separated from them during the following two months, 139 of 381 ewes (or 36.1
percent) did not become pregnant during the annual period of six months in
which mating was possible (June-July, February-March, October-November)
(Rottensten & Ampy, 1971b).
In an İvesi (Awassi) flock at the Ereğli Animal
Breeding Research Station in central Anatolia, 20 percent of the ewes mated in
1966/67 and 12 percent of those mated in 1968/69 remained barren (Yalçin &
Aktaş, 1969).
In Egypt, 20 percent of a group of Awassi ewes used as untreated control
sheep in a trial with three other groups of ewes treated with progesterone and
PMS did not conceive (El-Mekkawi, 1965).
In two improved Awassi dairy flocks examined in 1942/43 in Palestine and
1953/54 in Israel, Finci (1957) recorded 1.12 percent barren ewes and 0.42
percent abortions. However, the computer records of all milk-recorded Awassi
ewes in Israel for the years 1972/73 and 1973/74 show considerably higher
percentages of barren ewes (see Table 3-34).
Still birth and lamb mortality.
In Awassi flocks of the bedouin and fellahin, the mortality rate is 15-20
percent in normal years and up to 50 percent in years of drought or severe
winters (Hirsch, 1933).
While this refers to flocks as a
whole, the mortality of lambs is certainly not less than that of adult sheep.
Indeed, in Syrian Awassi flocks belonging to bedouin, the mortality of lambs
shortly after birth reaches 5-10 percent in favourable years and 30-50 percent
in years with cold winters and snow-covered pastures when the ewes starve. In
fellahin flocks, kept in villages where the ewes lamb in protected places and
are given some straw in addition to pasture, lamb mortality is less than in
bedouin flocks (Hirsch, 1932).
In Iraq, famine and disease are
reckoned to reduce the average lamb crop to 40-60 percent (Williamson, 1949).
At the Hammām Al' Alii farm of the University of Mosul where the nutrition and
management of sheep are superior to those commonly found in bedouin and
fellahin flocks, Ghoneim etal. (1973) recorded the mortality
rates of single and twin Awassi lambs from birth to weaning during the six-year
period 1965/66-1970/71 (Table 3-35).
| |||||||||||||||||||||||||
Among the 4 973
new-born lambs of two Awassi flocks studied in 1942/43 in Palestine and 1953/54
in Israel, 2.05 percent were stillborn or died during the first week of life
(Finci, 1957). In an experimental flock in Israel, the mortality rate of 210
lambs from birth to six months was 9.5 percent, 5.5 percent for single and 18.5
percent for twin lambs (Goot, 1966). The mortality rates of single and twin
male lambs in this flock exceeded those of female lambs until the age of 180
days, as shown in Table 3-36.
During the years
1969-74, mortality in the first week of life of single, twin, triplet and
quadruplet lambs born in four improved dairy flocks in Israel was as shown in
Table 3-37. From these data it would appear that in male Awassi lambs the rate
of mortality during the first week of life is about twice as high as in female
lambs.
The computer
records of all milk-recorded Awassi flocks in Israel furnish the data given in
Table 3-38 on the still births and mortality of lambs in the first week of life
in 1972/73 and 1973/74, excluding lambs from second lambings in a single year.
In a trial to
introduce summer lambing in Awassi dairy flocks in addition to lambing during
the normal winter lambing season, Alef recorded the mortality losses for
summer-born lambs (Table 3-39).
Through the
introduction of improved methods of hygiene, management and feeding in
subsequent seasons, the high mortality rate in summer-born lambs was reduced to
normal proportions, similar to those obtaining in the winter lambing season
(Alef, 1972).
According to the
computer records of milk-recorded Awassi flocks in Israel for the years 1972/73
and 1973/74, the still births and first-week mortality of lambs from second
lambings in a year were as given in Table 3-40.
In countries where
the Awassi is not indigenous but has been imported in relatively small numbers,
the mortality rate of lambs during the period of acclimatization in a new
microbial environment is usually high.
In a flock of Awassi
sheep of Israeli derivation stationed in Athalassa in Cyprus, lamb mortality
during the suckling period was recorded for the years 1969-71 and 1971/72
(Table 3-41). In Iran, Wallach and Eyal recorded the lamb mortality percentages
for different years in an improved Awassi dairy flock imported from Israel
(Table 3-42). The mortality rate of male lambs was considerably higher than
that of females, a phenomenon that has also been observed in improved Awassi
dairy flocks in Israel (see Table 3-43).
| |||||||||||||||||
TABLE 3-37. Mortality of lambs in 1 st week of life in four improved Awassi flocks, 1969-74 | ||||||||
|
Flock
no. |
No.
of live births |
|||||||
|
Total |
Single |
Twins |
Triplets |
Quadruplets |
||||
|
♂ |
♀ |
♂♂ |
♀♀ |
♂♀ |
||||
|
1 |
4 161 |
1 396 |
1 214 |
306 |
332 |
904 |
9 |
0 |
|
2 |
2 227 |
849 |
794 |
140 |
158 |
276 |
6 |
4 |
|
3 |
1 997 |
778 |
772 |
114 |
126 |
192 |
15 |
0 |
|
4 |
1 458 |
630 |
527 |
54 |
106 |
138 |
3 |
0 |
|
Total |
9 843 |
2 653 |
3 307 |
614 |
722 |
1 510 |
33 |
4 |
|
Mortality
in 1st week of life (%) |
||||||||
|
Flock
no. |
Single |
Twins |
Triplets |
Quadruplets |
||||
|
♂ |
♀ |
♂♂ |
♀♀ |
♀♂ |
||||
|
1 |
6.38 |
2.47 |
0 |
0.30 |
7.74 |
0 |
0 |
|
|
2 |
9.54 |
4.53 |
8.57 |
1.90 |
7.25 |
0 |
50 |
|
|
3 |
6.17 |
6.22 |
12.28 |
7.94 |
8.33 |
33.33 |
0 |
|
|
4 |
4.29 |
0.76 |
1.85 |
0 |
0.72 |
0 |
0 |
|
|
Average |
6.71 |
3.57 |
4.40 |
1.94 |
7.09 |
15.15 |
50 |
|
TABLE 3-38. Mortality of lambs in Awassi flock in Israel in 1st week of life |
Year |
Age of ewes |
No.
of ewes |
Lambs
per birth |
Of
these: stillborn |
Mortality
during 1stweek(%) |
|
1972/73 |
Yearling |
3 257 |
1.1 |
0.1 |
5.6 |
|
2-year-old |
2 838 |
1.1 |
0.1 |
4.3 |
|
|
Adult |
6 485 |
1.2 |
0.1 |
4.3 |
|
|
|
Total |
12
580 |
1.15 |
0.1 |
4.6 |
|
1973/74 |
Yearling |
2 256 |
1.1 |
0.1 |
8.9 |
|
2-year-old |
2112 |
1.1 |
0.1 |
5.6 |
|
|
Adult |
4 937 |
1.2 |
0.1 |
5.5 |
|
|
|
Total |
9 305 |
1.15 |
0.1 |
6.3 |
In Spain, the data
in Table 3-44 on the mortality of lambs in a flock of improved Awassi dairy
sheep originating in Israel were recorded for the years 1972/73 and 1973/74.
In 1972/73, 5.4
percent of the mortalities occurred during the first week and 0.5 percent
during the second month. In 1973/74, 1.3 percent of the lambs born alive died
during the first week, 3.0 percent during the second month, and 5.4 percent
later. In the same year, the still births and mortality
TABLE 3-40. Mortality of lambs
born at second lambing in a year |
Year |
Age of ewes |
No.
of ewes |
|
Lambs
per birth |
Of
these: stillborn |
Mortality
during 1stweek(%) |
|
1972/73 |
Yearling |
3 |
|
1.2 |
— |
— |
|
2-year-old |
132 |
|
1.2 |
0.1 |
6.5 |
|
|
Adult |
679 |
|
1.2 |
0.1 |
5.6 |
|
|
|
Total |
814 |
Average |
1.2 |
0.1 |
5.7 |
|
1973/74 |
Yearling |
2 |
|
1.0 |
— |
— |
|
2-year-old |
82 |
|
1.1 |
— |
3.7 |
|
|
Adult |
391 |
|
1.2 |
— |
4.0 |
|
|
|
Total |
475 |
Average |
1.18 |
— |
3.9 |
| |||||||||||||||
| |||||||||||||||||||||||||||||
of lambs
from yearling ewes was 18.8 percent, from two-year-olds 11.3 percent, and from
three-year-old ewes 10.5 percent. The most frequent causes of death from
disease were congestion of the lungs, diarrhoea and enterotoxaemia.
Numerous birth weights of lambs
have been recorded in the various countries of the breeding area of the Awassi.
Birth weights are affected by several factors. Foremost among these are sex and
type of birth, single or multiple. As in other breeds of sheep, the level of
nutrition during the last weeks before parturition also influences the birth
weight of Awassi lambs, more especially those of twins. The particular year and
month of lambing, mainly dependent on variable conditions of climate and
pasture growth, affect the birth weights of lambs in flocks that subsist mainly
or entirely on grazing. While the weight of the dam has a significant influence
on the birth weight of her offspring, her age seems to affect the birth weight
of the lamb significantly only for the first lambing.
Unimproved Awassi
lambs weigh 3-6 kg, with an average of 4 kg; 'first-crop lambs are usually
lighter, weighing 3-4 kg' (Hirsch, 1933). In 1929/30 the same author recorded
an average birth weight of 4.63 kg
in 13 male lambs and 4.28 kg in nine females in an Awassi flock belonging to a
communal settlement in Palestine.
In a flock of
unimproved but well-fed Awassi sheep in Lebanon, the mean birth weight of 486
male lambs was 4.29 kg and of 520 female lambs 4.15 kg (Choueiri, Barr &
Khalil, 1966). In a flock of 391 Awassi yearling ewes collected from six
different regions in Lebanon, single male lambs weighed 4.52 kg at birth and
single female lambs 4.05 kg on average (Fox et al., 1971). Also in
Lebanon, Rottensten and Ampy (1971a) found that in a flock of unselected Awassi
sheep originally purchased from Syrian nomads, single lambs were about 21
percent heavier than twins and male lambs 7-9 percent heavier than female
lambs. At the first lambing of two-year-old ewes, birth weights were
approximately 15 percent lower than for later lambings (Table 3-45).
Seasonal differences
in average birth weights were observed by Ampy and Rottensten (1968) in an
Awassi mutton flock at the American University farm in Lebanon in 1965 and 1966
(Table 3-46). However, these were not significant, being attributable mainly to
seasonal differences in twinning rates: 24.5 percent in spring, 9.5 percent in
summer, and 7.1 percent in autumn. There were, however, significant differences
in birth weights in different years (Table 3-47).
In Syria at the
University of Aleppo School of Agriculture, Husnaoui and Fox (1967) recorded
average birth weights of 4.4 (±0.053) kg for male Awassi lambs and 4.0 (±0.049)
kg for females, including 5 percent twins, in a flock of 60 yearling and 15
older ewes acquired from bedouin in various parts of the Syrian desert. Table
3-48 gives the average birth weights of İvesi (Awassi) lambs in Turkey.
| ||||||||||||||||
|
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
In Iraq 40 single,
male Awassi lambs used in a docking trial had an average birth weight of 4.73
kg (Asker, El-Khalsy & Juma, 1964). In a study of the birth weights,
weaning weights and milk production of Awassi sheep, 11 male and eight female
single lambs averaged 4.60 (±0.25) kg and 4.31 (±0.14) kg, respectively, at
birth (Eliya & Juma, 1970b). At Hammām Al'Alil Agricultural
Experiment Station, the average birth weight of male Awassi lambs over three
years was 4.56 kg and of female lambs 4.32 kg, males exceeding females by 240 g in weight. Single lambs were 620 g heavier at birth than twins
(Kazzal, 1973). The birth weights of male and female, single and twin Awassi
lambs were recorded by different authors in Iraq: (I) 2 096 lambs born at the
Abu-Ghraib Experiment Station during the period 1959-62 (Asker, 1964); (II) 923
single and 88 twin lambs born at the same station during five lambing seasons,
1960-64 (Juma & Faraj, 1966) (III) 14 male and 19 female single lambs, and
12 male and 11 female twin lambs used in a study on the effect of sex and type
of birth on weight gains from birth to 48 weeks of age
(Juma et al., 1969); (IV) 12 male and 10 female single lambs, and 10
male and 7 female twins used in a test of their dams' milk yields at Abu-Ghraib
(Karam et al., 1971) (see Table 3-49).
Considerable
annual variations in average birth weights were observed at the Hammām Al'Alii
Agricultural Experiment Station for five consecutive years (Table 3-50).
At
the same experiment station, the birth weights of Awassi lambs born in
December, January and February were higher than those of lambs born in November
and March, that is, the beginning and end of the lambing season. The age of
dams had no significant effect on birth weights (Kazzal, 1973).
In a study on the
effects of different factors on the birth weights of Awassi lambs in Iraq, Juma
and Faraj (1966) suggested that the highly significant monthly and annual
variations encountered might be a result of changes in environmental
conditions, and more especially in feeding conditions. First-lambing
two-year-old ewes had lighter lambs than ewes lambing for the second, third,
fourth or fifth time. When dams were grouped into eight weight classes, a
significant difference in birth weights of lambs was found among classes, dams
weighing 57.2-61.2 kg giving birth to the heaviest lambs (Table 3-51).
| |||||||||||||||||||||||||||||||||||||||||||||
TABLE 3-50. Annual differences
in average birth weights of Awassi lambs in Iraq | ||||||||
|
Year |
Single |
Twin |
||||||
|
|
Male |
Female |
|
Male |
|
Female |
||
|
No. |
Wgt(kg) |
No. |
Wgt(kg) |
No. |
Wgt(kg) |
No. |
Wgt(kg) |
|
|
1966/67 |
25 |
5.30 |
39 |
5.13 |
8 |
3.66 |
4 |
4.25 |
|
1967/68 |
54 |
5.23 |
43 |
5.34 |
9 |
5.41 |
3 |
4.77 |
|
1968/69 |
34 |
4.98 |
41 |
4.51 |
14 |
3.76 |
10 |
4.22 |
|
1969/70 |
56 |
4.83 |
40 |
4.66 |
6 |
3.83 |
10 |
3.57 |
|
1970/71 |
46 |
4.36 |
42 |
4.30 |
5 |
4.10 |
5 |
3.40 |
|
Total/Average |
215 |
4.91 |
205 |
4.79 |
42 |
4.15 |
32 |
3.94 |
Source: Ghoneim et al.,
1973 | ||||||||
In Egypt 140 male
and female Awassi lambs of Syrian descent born during the period 1961-65 had an
average birth weight of 3.78 kg (Fahmy et al., 1968). In a study
of the effect on birth weights of different planes of nutrition for improved
Awassi ewes in Cyprus in the six weeks prior to lambing, 27 single lambs from
ewes kept on a medium plane (straw and 500 g of concentrates a day) weighed 4.9
kg on average, and 25 single lambs from ewes on a high plane (straw and 1 kg of
concentrates) weighed 5.3 kg at birth (Cyprus ARI, 1973). The differences in
mean birth weight between male and female improved Awassi lambs, recorded in
Cyprus in 1969/70, were as given in Table 3-52.
| |||||||||||||||||||||||||||||||||||||||||
| ||||||||||||||||
|
TABLE 3-57. Mean birth weights of
single lambs from first lambings of 2-year-old ewes and average milk yields
in an improved Awassi flock in two 11-year periods |
|||
|
Birth weights of lambs |
Male |
Female |
Average
milk yield per ewe per lactation (I) |
|
1939/40-1949/50 |
|||
|
No. of lambs |
82 |
86 |
|
|
Meanwgt(kg) |
4.5 |
4.2 |
199.5 |
|
SD± |
0.57 |
0.73 |
|
|
1950/51-1960/61 |
|||
|
No. of lambs |
234 |
217 |
|
|
Meanwgt(kg) |
4.9 |
4.6 |
337.9 |
|
SD± |
0.74 |
0.68 |
|
In Israel the
birth weights of Awassi lambs are recorded for the majority of milk-recorded
flocks. Along with the increase in milk yields and, at the same rate, in adult
body size and weight as well as the high plane of nutrition of the ewes,
new-born improved Awassi lambs are now heavier than they have been in previous
years and are considerably heavier than in the unimproved Awassi.
Finci (1957)
reported the birth weights of 4 316 single and twin lambs, adding that in 83.9
percent of the single male lambs recorded, the birth weights varied between 4.0
and 5.5 kg, in 88.2 percent of the single female lambs between 3.5 and 5.0 kg,
and in 82.9 percent of the male and 83.9 percent of the female twins between
3.0 and 4.5 kg. But in an experimental flock Goot (1966) registered
considerably higher mean birth weights for 239 lambs (see Table 3-53).
In connection with
a suckling test with 33 single male and 37 single female lambs from mature
improved Awassi ewes in the period 1952-53, Doron (1954a) established mean
birth weights of 5.22 kg for the males and 4.92 kg for the females.
In two Awassi
mutton flocks in which the ewes were not milked, the birth weights of male and
female single lambs were as shown in Table 3-54.
|
TABLE 3-55. Birth weights of
single, twin and triplet Awassi lambs from 1-year-old, 2-year-old and adult
ewes | |||||||||||
|
Type of birth |
1st
birth of 1-year-old dams |
2nd
birth of 2-year-old dams |
1st
birth of 2-year-old dams |
||||||||
|
No.
of ambs |
Mean
wt(kg) |
SD± |
No.
of lambs |
Mean
wt(kg) |
SD ± |
No.
of lambs |
Mean
wt(kg) |
SD± |
|||
|
Single: |
male |
74 |
4.29 |
0.52 |
61 |
4.78 |
0.73 |
356 |
4.78 |
0.69 |
|
|
|
female |
60 |
4.18 |
0.56 |
62 |
4.57 |
0.56 |
368 |
4.49 |
0.71 |
|
|
Twins: |
♂♀ |
male |
— |
— |
— |
12 |
3.67 |
0.92 |
18 |
3.61 |
0.45 |
|
|
♀♀ |
female |
4 |
3.38 |
0.47 |
6 |
3.33 |
0.53 |
44 |
3.86 |
0.45 |
|
|
♂♀ |
male |
5 |
3.60 |
0.41 |
9 |
3.94 |
0.32 |
21 |
4.03 |
0.63 |
|
|
female |
5 |
3.20 |
0.56 |
9 |
3.81 |
0.37 |
21 |
3.87 |
0.62 |
|
|
Triplets: |
male |
— |
— |
— |
— |
— |
— |
3 |
2.00 |
0.00 |
|
|
|
female |
— |
— |
— |
— |
— |
— |
— |
— |
— |
|
(cont.) | |||||||||
|
|
Type of birth |
Subsequent
births |
Total
births |
||||||
|
No.
of lambs |
Mean
wt (kg) |
SD± |
No.
Of lambs |
Mean
wt (kg) |
SD± |
||||
|
Single: |
|
male |
1
322 |
5.00 |
0.73 |
1
813 |
4.92 |
0.72 |
|
|
|
|
female |
1
316 |
4.71 |
0.62 |
1
806 |
4.64 |
0.65 |
|
|
Twins: |
♂♂ |
male |
316 |
4.19 |
0.56 |
346 |
4.14 |
0.59 |
|
|
|
♀♀ |
female |
342 |
4.00 |
0.56 |
396 |
3.97 |
0.56 |
|
|
|
♂♀ |
male |
320 |
4.17 |
0.73 |
355 |
4.15 |
0.72 |
|
|
|
|
female |
320 |
3.94 |
0.71 |
355 |
3.92 |
0.73 |
|
|
Triplets: |
|
male |
6 |
3.70 |
0.52 |
9 |
3.13 |
0.94 |
|
|
|
|
female |
3 |
3.70 |
— |
3 |
3.70 |
— |
|
|
Source: Epstein & Herz,
1964 |
|||||||||
Figure 3-16. Mean birth weights of single lambs of first-lambing 2 year-old ewes and average milk yields in an improved Awassi flock, 1939/40-1960/61
Epstein and Herz recorded the birth
weights of male and female single, twin and triplet lambs from one-year-old,
two-year-old and adult ewes of an improved Awassi dairy flock (Table 3-55). The
birth weight varied with the dam's age and age at first lambing. The mean
weight differences of single and twin lambs are given in Table 3-56.
Figure 3-16 illustrates how an
increase in mean milk yields, following selection and improved feeding and
management over 20 years, was accompanied by an increase in birth weights. At
the same time the figure shows annual fluctuations in birth weights and milk
yields.
In two successive 11-year periods
when the mean milk yield of an improved Awassi flock for which data were
recorded increased from 199.5 to 337.9 kg, the mean birth weights of single
male and female lambs from the first lambings of two-year-old ewes rose by 400
g (Table 3-57).
In bedouin and fellahin flocks Awassi lambs are usually
suckled for two or three months, depending on the conditions of pasture, the
time of birth, and growth of the lamb. In times of drought, new-born lambs are
considerably smaller and lighter than lambs carried at a time of sufficient
pasture growth. Such small lambs are left with their dams and suckled until
they are capable of subsisting on natural pasture. The suckling period of lambs
born early in the season commonly lasts longer than that of later-born lambs,
not only because early-born lambs are carried during the subtropical, rainless
season when the ewes lose weight owing to a lack of nourishment, but also because
milking is not usually started before a sufficiently large number of ewes are
ready in February and March (Hirsch, 1933). During the suckling period the lamb
is allowed all the milk of the ewe. The dams of male lambs selected for
breeding are not milked until they go dry naturally; this often also holds for
those few ewes with twins.
In Awassi mutton flocks in which
the ewes are not milked, the male lambs nurse until they reach slaughter weight
and the female lambs, required for the replacement of
culled ewes, until their dams dry up.
In improved dairy flocks, the
new-born lamb remains with its dam during the first week of its life day and
night in a small, separate enclosure in the sheep shed. During this time mother
and young get used to each other and the suckling lamb gains strength and
resistance from the colostrum. Twins and triplets too weak to find the teats,
or single lambs whose dams have very large pendulous udders with large teats,
are assisted during the first days until they are capable of sucking without
help. This is done by moving the lamb close to the udder, opening its mouth and
putting the teat into it. If the lamb still refuses to suck, it is placed below
the udder and a little milk is milked into the anterior part of its mouth to acquaint
it with the taste. The teat is then again put into its mouth, when the lamb
will usually begin to suck.
Until the early 1950s, when the
milk yields of Awassi ewes in Israel were still relatively low, the ewes stayed
with their lambs at night for six weeks. In the morning they were milked before
going to pasture and in the evening they again joined their lambs. During the
seventh and eighth weeks the ewes were also milked on their return from pasture
and the lambs received the residual milk in the udder and the milk produced
during the night. Weaning took place at the end of the eighth week when the
male lambs, weighing 15-20 kg, were sold to the butcher and the female lambs
separated from their dams. Male lambs retained for breeding obtained all the milk
of their dams for one or two months more.
The first change in the suckling
regime was slight and continued for only a short period. It occurred in the
second month when restriction of suckling to the night milk began not later
than six weeks and at least after four weeks.
In the second change full suckling
became restricted to the first fortnight. During the next six weeks the lamb
obtained only residual evening milk and the milk produced during the night.
However, it was not weaned after 56 days, as had been the common practice
hitherto, but during the third month it was allowed one residue suckling of
short duration after the evening milking. This measure eliminated the negative
effects of the stress of sudden milk withdrawal after the eighth week on the
growth of the lamb and of separation on maternal instinct by the ewe and the
persistence of her milk yield.
The third change
restricted full suckling to the first week. This was followed by two to three
weeks of suckling after evening milking and throughout the night, eight-hour
suckling after evening milking until the lamb was eight weeks old, and one
short residue suckling after the evening milking during the third month.
At the fourth change full suckling
was again limited to the first week, and in some flocks to only five days.
Thereafter the lamb was not suckled during the night, but was admitted to two
residue sucklings, for three hours after the morning milking and two hours
after the evening milking, until the age of five or six weeks. From then until
the age of 12 weeks it was allowed a one-hour residue sucking after the evening
milking and none in the morning.
The changes were introduced over
the course of approximately ten years, beginning in the early 1950s. Some
flocks passed through every stage, in others one or another stage was omitted,
while again in others the various suckling regimes underwent minor
modifications.
The general practice in improved
Awassi dairy flocks is now one week's full suckling, followed by three or four
nights of suckling, then by two residue sucklings a
day of two hours each until the lamb is six weeks old. During the following
fortnight, until the lamb is eight weeks old, the two daily residue sucklings
are reduced to 30 minutes each. During the third month, the lamb is allowed one
residue suckling of 30 minutes to one hour a day.
At all stages and under all regimes
of restricted suckling, the lambs are not pastured but are kept in the shed
with free access to a balanced concentrate mixture, good hay and drinking water.
The following alternative suckling
regimes for improved Awassi dairy lambs of both sexes have been recommended by
Loew, Dori and Kali (1972):
I. Suckling
of colostrum or, if the lamb is disowned and cannot be put to another ewe in
the colostral stage of milk production, 11 of colostrum — kept in a
refrigerator for emergency use — in four equal portions a day. Until the age of four to six days, unrestricted suckling; twice a
day milking of milk not consumed by lamb. From the age of four to six
days to a weight of 8-12 kg, 10- to 12-hour night suckling; ewe milked in the
evening and morning, that is, before and after suckling time. From the age of
one week, free access of lamb to crushed or ground barley or a concentrate
mixture containing 11.5 percent digestible protein. From the age of 10-14 days
(8-12 kg weight), two residue sucklings of two hours each after milking. Gradual reduction of residue suckling to half an hour. Weaning at 100-120 days at a weight of 30-35 kg in female lambs and
35-40 kg in male lambs. For lambs from winter lambings, a weaning age of
four months is recommended, and from later lambings three months. If ewes are
mated again shortly after lambing, their lambs should be weaned at 60 days when
weighing 18-20 kg.
II. For
the first six days of life the lamb stays with its dam. From the age of seven
days to a weight of 14 kg, it is allowed two residue sucklings of four hours
each a day; from a weight of 20 kg on, two residue sucklings of three hours
each; from 30 kg two residue sucklings of two hours each; from 35 kg, two
residue sucklings of one hour each. Weaning is at 40 kg. Again, lambs born
early in the lambing season should be weaned at the age of four months and
those born late in the season at three months. Throughout the suckling period
the lambs should have free access to crushed or ground barley or a concentrate
mixture.
In the highly improved ram-breeding
Awassi stud flock of Israel the lambs remain with their dams in the lambing box
for one to three days, during which time the ewes are milked twice a day since
at this early age single lambs are incapable of using all the milk produced by
the ewe. From the lambing box the dams and their offspring are transferred to
the flock pen where they stay together for one week during which the ewes do
not go out to pasture. Thereafter the ewes are milked in the evening on their
return from grazing and the lambs are admitted to them for the night. After
three to four weeks, when the lambs have reached a weight of 11-12 kg, night
suckling is replaced by two residue sucklings of a total of eight hours a day
and later by one, of ever lesser duration, until the age of 3 ½ to
four months when the lambs are weaned. Up to the time of weaning the lambs have
free access to hay and concentrates. At weaning, female lambs weigh
approximately 40 kg and males 45-50 kg.
Although in conditions of prolonged drought and a
submaintenance pasture diet young livestock may still increase in size because
their bones continue to grow for a time even though their body weight
decreases, the commonest measure of growth in farm animals is the increase in
live weight (Pomeroy, 1955). In Awassi lambs the growth rate or weight gain
depends on sex, single or multiple birth, suckling
regime, plane of nutrition, and whether or not the fat tail has been docked.
In an experimental
flock at the American University farm in Lebanon, McLeroy and Kurdian recorded
the weights of female Awassi sheep at different ages in the years
1954/55-1957/58 (Table 3-58).
In the same flock, average weaning
weights at 60 days of a total of 91 male and 82 female single Awassi lambs, and
of 64 male and 40 female twins in the years 1963,1965 and 1966 were 15.2,16.8
and 16.6 kg, respectively, and the average daily weight gains from birth to
weaning 188, 215 and 205 g (Ampy & Rottensten, 1968).
Table 3-59 gives the growth rates
from birth to 5½ months of a well-grown male Awassi lamb in Israel
and Table 3-60 of three others that were used in a feeding trial from 122 to
338 days of age.
In another test,
Atzmon and Doron (1951) examined the growth of two groups of male Awassi lambs,
one on a high-level feeding ration until the age of 16 weeks, and the other on
a medium-level ration until 30 weeks. The former, consisting of 18 lambs, most
of which were born in December, obtained all the milk of their dams for three
weeks, half of the milk until the age of 60 days, and one-quarter (one unmilked
half of the udder for 12 hours) during the third month, at the end of which
they were weaned. During the second month of their lives the lambs consumed on
average 200 g of crushed barley and mixed concentrates and 150-200 g of hay;
during the third month, 400 g of barley and concentrates, 500 g of hay and 2.4
kg of green clover; and during the fourth month, 600 g of barley and
concentrates, 400 g of hay and 4.5 kg of clover a day. In the course of the
test the mean weights of the lambs were recorded (Table 3-61).
| |||||||||||||||||||||||||||||
Owing to differences in birth
weight of the lambs, their dams' milk production and their individual capacity
for growth, their weights at the age of one week ranged from 4.5 to 9.0 kg, at
eight weeks from 15.5 to 27.1 kg, and at 16 weeks from 28.5 to 41.0 kg.
The second group, which consisted
of 20 lambs, received the same feeding until the age of eight weeks as did the
first group. In addition, the lambs were given 250 g of concentrates and an ad
libitum quantity of green clover and hay. Consequently, the weight gains of
the lambs of both groups were similar until eight weeks, namely 22.38 and 22.54
kg. Thereafter the lambs of the second group were maintained on a lower level
of feeding. They were not weaned at 90 days but at 60 days and they were sent
out to pasture, receiving an additional concentrate ration of 250 g a day and
an unlimited quantity of clover and hay. The mean weights of the lambs recorded
in the course of this test are given in Table 3-62.
In both tests the
average weekly weight gain during the first eight weeks was approximately 2.5
kg. But weaning at 60 days caused a sharp reduction in weight gains in the
following three weeks (1 060, 350 and 1 000 g, respectively). Only from the
fourth week after weaning did the lambs overcome the setback to some extent;
from then until the sixteenth week of their lives the weekly
|
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
TABLE 3-65. Number of feed units
supplied to three groups of male Awassi lambs |
Mean live weight (kg) |
Feed units per head
per day |
|
|
I |
II |
III |
|
|
30 |
1.00 |
1.20 |
Free access to a
concentrate mixture |
|
35 |
1.05 |
1.25 |
|
|
40 |
1.10 |
1.30 |
|
|
45 |
1.20 |
1.45 |
|
|
50 |
1.30 |
1.55 |
|
|
55 |
1.35 |
1.60 |
|
|
60 |
1.40 |
1.65 |
|
|
65 |
1.45 |
1.75 |
|
|
70 |
1.55 |
1.85 |
|
|
75 |
1.60 |
1.90 |
|
|
80 |
1.65 |
1.95 |
|
Source: Folman, Eyal &
Benjamin, 1967 | |||
|
TABLE 3-66.
Growth rate, feed requirements and feed utilization of male Awassi lambs between the ages of 5 and 10 months |
||||||||||||
|
Period of trial
(weeks) |
Live weight |
Mean daily weight
gain(g) |
Daily feed intake
(feed units) |
Ratio of feed units to
weight gain |
||||||||
|
I |
II |
III |
I |
II |
III |
I |
II |
III |
I |
II |
III |
|
|
0 |
34.5 |
35.1 |
35.0 |
|
|
|
|
|
|
|
|
|
|
1-4 |
39.0 |
42.1 |
42.9 |
161 |
250 |
282 |
1.09 |
1.29 |
1.57 |
6.8 |
5.2 |
5.6 |
|
5-8 |
42.8 |
47.4 |
48.5 |
181 |
252 |
267 |
1.12 |
1.44 |
1.64 |
6.2 |
5.7 |
6.1 |
|
9-12 |
48.2 |
52.8 |
55.4 |
257 |
257 |
329 |
1.18 |
1.52 |
1.74 |
4.6 |
5.9 |
5.3 |
|
13-16 |
51.8 |
57.9 |
60.5 |
171 |
243 |
243 |
1.25 |
1.58 |
1.75 |
7.3 |
6.5 |
7.2 |
|
17-20 |
56.3 |
63.5 |
65.3 |
214 |
267 |
229 |
1.33 |
1.65 |
1.79 |
6.2 |
6.2 |
7.8 |
|
21-24 |
60.1 |
68.1 |
69.0 |
181 |
219 |
176 |
1.39 |
1.65 |
1.63 |
7.7 |
7.5 |
9.3 |
|
Mean |
|
|
|
194 |
248 |
254 |
1.23 |
1.52 |
1.69 |
6.5 |
6.2 |
6.9 |
weight gains ranged from 1.25 to
1.50 kg. At the end of the sixteenth week the lambs weighed 3.2 kg less than
those kept on a high-level ration and it took them about four weeks longer to
reach the weight that the animals of the high-level feeding group had attained
at the age of 16 weeks (Finci, 1957). Thereafter their weekly weight gains
again fell off, coming to nought during the last week of the trial.
In a trial conducted in 1948 to
test the feasibility of raising Awassi lambs on a markedly restricted milk
diet, Volcani and Eyal (1954) recorded the weight gains of two groups of six
female lambs each, one group being pail-fed on a total of 50.3 kg of milk for
each lamb for 69 days, and the other group being suckled, each lamb consuming
81.6 kg of milk for 77 days. From the age of a week all lambs had free access
to a concentrate mixture and hay, and after weaning they were sent out to
pasture.
In a second test, made for the same
purpose in 1952, the weight gains of two groups of four female lambs each were
recorded, one group being bottle-fed on 39.4 kg of milk for each lamb for 45
days, followed by the addition of a milk replacer, while the lambs of the
control group were suckled for a period of 62 days, during which time they
consumed 80.6 kg of milk on an average. Concentrate and hay feeding was similar
to that in the first trial, the lambs consuming 40 g of concentrates a day at
the end of the third week, 100 g by the fourth week, 300 g at the age of two
months, and 500 g in the third month on average.
The weight gains of the lambs on
restricted milk feeding were inferior to those of the suckling lambs. The lambs
that obtained 50.3 kg of milk until weaning (Trial I) caught up with those on a
natural suckling regime only at 16 weeks of age, while those having 39.4 kg
until weaning (Trial II) were, at the age of six months, still 3 kg short of
the weight of the control group that had been suckled. The weights given in
Table 3-63 were recorded in the two trials.
In Cyprus the effect on growth rate
of suckling for 35 days or artificial rearing on a ewe milk replacer from the
first day of life has been studied in improved Awassi lambs of both sexes
(Cyprus ARI, 1973) (Table 3-64).
Prior to weaning, the growth rate
of lambs reared on the milk replacer was significantly lower than that of the
lambs suckled by their dams. When weaning weight was used as a covariate, the
difference in the post-weaning rate of growth was not significant.
The growth rate, feed requirements
and feed utilization of male Awassi lambs between the ages of five and ten
months have been studied by Folman, Eyal and Benjamin (1967) in three separate
feeding trials (Table 3-65). In one trial, two groups of lambs, and in both of
the other trials three groups, comprising 90 lambs in all, received different
quantities of feed (concentrates and either hay or cotton-seed hulls). The
combined results obtained in the three trials are given in Table 3-66.
In one of the three trials, which
was continued beyond 24 weeks, the number of feed units required for the
production of 1 kg additional live weight in group I rose to 10.1 during the
trial period 25-28 weeks, and to 10.5 during the fortnight 29-30 weeks. In
groups II and III the ratios of feed units to weight gain in these periods were
similarly wide.
The growth rate of
Awassi lambs may be negatively affected by a vitamin deficiency in an otherwise
well-balanced and adequate feeding ration. This has been shown by Folman (1963)
in a trial with two groups, each composed of 37 male Awassi lambs, that were
reared on the residual milk of their dams after milking and had free access to
hay and concentrates. For a period of ten weeks the concentrate mixture (A) given to one group included milk
powder and 70 000 IU of Vitamin A for each kilogramme, while that offered to
the other group (B) contained a similar percentage of protein but without the
Vitamin A compound. After this trial period both groups received the same
concentrate mixture (B) for four weeks. To this a Vitamin A and D compound was
added for both groups in the fourteenth week. The composition of the
concentrate mixtures is given in Table 3-67.
During the age period
of four to ten weeks thelambs of group A consumed 18.5 kg of concentrates and
9.7 kg of hay a head on average, and those of group B similar quantities,
namely 18.8 and 8.9 kg, respectively. At the age of 11-14 weeks the combined
groups consumed 19.0 kg of concentrates and 9.2 kg of hay a head. The growth
rates of the lambs of the two groups during these periods were as given in
Table 3-68. Table 3-69 gives the mean daily growth rate of the two groups of
lambs for the two experimental periods.
|
TABLE 3-67. (A)
Concentrate mixture with milk powder and Vitamin A |
(B) Concentrate mixture without milk powder and
Vitamin A |
||
|
Feedstuffs |
% |
Feedstuffs |
% |
|
Maize |
45.0 |
Barley |
53.0 |
|
Soya oilcake |
23.0 |
Soya oilcake |
25.0 |
|
Wheat bran |
15,0 |
Wheat bran |
20.0 |
|
Milk powder |
10.0 |
Di-calcium phosphate |
1.0 |
|
Carobs |
5.0 |
Salt |
1.0 |
|
Di-calcium phosphate |
1.0 |
|
|
|
Chalk |
0.5 |
|
|
|
Salt |
0.5 |
|
|
Source: Folman, 1963 | |||
TABLE 3-68.
Growth rates of male Awassi lambs fed different concentrate mixtures |
Age (weeks) |
Group A |
Group B |
|||
|
Live weight (kg) |
Weight increase per |
Live weight (kg) |
Weight increase per |
|||
|
fortnight (kg) |
day(g) |
fortnight (kg) |
day (g) |
|||
|
Birth |
5.6 |
— |
— |
5.4 |
— |
— |
|
2 |
8.8 |
3.2 |
229 |
8.5 |
3.1 |
221 |
|
4 |
12.3 |
3.5 |
250 |
11.9 |
3.4 |
243 |
|
6 |
16.3 |
4.0 |
286 |
15.6 |
3.7 |
264 |
|
8 |
20.6 |
4.3 |
307 |
19.9 |
4.3 |
307 |
|
10 |
24.2 |
3.6 |
257 |
22.8 |
2.9 |
207 |
|
12 |
28.9 |
4.7 |
336 |
25.2 |
2.4 |
171 |
|
14 |
33.5 |
4.6 |
329 |
28.2 |
3.0 |
214 |
Source: Folman, 1963 | ||||||
TABLE 3-69. Mean
daily weight increase of male Awassi lambs fed different concentrate mixtures |
Period |
Daily weight gain per
head (g) |
|
Group A |
Group B |
|
|
1-8 |
268 |
259 |
|
9-14 |
307 |
197 |
|
1-14 |
285 |
232 |
Source: Folman,
1963 | ||
|
TABLE 3-70. Effect
of environmental factors on weights of Awassi lambs
at birth, weaning and yearling age in Iraq (least squares means) |
||||||
|
Factor |
Age |
|||||
|
Birth |
Weaning |
1 year |
||||
|
No. |
Kg |
No. |
Kg |
No. |
Kg |
|
|
Year of birth |
||||||
|
1966 |
62 |
4.56 |
85 |
23.27 |
61 |
38.47 |
|
1967 |
84 |
4.87 |
92 |
16.09 |
49 |
39.37 |
|
1970 |
94 |
3.90 |
80 |
16.64 |
41 |
34.97 |
|
Total and average |
240 |
4.44 |
257 |
18.67 |
151 |
37.60 |
|
Sex of lamb |
||||||
|
Male |
126 |
4.56 |
130 |
19.25 |
78 |
41.49 |
|
Female |
114 |
4.32 |
127 |
18.09 |
73 |
33.71 |
|
Type of birth |
||||||
|
Single |
205 |
4.75 |
223 |
19.94 |
131 |
39.12 |
|
Twin |
35 |
4.13 |
34 |
17.40 |
20 |
36.08 |
|
Age of dam (years) |
||||||
|
1½ |
10 |
4.25 |
17 |
18.30 |
12 |
37.31 |
|
2½ |
58 |
4.39 |
60 |
18.65 |
34 |
36.20 |
|
3½ |
41 |
4.27 |
41 |
18.14 |
21 |
38.51 |
|
4½ |
55 |
4.68 |
57 |
19.27 |
31 |
39.13 |
|
5½ |
37 |
4.54 |
41 |
19.22 |
25 |
37.37 |
|
6½ |
22 |
4.44 |
21 |
18.43 |
16 |
37.37 |
|
7½ and above |
17 |
4.49 |
20 |
18.68 |
12 |
37.31 |
|
Month of birth |
||||||
|
November |
142 |
4.48 |
138 |
19.71 |
74 |
40.85 |
|
December |
63 |
4.70 |
70 |
19.62 |
48 |
40.04 |
|
January |
12 |
4.49 |
17 |
20.09 |
14 |
36.21 |
|
February |
7 |
4.64 |
14 |
16.81 |
11 |
32.11 |
|
March |
16 |
3.89 |
18 |
17.11 |
4 |
38.78 |
|
Source: Kazzal,1973 |
||||||
Folman (1963) attributed the
reduced growth rate of the lambs of group B for the age period of 9-12 weeks to
a Vitamin A deficiency. This was suggested by the absence of green fodder in
both rations, the relatively small quantities of milk consumed by the lambs
under the residue suckling regime — especially during the last weeks before
weaning — the requirements of larger quantities of Vitamin A by older lambs,
the faculty of the liver to store Vitamin A as evidenced by the lambs of group
A, and, most conspicuously, by the fact that the addition of a Vitamin A and D
compound to the ration of all lambs in the fourteenth week was followed by a
significant increase in the growth rate of the lambs of group B during this
period.
The effects of year of birth, sex
of lamb, type of birth, age of dam, and the month of birth on the body weights
of lambs at birth, weaning and yearling age were recorded by Kazzal (1973) for
a flock of Awassi sheep at Hammām Al'Alil Agricultural Experiment Station in
Iraq for three years (Table 3-70). Pre-weaning, post-weaning, and average daily
weight gains for the entire period of growth until yearling age are given in
Table 3-71.
The lambs were weaned at the age of
17 weeks and averaged a weight of 18.67 kg for both sexes (Kazzal, 1977). At
this time their body weight was significantly influenced by the year of birth,
reflecting differences in nutrition, climate and other factors that affect
growth rate. The influence of the month of birth on body weight was highly
significant. Lambs born in January were 0.38,0.47,3.28
and 2.98 kg heavier than lambs born in November, December, February and March,
respectively, and 1.42 kg heavier than the overall mean. Although the age of
the dam did not significantly affect the body weight of the lamb, there was a
general tendency for the weaning weight to increase with increases in the age
of dam up to 5½ years and then to decline at a higher age of the
dam (Kazzal, 1973).
The effect of the
year of birth on yearling weight was highly significant, although low in
relation
TABLE 3-71.
Pre-weaning, post-weaning and daily weight gains of Awassi lambs in Iraq (least
squares means) |
Factor |
No. |
Pre-weaning gain (kg) |
Post-weaning gain (kg) |
Average daily gain (g) |
|
Year of birth |
|||||
|
1966 |
45 |
19.93 |
13.44 |
91 |
|
|
1967 |
50 |
12.00 |
22.27 |
94 |
|
|
1970 |
41 |
14.53 |
16.28 |
84 |
|
|
Total and average |
136 |
15.49 |
17.33 |
90 |
|
|
Sex of lamb |
|||||
|
Male |
71 |
16.18 |
20.33 |
100 |
|
|
Female |
65 |
14.80 |
14.33 |
80 |
|
|
Type of birth |
|||||
|
Single |
117 |
16.07 |
17.90 |
93 |
|
|
Twin |
19 |
14.91 |
16.76 |
87 |
|
|
Age of dam (years) |
|||||
|
1½ |
6 |
15.39 |
18.73 |
94 |
|
|
2½ |
32 |
15.16 |
16.22 |
86 |
|
|
3½ |
22 |
15.49 |
18.51 |
93 |
|
|
4½ |
27 |
16.28 |
17.74 |
93 |
|
|
5½ |
24 |
16.06 |
16.25 |
89 |
|
|
6½ |
14 |
15.28 |
16.86 |
88 |
|
|
7½ and above |
11 |
14.76 |
17.02 |
87 |
|
|
Month of birth |
|||||
|
November |
74 |
15.71 |
20.92 |
100 |
|
|
December |
44 |
15.23 |
19.82 |
96 |
|
|
January |
10 |
17.53 |
14.57 |
88 |
|
|
February |
4 |
15.38 |
9.68 |
69 |
|
|
March |
4 |
13.60 |
21.67 |
97 |
|
Source: Kazzal, 1973 | |||||
to that observed at birth and
weaning. In 1967 yearling ewes were 3.5 kg heavier than ewes of similar age in
1970. The age of the dam and the month of birth also exerted less pronounced
effects on yearling body weights than at earlier ages. The age of the dam had
no significant effect on the body weight of yearlings. Lambs born in November
and December were heavier at yearling age than those born during the subsequent
three months because lambs born early in the lambing season had access to
spring pastures at pre-weaning and post-weaning age, whereas those born later
were too young to use the pasture forage available at that time. Also, lambs
born later in the season suffered from higher ambient temperatures and possibly
from greater infestation with internal parasites.
The year and month of birth were
responsible for significant variations in pre-weaning and post-weaning weight
gains as well as in the average daily gain from birth to yearling age (Kazzal,
1973).
At high summer temperatures and
intense solar radiation, such as are common in the southern parts of the range
of the Awassi, the growth of lambs is influenced by the provision or absence of
shade. At the Hofuf Agricultural Research Centre in Saudi Arabia, Pritchard and
Ruxton (1977) have investigated the effect of shade on growth and feed intake
of Awassi lambs (see Table 3-72).
Thirty-two female lambs in fleece,
recently weaned at the age of 4½ months and having an average live
weight of 30 kg, were divided into two equal groups of 16 each. All lambs were
kept in open pens with unshaded feed troughs and were offered an unlimited
quantity of green lucerne and 250 g of milled barley a day. They also had free
access to fresh water and a trace-mineralized salt block. One pen for one group
of the lambs was fitted with a timber frame thatched with palm leaves over a
quarter of its area, oriented so that shade was available at all times of the
day; the other pen was without shade.
The mean monthly
air temperatures for the two months of the 77-day trial were 31,8°C (22.3-41.3) in September and 26.4°C (17.2-35.9) in
October. The mean relative humidity in the two months was 34.0 percent
(17.7-58.5) and 37.3 percent (18.7-61.8), respectively. In July, August and
September, shade temperatures in the Saudi Arabian range of the Awassi can
exceed 45°C and the quantity of heat absorbed by lambs
exposed to the sun — even if protected by a full fleece against incoming
radiation — is potentially great.
The group of 16
lambs in the shaded pen had a 19 percent higher mean daily weight gain than the
group in the unshaded pen, the difference being significant. The lambs in the
unshaded pen consumed slightly more dry matter, but the difference was not
statistically significant. Feed conversion efficiency over the period of the
trial was 16 percent higher in the shaded than in the unshaded group (Pritchard
&Ruxton, 1977).
|
| |||||||||||||||||||||||||||||||||||||||||||||
Effect of sex. The effect of
sex on the weight gains of Awassi lambs is variable. The average body weights
of male and female İvesi lambs in Turkey, whether poorly or well-fed, show that
male lambs grow considerably faster than females (Tables 3-73 and 3-74).
Although nearly every test shows a
faster growth for male Awassi lambs than for females, the differences in weight
gains until weaning are not always statistically significant. In Lebanon, Ampy
and Rottensten (1968) found no significant difference between sexes in the
weaning weights of Awassi lambs at 60 days (Table 3-75). Under the nutritional
and managerial conditions of a research centre, season also had very little
influence on weaning weights. The small seasonal differences are attributed
mainly to different twinning rates (see Table 3-28), while the influence of
high summer day temperatures may have been modified by the rather low night
temperatures and low humidity during the day.
|
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
In Iraq, too,
Eliya and Juma (1970b) reported that, although male lambs slightly exceeded
females in daily weight gain until weaning at 120 days, the effect of sex on
weaning weight was not significant. The records of 11 male and eight female
single lambs at the Abu-Ghraib Experiment Station in 1967/68 showed a positive,
insignificant correlation between birth and weaning weights (Table 3-76).
In northern Iraq,
at the Hammām Al'Alii experiment farm of the University of Mosul, Ghoneim et
al. (1973) recorded the average weaning and yearling weights of male and
female, single and twin Awassi lambs for the years 1966/67 and 1967/68. Similar
to Eliya and Juma's (1970b) findings in
|
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
middle Iraq, they also found that while ram lambs were on
average 1 kg heavier than ewe lambs in weaning weight, the differences were not
statistically significant. But in yearling weight the males exceeded females by
an average of 9.7 kg and here the differences were highly significant (Table
3-77).
In Israel, Becker recorded
fortnightly weights for 39 male and 76 female Awassi lambs until weaned at the
age of eight weeks (Table 3-78). These results are not in accordance with the
majority of reports on weight increases in male and female Awassi lambs, which
show larger gains for males than for females (Table 3-79). The ratio of daily
weight increases between male and female lambs, which Becker recorded for the
highest individual daily weight gains, is more nearly in agreement with the
general experience on weight gains of male and female lambs.
Differences in weight gains between male and female lambs from birth to weaning and the age of 140 days were also found in Awassi lambs of Israeli derivation in Cyprus in 1970/71 (Table 3-80).
| |||||||||||||||||||||||||||||
|
TABLE 3-80. Weight gains of male and female Israeli
Awassi lambs from birth to weaning and 140 days |
||||||
|
Sexaia |
No. |
Birth weight (kg) |
Weaning weight (kg) |
Weaning age (days) |
140-day weight (kg) |
Daily weight gain |
|
Male |
32 |
5.3 |
15.7 |
44.6 |
35.9 |
219 |
|
Female |
22 |
5.0 |
14.8 |
42.0 |
33.6 |
204 |
|
Source: Cyprus
ARI, 1972 |
||||||
In Syria, at the
University of Aleppo School of Agriculture, 68 Awassi
lambs, weaned at an average age of 57 ±4.2 days, had a weaning weight of 18.8
kg for male lambs and 17.1 kg for female lambs. From birth to weaning the
average daily weight gain of male lambs was 330 g and of females 300 g
(Husnaoui & Fox, 1967).
Eyal and Goot (1960) recorded the live weights of male and female single lambs in two Awassi mutton flocks. The term 'mutton flock' in the husbandry of Awassi sheep denotes a flock in which the ewes are not milked but suckle their lambs in the manner of mutton breeds. In flock I the lambs had free access to a concentrate mixture, hay and some green fodder from the end of the first month. They consumed 200 g of concentrates a day on average during the second month and 300 g in the third month. In flock II the lambs were fed concentrates only from the middle of the second month on, at the end of which they consumed 250 g a day in addition to hay. At the end of the third month their average consumption of concentrates had increased to 400 g a day. The feeding of the ewes of flock I was superior to that of flock II which was maintained mainly on grazing. This is illustrated by the slower growth of the lambs—and more especially the males — of flock II in the first month. The mean live weights of male and female lambs were recorded and are given in Table 3-81.
|
TABLE 3-81. Mean live weights of Awassi at different ages in mutton
flocks (kg) |
||||||
|
Flock |
Sex |
No.
of lambs |
Age |
|||
|
Birth |
30 days |
60 days |
90 days |
|||
|
I |
Male |
22 |
4.81 |
14.05 |
22.87 |
30.05 |
|
II |
Male |
23 |
4.82 |
11.54 |
19.01 |
26.50 |
|
I |
Female |
17 |
4.26 |
12.90 |
20.63 |
26.34 |
|
II |
Female |
24 |
4.70 |
11.86 |
18.75 |
25.69 |
|
Average |
Male |
45 |
4.82 |
12.80 |
20.94 |
28.28 |
|
Female |
41 |
4.48 |
12.38 |
19.69 |
26.02 |
|
|
Source: Eyal & Goot, 1960 |
||||||
In
a mutton flock of improved Awassi sheep, in which the ewes were not milked and
the lambs joined their dams for 12 hours during the night until the age of
eight weeks, receiving unlimited quantities of concentrates and hay during this
period, the mean weights and weight gains of 15 male and 14 female single lambs
were recorded (Tables 3-82 to 3-84).
In a continuation
of this test, Folman, Eyal and Volcani (1960) investigated the effect of
different feeding levels on the growth of lambs, weaned at 16 weeks, from the
age of two to eight months. The lambs were divided into two groups, one of
which received a ration of 300 g of concentrates a head in addition to pasture
and their dams' milk, while the second group had to subsist on milk and pasture
alone. The monthly weights and daily weight gains of the two groups of lambs
were as given in Tables 3-85 and 3-86. Lambs weaned at four months did not suffer
any crisis from the withdrawal of milk at that age and their growth during the
first month after weaning proceeded normally.
In seven male and
seven female lambs (of the 15 males and 14 females in the trial), the
milk-to-weight-gain ratio during the first eight weeks of life was similar in
both sexes, namely 5:6 and 5:7 (Table 3-87). The correlation coefficients
between milk consumption and growth rate were high from birth to eight weeks,
and low from nine to 16 weeks (Table 3-88).
In another trial in a mutton flock the live weights of two groups of Awassi lambs, each consisting of eight males and eight females, were recorded at the mean ages of 66 and 120 days (Folman, Gaon & Shnurman, 1961). During the 54 days of the trial, one group of lambs had free access to a balanced concentrate mixture while the second group, composed of similar lambs, was restricted to 300 g of
| |||||||||||||||||||||||||||||||||||
| |||||||||||||||||||||||||
TABLE 3-85. Mean weights of Awassi lambs with (+) or without (-) concentrate
feeding |
Sex |
No. |
Feeding plane |
Mean weight (kg) at age (months) |
|||||
|
2 |
3 |
4 |
5 |
6 |
7 |
8 |
|||
|
Male |
7 |
(+) |
21.0 |
28.5 |
34.5 |
42.1 |
42.9 |
46.8 |
50.4 |
|
Female |
6 |
(+) |
19.4 |
26.5 |
31.3 |
38.4 |
39.6 |
41.5 |
46.2 |
|
Male |
8 |
(-) |
21.5 |
29.1 |
35.2 |
42.4 |
42.3 |
43.6 |
46.8 |
|
Female |
8 |
(-) |
18.6 |
24.5 |
28.5 |
33.7 |
34.3 |
38.1 |
38.9 |
Source: Folman, Eyal
& Volcani, 1960 | |||||||||
TABLE 3-86. Daily mean weight gains of lambs with (+) or without (-) concentrate
feeding |
Sex |
No. |
Feeding plane |
Daily weight gain during month of age (g) |
||||
|
3rd |
4th |
5th |
6th |
7th |
8th |
|||
|
Male |
7 |
(+) |
268 |
231 |
190 |
27 |
130 |
120 |
|
Female |
6 |
(+) |
254 |
185 |
178 |
40 |
63 |
157 |
|
Male |
8 |
(-) |
271 |
235 |
180 |
-3 |
43 |
107 |
|
Female |
8 |
(-) |
211 |
154 |
130 |
20 |
127 |
27 |
Source: Folman, Eyal
& Volcani, 1960 | ||||||||
|
Sex |
Age (weeks) |
|||||||||
|
1-2 |
3-4 |
1-4 |
5-6 |
7-8 |
5-8 |
1-8 |
9-12 |
13-16 |
1-16 |
|
|
Male |
4.67 |
6.34 |
5.34 |
5.93 |
6.15 |
5.96 |
5.63 |
5.70 |
5.18 |
5.52 |
|
Female |
4.18 |
6.63 |
5.13 |
6.92 |
5.86 |
6.34 |
5.68 |
6.48 |
5.58 |
5.76 |
concentrates
a head each day in the first month of the trial and 550 g in the second month.
In addition, the lambs received a daily ration of 250 g of hay a head and all
the milk of their dams. The male and female lambs of group I consumed 660 g of
concentrates a day and the lambs of group II 385 g on average. The weights were
recorded at the beginning and end of the trial, after the lambs had been kept
away from feed and water for 18-24 hours (Table 3-89). The trial showed that
the live weight of female Awassi lambs is affected less by a lower feeding
plane than that of male lambs whose capacity for growth in the third and fourth
months of life considerably exceeds that of females.
Other than in
Awassi mutton flocks in which the lambs are suckled for not less than four
months and their growth during this period is affected mainly by the feed added
to the milk of their dams, in improved dairy flocks the growth of lambs during
the first months of life is greatly influenced by the suckling regime. The
effects of different suckling regimes and feeding planes on the growth of
Awassi lambs in dairy flocks have been studied by several authors.
TABLE 3-89. Mean weights of male and
female Awassi lambs fed different amounts of concentrates |
|
Feeding plane |
Live weight at beginning of trial (kg) |
Live weight at end of trial (kg) |
Total weight gain (kg) |
Daily weight gain (g) |
|
Male |
High |
23.5 |
39.3 |
15.8 |
293 |
|
|
Low |
22.5 |
35.2 |
12.7 |
235 |
|
Female |
Difference |
–1.0 |
–4.1 |
–3.1 |
–58 |
|
|
High |
20.8 |
31.8 |
11.0 |
204 |
|
|
Low |
20.9 |
31.6 |
10.7 |
198 |
|
|
Difference |
+0.1 |
–0.2 |
–0.3 |
–6 |
Atzmon and Doron
(1951) examined the growth of female lambs under three suckling regimes which
differed in the relative periods of full and partial suckling until weaning at
60 days: group I —12 lambs, 14 days of full and 46 days of partial suckling;
group II —14 lambs, 28 days of full and 32 days of partial suckling; and group
III — 12 lambs, 60 days of full suckling.
The suckling lambs
stayed with their dams throughout the night. During the period of full suckling
the ewes were not milked, while at partial suckling they were milked in the
evening after return from pasture before their lambs joined them (see Table
3-90).
TABLE 3-90. Weight gains of female Awassi lambs under three suckling
regimes (kg) |
Age (weeks) |
Group |
||||
|
I |
II |
III |
||||
|
Mean weight |
Weekly weight gain |
Mean weight |
Weekly weight gain |
Mean weight |
Weekly weight gain |
|
|
Birth |
4.950 |
— |
4.300 |
— |
4.620 |
— |
|
1 |
7.370 |
2.420 |
6.400 |
2.100 |
6.590 |
1.970 |
|
2 |
9.540 |
2.170 |
8.560 |
2.160 |
8.800 |
2.210 |
|
3 |
11.720 |
2.180 |
10.730 |
2.170 |
10.860 |
2.060 |
|
4 |
14.120 |
2.400 |
12.900 |
2.170 |
12.970 |
2.110 |
|
6 |
18.250 |
2.065 |
16.600 |
1.850 |
16.930 |
1.980 |
|
8 |
21.560 |
1.655 |
20.500 |
1.950 |
20.940 |
2.005 |
|
12 |
24.550 |
0.748 |
23.460 |
0.740 |
23.230 |
0.573 |
|
16 |
28.800 |
1.063 |
27.600 |
1.035 |
27.300 |
1.018 |
|
20 |
32.800 |
1.000 |
30.800 |
0.800 |
30.300 |
0.750 |
|
24 |
35.200 |
0.600 |
33.700 |
0.725 |
33.000 |
0.675 |
Source: Atzmon &
Doron, 1951 | ||||||
Most of the lambs
were born in December and a very few in January. During the period of suckling
they received crushed barley, green clover, vetch hay and a concentrate
mixture, all of these ad libitum. From the age of three weeks to weaning
at 60 days they consumed 200 g of barley and concentrates, 150-200 g of hay and
1 kg of green clover a day on average. After weaning the lambs went out to
pasture. On their return they were given limited rations of concentrates and an
unlimited quantity of vetch hay and either green clover, maize or beetroot, of
which they consumed the average daily quantities listed in Table 3-91.
The lambs of group
I, in spite of the shortest period of full suckling, attained heavier weights
throughout the period of the test until the age of six months than the lambs of
the other two groups. This may be attributed to the larger milk production of
their dams — at first recording these yielded 1.950 kg a day versus 1.350 and
1.400 kg, respectively, in groups II and III — and to the higher mean birth
weights, as the heavier a lamb is at birth, the faster, generally, is its rate
of growth. Underwood, Shier and Cariss (1943) found that each 1-lb increase in
birth weight reduced the time necessary to reach (29.5 kg) live weight by 4½ to five days.
|
Month |
Concentrate mixture |
Green fodder |
Hay |
|
February |
250 |
700 |
200 |
|
March |
250 |
600 |
100 |
|
April |
225 |
900 |
100 |
|
May |
250 |
600 |
100 |
|
June |
250 |
600 |
150 |
|
July |
250 |
2 000 |
160 |
Source: Atzmon &
Doron, 1951 | |||
|
TABLE 3-92. Mean weights and weight gains in four groups of male Awassi lambs |
||||||||
|
Age (weeks) |
Group |
|||||||
|
1 (9 lambs) |
2 (10 lambs) |
3 (9 lambs) |
4 (5 lambs) |
|||||
|
Weight (kg) |
Daily gain |
Weight (kg) |
Daily gain (g) |
Weight (kg) |
Daily gain (g) |
Weight (kg) |
Daily gain (g) |
|
|
Birth |
5.06 |
— |
5.39 |
— |
5.34 |
— |
4.96 |
— |
|
1 |
7.17 |
301 |
7.67 |
326 |
7.46 |
303 |
7.05 |
299 |
|
2 |
8.99 |
260 |
10.01 |
334 |
9.62 |
309 |
8.76 |
244 |
|
3 |
11.03 |
291 |
12.20 |
313 |
11.68 |
294 |
10.44 |
240 |
|
4 |
13.22 |
313 |
14.63 |
347 |
14.00 |
331 |
12.21 |
253 |
|
5 |
14.76 |
220 |
16.26 |
233 |
15.43 |
204 |
14.36 |
307 |
|
6 |
15.95 |
170 |
17.67 |
201 |
16.72 |
184 |
16.49 |
304 |
|
7 |
17.55 |
228 |
18.64 |
139 |
17.99 |
181 |
18.63 |
306 |
|
8 |
19.02 |
210 |
20.30 |
237 |
19.59 |
229 |
20.42 |
256 |
|
9 |
20.67 |
236 |
22.21 |
273 |
20.80 |
173 |
21.64 |
174 |
|
10 |
22.20 |
219 |
24.21 |
286 |
21.48 |
97 |
22.57 |
133 |
|
11 |
23.94 |
249 |
25.24 |
147 |
22.83 |
193 |
23.69 |
160 |
|
12 |
25.97 |
290 |
27.63 |
341 |
24.40 |
224 |
25.11 |
203 |
|
13 |
28.12 |
307 |
29.27 |
234 |
25.83 |
204 |
26.48 |
196 |
|
14 |
30.12 |
286 |
30.52 |
179 |
27.53 |
243 |
28.00 |
217 |
|
15 |
31.64 |
217 |
32.20 |
240 |
28.82 |
184 |
30.25 |
321 |
|
16 |
33.25 |
230 |
34.48 |
326 |
30.41 |
227 |
32.19 |
277 |
|
Source: Doron, 1954a |
||||||||
The changeover
from full to partial suckling was hardly noticeable in the weekly weight gains
of groups I and II. But weaning at 60 days had a sharp effect on weights in the
ninth and tenth weeks, particularly in the lambs of group III which lost 120 g
in body weight during the tenth week of their lives.
Further tests on
the growth of male and female Awassi lambs under different suckling and feeding
regimes were conducted in 1952 and 1953 (Doron, 1954a). During the first two
weeks of the trials, the male lambs were suckled without restriction. During
the following four weeks they remained with their dams throughout the night
after the evening milking and in the seventh and eighth week they were allowed
one residue suckling of a few minutes' duration, about an hour after the ewes
had been milked. In addition to the milk, the lambs received 300-400 g of
concentrates a day and unlimited quantities of hay and green fodder. At the age
of two months they were divided into four groups. In groups 1, 2 and 3 one
residue suckling a day was continued until the end of the fourth month; the
lambs of group 4 were weaned at 60 days, at the then-customary time of weaning.
The lambs of group 1 received 600 g and those of group 2, 400 g of concentrates
each daily in addition to unlimited quantities of hay and green fodder. The
lambs of group 3 were given a daily concentrate ration of
400 g during the third month and 200 g during the fourth month. They were
pastured on green barley for seven hours a day and consumed 430 g of hay on
average after their return from pasture. The lambs of the control group, weaned
at 60 days, were pastured along with those of group 3 and provided with 250 g
of concentrates a day during the third and fourth months in addition to hay.
The mean weekly weight gains of the four groups until the age of 16 weeks were
as shown in Table 3-92.
The lambs of
groups 1 and 2 showed parallel growth from the fifth week on, that is, from the
time of transition from full to restricted suckling. At the age of four weeks
the lambs of group 2 were 1.4 kg heavier than those of group 1, a weight
difference that remained nearly static until the end of the trial. The lambs of
group 3 showed similar growth to those of group 1 until the age of eight weeks.
From then on they fell behind, mainly owing to the smaller concentrate ration
they received and possibly also because of their incapability of making full
use of the grazing to which they were transferred at the age of eight weeks.
The lambs of group 4 attained the highest mean weight of all four groups at the
age of eight weeks, in spite of their lowest mean birth weight. Thereafter
their daily weight gains dropped considerably, illustrating the favourable
effect on growth of both continued residue suckling and a high feeding plane,
such as maintained in groups 1 and 2.
The female lambs
included in the same trial were divided into three groups. During the first two
months the lambs of two of these were maintained on the same suckling regime as
the males of the trial, that is, on two weeks' full and four weeks' partial
(night) suckling, followed by one daily residue suckling during the seventh and
eighth weeks, which was continued until the termination of the trial at the end
of the sixteenth week. The female lambs of the control group were kept on the
same suckling and feeding regime as the two test groups until the end of the
sixth week, but they also continued partial (night) suckling during the last
two weeks of the second month, at the end of which they were weaned.
During the third
and fourth months the lambs of all three groups were pastured together with the
male lambs and received an unlimited quantity of hay on their return from
pasture. In addition, the lambs of group 1 were supplied with a concentrate
ration of 400 g during the third month (of which they consumed 370 g on
average) and 200 g (actual consumption 180 g) during the fourth month; those of
group 2 were supplied with 200 g of concentrates (actual consumption 180 g)
during the third and none during the fourth month; and the lambs of group 3,
weaned at 60 days, were given 250 g of concentrates a day during the third and
fourth months. The mean weight gains of the three groups until the age of 16
weeks were as given in Table 3-93.
The differences in
weight gain between the two sexes are significant. The male lambs of group 3
and the female lambs of group 1 were kept on a similar suckling and feeding
regime until the end of the trial. The weight differences to the advantage of
the male lambs were 690 g at birth, 2.22 kg at eight weeks, and 3.16 kg at 16
weeks. Again, the male lambs of group 4 and the female lambs of group 3 were
kept on the same suckling and feeding regime until the age of 16 weeks, having
been weaned at 60 days. Here, the mean birth weight of the females exceeded
that of the males by 310 g. At eight weeks the difference had been reversed.
The males were 260 g heavier than the females and at the age of 16 weeks the
difference had increased to as much as 4.74 kg in favour of the male lambs.
There are hardly
any differences in the weight gains of male and female Awassi lambs between the
first and second month of life. In some tests these were higher in the first
month and in others in the second month. Doron (1954b) recorded the mean weight
gain in three successive years (Table 3-94).
During the first
month, the milk of the dam supplies all the needs of the lamb. In the second
month the lamb already uses other feedstuffs in addition to milk. In one of the
tests, reported by Doron (1954b), male and female lambs, which on an average
consumed 150 g of concentrates, 200 g of hay and 500-1 000 g of green fodder
daily during the second month, required the quantities of milk shown in Table
3-95 for a 1-kg weight gain during the first two months.
Another set of
experiments designed to examine the growth rates of Awassi lambs under
different suckling regimes and on different feeding planes in a dairy flock was
conducted by Folman and Eyal (1961) and Folman, Eyal and Volcani (1966a, b, c).
In Experiment I, 28 male and female lambs were reared on a 12-hour suckling
regime until weaning at the age of eight weeks. In Experiment II, 36 lambs of
both sexes were tested under three different suckling regimes: 12-hour,
four-hour, and two residue sucklings a day, until weaning at nine weeks of age.
In Experiment III, 48 male and female lambs were divided into two groups, one
of which was kept on a four-hour suckling regime and the other one on two
residue sucklings a day until weaning at either 12 or 16 weeks. (For quantities
of milk consumed, see Tables 4-73 to 4-75.) In all these trials the lambs had
free access to concentrates and hay. In Experiment III the mean quantities of
concentrates consumed daily by each lamb are given in Table 3-96. The
performance of the lambs in the three trials was as shown in Table
|
TABLE
3-93. Mean weights and weight gains in three
groups of female Awassi lambs |
||||||
|
Group |
||||||
|
Age (weeks) |
1 (13 lambs) |
2 (13 lambs) |
3 (11 lambs) |
|||
|
Weight (kg) |
Daily gain (g) |
Weight (kg) |
Daily gain (g) |
Weight (kg) |
Daily gain (g) |
|
|
Birth |
4.65 |
_ |
4.89 |
— |
5.27 |
— |
|
1 |
6.46 |
259 |
6.61 |
246 |
7.05 |
254 |
|
2 |
8.25 |
256 |
8.79 |
311 |
8.52 |
210 |
|
3 |
10.01 |
251 |
10.26 |
210 |
10.24 |
246 |
|
4 |
11.86 |
264 |
12.55 |
327 |
12.12 |
269 |
|
5 |
13.52 |
237 |
14.12 |
224 |
14.10 |
283 |
|
6 |
14.72 |
171 |
15.22 |
157 |
16.06 |
280 |
|
7 |
15.89 |
167 |
16.48 |
180 |
18.15 |
299 |
|
8 |
17.37 |
211 |
18.07 |
227 |
20.16 |
287 |
|
9 |
18.98 |
230 |
19.56 |
213 |
20.93 |
110 |
|
10 |
19.91 |
133 |
20.38 |
117 |
21.81 |
126 |
|
11 |
21.32 |
201 |
21.39 |
144 |
22.71 |
129 |
|
12 |
22.48 |
166 |
22.66 |
181 |
23.60 |
127 |
|
13 |
23.75 |
181 |
23.96 |
186 |
24.40 |
114 |
|
14 |
25.00 |
179 |
24.90 |
134 |
25.33 |
133 |
|
15 |
26.14 |
163 |
25.97 |
153 |
26.25 |
131 |
|
16 |
27.25 |
159 |
26.82 |
121 |
27.45 |
171 |
|
Source: Doron, 1954a |
||||||
3-97. The
fortnightly weights until the age of eight weeks of the lambs in Experiment I
were as given in Table 3-98.
The mean daily
weight increase of each lamb until the age of eight or nine weeks varied
between 168 and 329 g in
males and 162 and 280 g in
females, in correlation with the quantities of milk consumed by the lambs. The
efficiency of milk utilization was inversely related to the amounts consumed
(Table 3-99). In male lambs, the mean milk-to-weight-gain ratios ranged from
3:3 to 5:0 and in female lambs from 4:3 to 6:3. Extension of residue suckling
to the third and fourth months produced no significant effect of the different
quantities of milk consumed by the lambs on their rate of gain (Tables 3-100
and 3-101).
The weight gains
of lambs suckled in the course of 12 hours a day exceeded those attained by
lambs reared on a four-hour regime or on the residual milk of their dams after
milking (Table 3-102). Up to 12 weeks of age there was no difference in the
weight gains between lambs obtaining one or two residues, whereas considerable
differences were found between these groups in weeks 13-16. The lack of
significant differences between one and two residue sucklings at the age of
9-12 weeks indicates that with an average daily concentrate consumption of 530 g in addition to hay there is no
want of energy
| |||||||||||||||||||||||||||||||||||
| |||||||||||||||||||||||||||||||||||||
TABLE 3-97. Weight gains of lambs under different suckling regimes from birth to 8 or 9 weeks in an Awassi dairy flock |
Experiment |
Group |
Suckling regime |
Sex |
No. |
Mean
weight at weeks |
Daily
weight gain (wks) |
Total
milk consumption (wks) |
|||
|
Birth
(kg) |
8
(kg) |
9
(kg) |
1-8
(g) |
1-9
(g) |
1-8
(kg) |
1-9
(kg) |
|||||
|
I |
|
12
hours |
♂ |
13 |
4.2 |
20.7 |
— |
295 |
— |
78 |
— |
|
♀ |
15 |
3.7 |
18.7 |
— |
268 |
— |
78 |
— |
|||
|
II |
1 |
12
hours |
♂ |
4 |
4.8 |
— |
25.5 |
— |
329 |
— |
101 |
|
♀ |
8 |
4.8 |
— |
22.4 |
— |
280 |
— |
111 |
|||
|
2 |
4
hours |
♂ |
6 |
5.8 |
— |
19.7 |
— |
221 |
— |
53 |
|
|
♀ |
6 |
5.2 |
— |
16.6 |
— |
180 |
— |
50 |
|||
|
3 |
2
residues |
♂ |
8 |
5.5 |
— |
16.1 |
— |
168 |
— |
51 |
|
|
♀ |
4 |
5.5 |
— |
15.7 |
— |
162 |
— |
48 |
|||
|
III |
1 |
4
hours |
♂ |
8 |
5.7 |
19.4 |
— |
245 |
— |
58 |
— |
|
♀ |
16 |
5.3 |
17.1 |
— |
211 |
— |
52 |
— |
|||
|
2 |
2
residues |
♂ |
11 |
5.7 |
20.9 |
— |
271 |
— |
50 |
— |
|
|
♀ |
13 |
5.1 |
16.9 |
— |
211 |
— |
50 |
— |
|||
TABLE 3-99. Milk-to-weight-gain
ratio, weeks 1-8 or 1-9 (Experiments
I—III) |
Experiment |
Group |
Suckling
regime |
Sex |
Weeks |
|
|
1-4 |
5-8 |
1-8/1-9 |
||||
|
I |
|
12
hours |
♂ |
4:8 |
5:2 |
5:0 |
|
♀ |
5:0 |
5:5 |
5:2 |
|||
|
II |
1 |
12
hours |
♂ |
4:6 |
5:1 |
4:8 |
|
♀ |
6:1 |
6:6 |
6:3 |
|||
|
2 |
4
hours |
♂ |
4:7 |
3:7 |
3:8 |
|
|
♀ |
4:9 |
4:4 |
4:4 |
|||
|
3 |
2
residues |
♂ |
4:4 |
5:2 |
4:8 |
|
|
♀ |
4:4 |
5:1 |
4:7 |
|||
|
III |
1 |
4
hours |
♂ |
4:7 |
3:8 |
4:2 |
|
|
♀ |
4:7 |
4:2 |
4:4 |
||
|
2 |
2
residues |
♂ |
4:2 |
2:4 |
3:3 |
|
|
|
♀ |
4:8 |
3:7 |
4:3 |
||
even on a low-milk diet during this period in which the lambs are capable of
supplying their requirements from feeds other than milk. Consequently, the
differences in the weight gains of lambs between one and two residue sucklings
at the age of 13-16 weeks are not attributed to differences in energy intake,
but may possibly be owing to inherent differences in the Vitamin A supply.
In nearly every trial the
milk-to-weight-gain ratio was narrower in male lambs than in female lambs.
Generally, the milk-to-weight-gain ratio was wider in suckling regimes providing
larger quantities of milk. This was particularly evident during the later weeks
(9-16) of the suckling period. In the 12-hour suckling regime in a flock of
exceptionally good milking ewes, the lambs were incapable
TABLE 3-100. Weight
gains of Awassi lambs under different suckling regimes from 9 to 16 weeks (continuation of Experiment III) |
Suckling regime |
Sex |
Mean weight at week |
Daily weight gain (wks) |
Total milk consumption (wks) |
|||
|
8 (kg) |
12 (kg) |
16 (kg) |
9-12 (g) |
13-16 (g) |
9-12 (kg) |
13-16 (kg) |
||
|
1 residue |
♂ |
20.8 |
28.8 |
— |
286 |
— |
7.7 |
— |
|
♀ |
16.8 |
21.9 |
— |
182 |
— |
9.3 |
— |
|
|
2 residues |
♂ |
21.2 |
29.4 |
— |
293 |
— |
19.6 |
— |
|
♀ |
17.1 |
22.4 |
— |
189 |
— |
19.0 |
— |
|
|
1 residue |
♂ |
— |
25.5 |
30.5 |
— |
179 |
— |
8.4 |
|
♀ |
— |
21.5 |
24.0 |
— |
89 |
— |
4.5 |
|
|
2 residues |
♂ |
— |
27.5 |
35.0 |
— |
268 |
— |
20.1 |
|
♀ |
— |
21.0 |
25.7 |
— |
168 |
— |
15.8 |
|
| |||||||||||||||||||
TABLE 3-102. Correlation coefficient between milk consumption and
weight gain of lambs |
Experiment |
Group |
Suckling regime |
Age (weeks) |
||||
|
1-4 |
5-8 |
1-8/1-9 |
9-12 |
13-16 |
1-16 |
|||
|
I |
|
12 hours |
0.80 |
0.63 |
0.86 |
— |
— |
— |
|
II |
1 |
12 hours |
0.44 |
0.05 |
0.35 |
— |
— |
— |
|
2 |
4 hours |
0.83 |
0.77 |
0.84 |
— |
— |
— |
|
|
3 |
2 residues |
0.94 |
0.62 |
0.73 |
— |
— |
— |
|
|
II |
1 |
4 hours |
0.67 |
0.03 |
0.48 |
— |
— |
— |
|
2 |
2 residues |
0.28 |
0.05 |
0.21 |
— |
— |
— |
|
|
3 |
1 residue |
— |
— |
— |
0.08 |
— |
— |
|
|
4 |
2 residues |
— |
— |
— |
0.07 |
— |
— |
|
|
5 |
1 residue |
— |
— |
— |
— |
0.94 |
0.79 |
|
|
6 |
2 residues |
— |
— |
— |
— |
0.22 |
0.58 |
|
of using the large quantities of milk they sucked (101 and 111 kg,
respectively) efficiently. In the majority of tests with limited suckling, the
milk-to-weight-gain ratios for weeks 5-8 were narrower than for weeks 1-4. In
these respects Awassi lambs do not differ from thin-tailed mutton breeds;
similar results have been reported by Barnicoat, Logan and Grant (1949),
Thomson and Thomson (1953), Guyer and Dyer (1954) and Owen (1957).
Correlation coefficients were high and
statistically significant in lambs that received small or medium quantities of
milk. The small coefficient in one of the 12-hour suckling regimes illustrates
the insufficient utilization of the excessive quantity of milk consumed by the
lambs of this group. Similarly small correlation coefficients in Experiment III
are attributed to the large quantities of concentrates consumed by these lambs,
which made them less dependent on milk. In all experiments the coefficients for
the second month were smaller than those for the first month after birth.
In previous studies (Folman, Eyal &
Volcani, 1960; Edelman, 1963)
it was found that weaning Awassi lambs at eight weeks led to a considerable
retardation of growth in comparison with lambs that were suckled over a longer period. Subsequent studies (Folman, 1963; Folman,
Eyal & Volcani, 1966c), however, showed that the milk consumed by the lambs
in the third and fourth months could be replaced by a suitable concentrate
mixture. However, this is not always economical, for the residual milk
obtainable by the suckling lamb after the second month is not recoverable by
milking. Hence, Folman, Eyal and Volcani (1966c) concluded that continuation of
residue suckling during the third month depends on the respective costs of feed
supplied to the lambs or ewes and that 'the extension of the suckling period
over the fourth month does not seem to be justified under any conditions'.
In their study (1960), Folman, Eyal and
Volcani investigated the effects of weaning at eight weeks and of different
feeding planes on the growth of Awassi lambs from the age of two to eight
months in an improved dairy flock. One group of male and female lambs received,
in addition to pasture, quantities of a concentrate ration consisting of
one-third grain, one-third bran and one-third oilcake for 100 days and a ration
of oilcake for another 70 days, while the second group of male and female lambs
was pastured without any additional feed (Table 3-103). The monthly weights and
daily weight gains of the two groups of lambs were as shown in Tables 3-104 and
3-105.
The daily quantity of 300 g of concentrates was insufficient to compensate
for the withdrawal of milk at weaning at 56 days of age, but compared with the
lambs that were pastured without supplementary concentrates, the additional
concentrate ration minimized the crisis and the daily weight gain of these
lambs during the first critical month after weaning exceeded that of the lambs
fed only on pasture by 39 g, or 134 percent in males and 156 percent in
females. After the month of crisis the lambs were capable of making full use of
pasture and the percentage of the difference in daily weight gains between the
two groups became much smaller.
The depth of the crisis which lambs kept on
pasture without supplementary concentrate ration undergo in the first month
after weaning at eight weeks can also be gauged by a comparison of their weight
gains in this month with those of lambs in a mutton flock (see Tables 3-85 and
3-86) kept under similar conditions, but weaned at four months. While male
Awassi lambs weaned at four months gained 271 g a day in their third month of life, those weaned
at eight weeks gained only 29 g a day
in the third month. The comparative figures for female lambs are 211 and 25 g.
TABLE 3-104. Mean weights of lambs with (+) or without (-) concentrate feeding (kg) |
Sex |
No. |
Feeding plane |
Mean weight at age (months) |
|||||
|
Weaning |
3 4 5 6 7 8 |
||||||||
|
Male |
5 |
(+) |
20.7 |
22.6 |
26.6 |
34.0 |
36.1 |
39.1 |
42.6 |
|
Female |
9 |
(+) |
18.5 |
20.3 |
24.1 |
29.5 |
30.7 |
34.0 |
36.8 |
|
Male |
7 |
(-) |
20.2 |
21.0 |
24.0 |
29.1 |
31.2 |
34.0 |
37.9 |
|
Female |
6 |
(-) |
18.9 |
19.6 |
22.8 |
27.9 |
29.0 |
30.7 |
33.8 |
TABLE 3-105. Mean daily weight gains of lambs with (+) or without (-) concentrate
feeding |
Sex |
No. |
Feeding plane |
Daily weight gain during month of age (g) |
||||
|
3rd |
4th |
5th |
6th 7th 8th |
|||||
|
Male |
5 |
(+) |
68 |
154 |
185 |
70 |
100 |
117 |
|
Female |
9 |
(+) |
64 |
146 |
135 |
40 |
110 |
93 |
|
Male |
7 |
(-) |
29 |
115 |
127 |
70 |
93 |
130 |
|
Female |
6 |
(-) |
25 |
123 |
128 |
37 |
57 |
103 |
Even at the age of eight months, the lambs
that had been weaned at eight weeks had not overcome the retardation in growth
resulting from weaning at this early age. Lambs weaned at four months, but
otherwise kept on similar feeding planes, still weighed 5-9 kg more at eight
months. Nor did the addition of concentrates from the third to the eighth month
to the feed of lambs weaned at eight weeks fully compensate for the milk
obtained by lambs in a mutton flock in the third and fourth months before
weaning. At the age of eight months lambs weaned at eight weeks and thereafter
fed concentrates plus pasture still weighed 4.2 kg (males) and 2.1 kg (females)
less than lambs weaned at four months and pastured without a concentrate
supplement.
Single- and twin-born lambs. Differences
in growth rate during the early period of life between single and twin Awassi
lambs are mainly a result of the lower birth weights of twins. In Awassi sheep
other than in the improved dairy type, differences may also be from an
insufficient share of the milk that twins receive from their dams.
In Cyprus, single and twin Awassi lambs of
both sexes, derived from stock imported from Israel, showed the average weight
gains from birth to 140 days in 1970/71 and 1971/72 given in Table 3-106. In a
stationary Awassi flock at the American University farm in Lebanon, Rottensten
and Ampy recorded the mean weight gains from birth to weaning at 60 days of
male and female, single and twin lambs for the years 1955-63 (Table 3-107).
| |||||||||||||||||||||||||||||||||||||||||||
In Turkey, a series of trials with pure-bred
ívesi,
Kivircik and Sakiz and
cross-bred Ívesi-East Friesian and
Kivircik-East Friesian lambs under different systems of rearing were conducted
by Lischka (1976) at the experimental farm of the Ege University, Bornova/ízmir
in Menemen in 1972-74. Birth, 30-, 60- and 90-day weights were recorded
separately for male and female, single and twin lambs that were suckled by
their dams for two months or that were separated from them after two days and
reared on a milk replacer in
a self-feeder or on cow milk in bottles to a weight of 10-12 kg. During the
trial the lambs had free access to concentrates and water (see Table 3-108).
The data recorded by Lischka show that
single-born lambs were heavier than twins throughout the test period. The lambs
suckled by their dams had the highest growth rates and those reared on cow milk
the lowest.
In Iraq, Karam et al. (1971) found that 66.8 percent of the
variation in the weaning weight of
|
TABLE 3-108. Average birth, 30-, 60- and 90-day-weights of Awassi lambs in Turkey under three systems of rearing |
|||||||||||
|
|
(a) Suckled until the age of 2 months |
||||||||||
|
(b) Reared on a milk replacer after 2 days of suckling |
|||||||||||
|
(c) Reared on cow milk after 2 days of suckling |
|||||||||||
|
Weight |
|||||||||||
|
Type of birth |
Sex |
Birth |
30 days |
60 days |
90 days |
||||||
|
No. |
Kg |
No. |
Kg |
No. |
Kg |
No. |
Kg |
||||
|
(a) |
Single |
Male |
34 |
4.91 |
34 |
13.86 |
34 |
21.56 |
32 |
26.85 |
|
|
Female |
23 |
4.88 |
23 |
13.00 |
23 |
20.52 |
22 |
24.99 |
|||
|
|
Twin |
Male |
7 |
4.47 |
7 |
10.97 |
7 |
17.33 |
7 |
23.69 |
|
|
Female |
12 |
4.10 |
12 |
10.45 |
12 |
16.21 |
12 |
21.56 |
|||
|
(b) |
Single |
Male |
11 |
4.62 |
11 |
10.74 |
11 |
17.01 |
9 |
24.78 |
|
|
Female |
11 |
4.12 |
11 |
10.23 |
11 |
16.25 |
3 |
19.69 |
|||
|
|
Twin |
Male |
4 |
3.71 |
4 |
10.37 |
4 |
15.73 |
4 |
23.79 |
|
|
Female |
2 |
3.73 |
2 |
9.55 |
2 |
16.45 |
— |
— |
|||
|
(c) |
Single |
Male |
1 |
5.35 |
1 |
8.00 |
1 |
12.00 |
1 |
18.60 |
|
|
Female |
6 |
5.10 |
6 |
9.17 |
6 |
16.08 |
1 |
18.45 |
|||
|
Source: Lischka, 1976 |
|||||||||||
Awassi lambs was
attributable to the birth weight of the lambs and to the milking ability of
their dams. The weight gains from birth to weaning at 12 weeks were recorded in
male and female, single and twin lambs at the Abu-Ghraib Experiment Station in
1969 (see Table 3-109).
In the improved Awassi dairy type, single lambs do not always
surpass twins in daily weight gains. Data recorded in Iran in 1967-70 show
larger daily gains from birth to weaning in male twins derived from stock
imported from Israel than in single male lambs (Table 3-110). At the same time
single female lambs exceeded twins in daily gains during this period. Weighings
of the same lambs from weaning to about six months showed that not only did the
male twins exceed singles in daily weight gains, but the same phenomenon was
observed in the females in the post-weaning period (Wallach & Eyal, 1974).
|
TABLE 3-109. Weight gains from
birth to weaning in male and female single and twin Awassi lambs in Iraq |
|||||
|
Sex |
Type of birth |
No. |
Birth
weight (kg) |
Weaning
weight (kg) |
Daily
weight gain (g) |
|
Male |
Single |
12 |
4.76 |
22.29 |
209 |
|
|
Twin |
11 |
3.62 |
16.94 |
159 |
|
Female |
Single |
10 |
4.11 |
19.11 |
179 |
|
|
Twin |
7 |
3.71 |
17.56 |
165 |
|
Source: Karam et al., 1971 |
|||||
|
TABLE 3-110. Mean weights and
weight gains of male and female single and twin Israeli Awassi lambs in Iran |
|||||||
|
Sex |
Type of birth |
No. |
Birth
weight (kg) |
Weaning
weight (kg) |
Weaning
age (days) |
Daily
weight qains from |
|
|
birth
to weaning (g) |
weaning
to с 6 months (g) |
||||||
|
Male |
Single |
144 |
5.1 |
29.1 |
89 |
269 |
248 |
|
|
Twin |
36 |
4.3 |
30.3 |
92 |
283 |
254 |
|
Female |
Single |
135 |
4.8 |
25.9 |
90 |
234 |
170 |
|
|
Twin |
50 |
4.2 |
23.9 |
88 |
224 |
192 |
In the first
fortnight, the lambs stayed with their dams which were not milked during this
time. Thereafter the ewes were milked twice a day. After each milking the lambs
had access to their dams for residue suckling. During the third week they
joined the ewes for six hours a day, during the fourth and fifth weeks for four
hours, the sixth week three hours, in the seventh and eighth weeks two hours,
and in the ninth week for one hour a day. During the tenth week the lambs were
allowed one residue suckling of 30 minutes, in the eleventh and twelfth weeks
15 minutes, and from the thirteenth to the sixteenth week five minutes a day.
In addition to their dams' milk, the lambs received a daily ration of 200-300 g of hay and an unlimited quantity
of concentrates.
Twin lambs with
mean birth weights below those of single lambs usually require a longer period
to reach a particular weight than do single lambs of the same sex and they may
not come up to the weight of the latter until they are well over a year old.
The differences in growth rate between the sexes and between single and twin
lambs are illustrated by mean daily weight gains up to the age of ten weeks as
well as by the mean weights at the ages of seven and 16 weeks and five and 12
months, as recorded by Goot (1966) in an experimental flock of improved Awassi
dairy sheep during the years 1956/57-1960/61 (Tables 3-111 to 3-113).
Effect of
docking. The effect of docking on the growth of Awassi lambs
has been studied by McLeroy, Ananian and Kurdian (1959), Epstein (1961), Asker,
El-Khalsy and Juma (1964) and Farhan, Al-Khalisi and Hameed (1969).
In an experiment
undertaken in Lebanon at the experimental farm of the American University of
Beirut to ascertain the effect of docking on the growth of male Awassi lambs
from birth to weaning at three to six months, McLeroy, Ananian and Kurdian
compared 19 lambs docked at birth with 19 intact control sheep.
|
| |||||||||||||||||||||||||||||||||||||||||||||
TABLE 3-113. Mean weights of female single and twin
Awassi lambs at 5 and 12 months (kg) |
Type of birth: |
Single
(48 lambs) |
Twin
(12 lambs) |
|
|
Age (months): |
5 |
12 |
5 |
12 |
|
Weight: |
25.9 |
37.4 |
24.1 |
36.4 |
Although the
intact lambs were 3.057 kg heavier at the time of slaughter than the docked
lambs (see Table 5-16), the difference was not statistically significant. Nor
was there any indication that docked lambs fared differently from normal ones
during poor sheep years. Hence the authors concluded that under the conditions
of their experiment, docking did not materially influence live weight.
In Israel, Epstein
(1961) recorded the live weights of 12 docked and 12 intact male Awassi lambs
which were all sired by the same ram. The dams of 16 lambs were aged ewes which
had previous maximum milk records ranging from 278 to 460 kg. The dams of the
remaining eight lambs were progeny of these ewes. The new-born lambs, twins
included, were arranged in pairs. One of each pair was selected at random and docked ; the other was left undocked for control. While two
pairs of male twins were thus separated, one of each pair being docked, three
male lambs with twin sisters chanced to be included among the undocked
controls. The lambs and their dams were kept on natural pasture in an uprooted
orange grove for about seven hours a day. After their return from pasture and
throughout the night the animals had free access to drinking water and a salt
lick. The ewes received an additional concentrate ration of 300 g a head, while the lambs had free access
to a similar concentrate mixture in a creep. The ewes were not milked, suckling
their lambs throughout the trial.
The lambs were
weighed at birth and on the following three days at the same hour. On the third
day after birth half the lambs were docked immediately after weighing, being
already fairly strong to stand docking, while the lateral skin folds of the
tail were still empty of fat. The folds on either side of the tail were cut
with a scalpel in the direction of the tail butt, as close to the body as
possible since small remnants of skin folds later turn into large reservoirs of
fat. This part of the process caused the loss of only a few drops of blood. The
tail was then docked between the first and second caudal vertebrae. In order to
prevent an undue loss of blood, a loop of string was tied around the tail prior
to docking, and removed an hour after the operation. The wound was dusted with
an antiseptic powder. No lamb died as a result of the operation, although some
of them showed discomfort for the rest of the day. The weight of the docked
tail was recorded. Daily weighing of the lambs was continued for three more
days, and thereafter on the fourteenth, twenty-first, thirtieth, sixtieth, and
ninetieth day after birth. The lambs were then deprived of feed for 18 hours
and weighed empty (see Table 3-114 and 3-115).
The docking of the
fat tail had a small negative effect on the weight of the lambs in all periods.
Although the actual weight loss occurred on a single day, the lambs never fully
recovered the relapse in comparison with the undocked controls. Docking
materially affected the average daily weight gain in the first month, the
difference being 37 g in
favour of the undocked lambs. The disadvantage, while persisting, fell to a
daily average of 7 g in the
second month, and 6 g in the
third. Altogether the retrogression was slight, the weight difference at the
age of 91 days amounting to only 300 g, or about 1 percent of the weight of the
undocked lambs. Nevertheless, the retardation in growth caused by docking was
not immaterial in view of two circumstances: (1) The
average birth weight of the undocked lambs was 600 g below the average of the lambs to be
docked. On the third day, shortly before docking, the mean weight difference
had decreased by one-third, but the control sheep still weighed 400 g less on average. (2) Among the
undocked lambs there were three more twins that had to share their dams' milk
with their sisters.
In Iraq, 40 single male Awassi lambs from the Abu-Ghraib Experiment Station were divided into
|
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
TABLE 3-116.
Mean weights of undocked and docked male Awassi lambs in Iraq from birth to
13 months (kg) |
Group of lambs |
Age
(months) |
||||||||||||
|
Birth |
1 |
2 |
3 |
4 |
5 |
6 |
7 |
8 |
9 |
10 |
11 |
12 |
13 |
|
|
Undocked |
4.76 |
12.0 |
14.5 |
17.5 |
29.0 |
32.7 |
36.9 |
37.1 |
39.8 |
41.4 |
40.1 |
39.0 |
37.4 |
42.3 |
|
Docked |
4.69 |
10.6 |
12.7 |
15.6 |
26.8 |
29.8 |
34.0 |
33.4 |
35.1 |
38.3 |
35.8 |
33.7 |
33.2 |
38.1 |
|
Difference |
||||||||||||||
|
kg |
0.07 |
1.4 |
1.8 |
1.9 |
2.2 |
2.9 |
2.9 |
3.7 |
4.7 |
3.1 |
4.3 |
5.3 |
4.2 |
4.2 |
|
% |
1.47 |
11.7 |
12.4 |
10.8 |
7.5 |
8.9 |
7.9 |
9.9 |
11.8 |
7.5 |
10.7 |
13.5 |
11.2 |
9.9 |
Source: Asker, El-Khalsy & Juma, 1964 | ||||||||||||||
two groups
of 20 each. The lambs of one group were docked with rubber rings before they
were two weeks old, while those of the other group served as control animals.
The lambs stayed with their dams until weaning at four months. After weaning
they were kept on good hay until the age of ten months. This was followed by a
fattening period of two months during which the lambs received a balanced concentrate
mixture in addition to hay and straw. At the beginning of the fattening period
they consumed 250 g of
concentrates a day on average and after four weeks 1 kg (see Table 3-116).
With the advance
in age of the lambs, the trial showed an increasing, statistically significant
superiority in the body weight of the undocked to the docked animals
(Fig.
3-17). The weight differences during the lambs' life ranged from 1.4 to 5.3 kg,
being especially pronounced during the first few months after docking and also
in the first month of the fattening period. The undocked lambs gained about
24.2 kg from birth to weaning or 195 g a day, while the docked lambs gained only 22.1 kg, or 172 g a day, in the same period. After
weaning the mean daily weight gains of the lambs of the two groups decreased to
86 and 68 g, respectively, while the total gains from weaning to eight months
came to 10.8 and 8.3 kg. After the ninth month lamb weights dropped, mainly as
a result of shearing (Asker, El-Khalsy & Juma, 1964).
In a further study
of the effect of docking on the growth and carcass of male Awassi lambs at
Abu-Ghraib, Farhan, Al-Khalisi and Hameed (1969) found that docking reduced the
average daily weight gain of lambs by 23.4 percent (Table 3-117). With a total
feed intake of 24.8 kg for each 1-kg weight gain, the docked lambs were
inferior in feed conversion to the undocked ones which required only 20.7 kg of
feed for a 1-kg weight gain.
Figure 3-17. Weights of undocked and docked Awassi lambs. (Source: Asker, El-Khalsy & Juma, 1964)
|
TABLE 3-117. Feedlot responses of
docked and normal Awassi lambs |
||
|
Docked |
Normal |
|
Number of lambs |
5 |
9 |
|
Feeding period (days) |
81 |
81 |
|
Average initial weight (kg) |
35.3 |
38.2 |
|
Average final weight (kg) |
44.2 |
49.7 |
|
Average daily weight gain (g) |
308 |
369 |
|
Feed intake per 1 -kg weight gain |
|
|
|
Green lucerne
(kg) |
8.8 |
7.0 |
|
Concentrates (kg) |
16.0 |
13.7 |
|
Source: Farhan,
Al-Khalisi & Hameed, 1969 |
||
The development of the Awassi lamb,
as expressed by changes in body conformation and shape of the growing animal,
is mainly a function of the individual growth rate which, again, depends on
sex, single or multiple birth, suckling regime and
plane of nutrition.
Little data are
available on the development of Awassi lambs. Volcani and Eyal (1954) recorded
the changes in withers height in two groups of six female lambs each from the
age of one week to nine months. The lambs of the two groups were reared on
different quantities of milk, one group being pail-fed on 50.3 kg of milk for
each lamb for 69 days, while the lambs of the other group were suckled, consuming 81.6 kg of milk on average over 77 days
(see p. 115). The mean withers heights and live weights of the two groups were
as shown in Table 3-118.
An indication of
the allometric growth of male and female Awassi sheep is given by the mean
values of a total of over 4 000 measurements of different parts of the body,
taken of sheep of different age groups in three improved dairy flocks in Israel
in 1977/78 (Tables 3-119 to 3-121) (Epstein, unpublished).
TABLE 3-118. Withers heights
and live weights of female Awassi lambs reared on different quantities of milk |
Age |
|
Pail-fed
lambs (50.3 kg milk) |
Suckling
lambs (81.6 kg milk) |
|||
|
Height
(cm) |
Weight
(kg) |
Weight-height
ratio (%) |
Height
(cm) |
Weight
(kg) |
Weight-height
ratio (%) |
||
|
Weeks |
1 |
38.2 |
5.25 |
100.0 |
40.0 |
5.43 |
100.0 |
|
2 |
45.0 |
7.70 |
124.4 |
45.4 |
9.20 |
149.2 |
|
|
8 |
48.9 |
12.94 |
193.2 |
50.6 |
14.40 |
209.6 |
|
|
12 |
52.0 |
16.23 |
227.1 |
53.1 |
17.88 |
247.9 |
|
|
16 |
54.1 |
20.78 |
279.5 |
54.9 |
20.58 |
276.0 |
|
|
20 |
56.2 |
24.84 |
322.0 |
57.3 |
23.62 |
303.6 |
|
|
Months |
6 |
59.1 |
30.80 |
379.2 |
61.0 |
28.32 |
341.9 |
|
9 |
66.3 |
38.70 |
424.7 |
64.6 |
34.60 |
394.6 |
|
Source: Volcani & Eyal, 1954 | |||||||
In Iraq, body
measurements of 12 single male, 16 single female, 12 twin male and 11 twin
female Awassi lambs have been recorded at birth and at 16,32 and 48 weeks at
the Abu-Ghraib Experiment Station (Table 3-122). The growth rates were highest
during the suckling period and decreased with advancing age. Sex had no
significant effect on heart girth, height at withers or length of body. Single
or twin births had highly significant effects on heart girth and length of
body, and a significant effect on height at withers at birth. With growing age
these effects gradually decreased until they ceased completely (Juma et al., 1969).
The effects of
year of birth, sex of lamb, type of birth, age of dam and month of birth on the
development of Awassi lambs at birth, weaning and yearling age have been
studied by Kazzal (1973) at the Hammām Al'Alii Agricultural Experiment Station in Iraq for three years
(Table 3-123) (for numbers of lambs see Table 3-70).
At birth single
lambs were larger in all body dimensions than twin lambs. The effect of the age
of the dam on height at withers and length of body, but not on other body
measurements, was significant.
At weaning, body dimensions were
significantly influenced by the year of birth. Differences in mean measurements
at weaning reflect yearly differences in nutrition, climate and other
environmental factors. Height at withers, height and width at hip bones, and
heart girth were greater in male than in female lambs. The effect of the month
of birth on length of body, width of chest and at hip bones, and on heart girth
was highly significant. Although the age of the dam did not significantly
affect any of the body measurements of lambs taken, there was a general
tendency for several measurements to increase with increases in the age of the
dam up to 5½ years.
At the age of ä year differences in body
measurements attributable to the year of birth and sex of lamb were highly
significant. Male yearlings exceeded females by 4.46 cm in height at withers,
3.99 cm in height at hip bones, 1.98 cm in length of body, 1.53 cm in width of
chest, and 1.78 cm in both width at hip bones and heart girth. The type of
birth, the age of the dam and month of birth exerted less pronounced effects on
yearling body dimensions than at earlier ages. The type of birth had a
significant effect on heart girth and height at withers and hip bones, and the
month of birth on height at withers, length of body and heart girth. The age of
the dam had no significant influence on any of the yearling measurements
studied (Kazzal, 1973).
In an experiment
with 20 fat-tailed and 20 docked male Awassi lambs at the Abu-Ghraib Experiment
Station, Iraq, length of body, height at withers and heart girth were measured
at fortnightly or monthly intervals (Asker et al., 1964).
The lambs were weaned at the age of four months, received hay from five to ten
months of age, and a ration of concentrates for fattening for another two
months. At the age of nine months the animals were shorn (see also Table 5-18).
At all stages the
docked lambs were inferior to the undocked ones in the three body dimensions
measured. The highest rate of growth was in heart girth, and the lowest in
height at withers. The general drop in measurements at the ninth month was due
to shearing (Fig. 3-18).
Table 3-124 gives
the correlation coefficients established between body weight and heart girth
and height at withers at different ages.
|
TABLE 3-119. Mean body measurements of male Awassi
sheep at different ages (cm) |
|||||||||
|
Measurement |
|
1-3 days |
4-10 days |
11-30 days |
2 months |
3 months |
4 months |
6 months |
Adult |
|
|
No.: |
8 |
18 |
20 |
15 |
11 |
16 |
18 |
9 |
|
Height at withers |
|
38.3 ±1.58 |
42.3 ±2.05 |
48.2 ±1.87 |
52.9 ±1.96 |
56.6 ±2.87 |
60.8 ±3.80 |
65.5 ±2.85 |
85.4 ± 4.75 |
|
Height at hook bones |
|
39.9 ±2.10 |
43.6 ±1.88 |
50.1 ±1.89 |
54.9 ±2.13 |
58.8 ±3.16 |
64.8 ±3.29 |
68.9 ±3.43 |
86.8 ± 4.32 |
|
Length of body |
|
31.0 ±1.69 |
34.3 ±3.24 |
42.1 ±4.78 |
50.5 ±3.74 |
54.7 ±4.03 |
58.6 ±3.59 |
61.9 ±4.57 |
87.3 ± 6.19 |
|
Length of foreleg |
|
26.8 ±1.04 |
28.5 ±1.25 |
32.4 ±1.49 |
34.5 ±1.51 |
37.2 ±2.18 |
38.8 ±1.22 |
40.9 ±2.28 |
50.3 ± 3.57 |
|
Length of hindleg |
|
29.6 ±1.50 |
31.1 ±1.39 |
34.7 ±1.81 |
37.8 ±2.14 |
40.6 ±1.96 |
42.7 ±1.08 |
44.1 ±3.64 |
53.4 ± 2.92 |
|
Width of chest |
|
11.4 ±1.06 |
12.7 ±1.52 |
15.0 ±1.25 |
16.5 ±1.30 |
17.9 ±2.26 |
20.6 ±1.09 |
22.9 ±1.45 |
29.4 ± 3.13 |
|
Width at hip bones |
|
10.7 ±0.46 |
12.4 ±1.29 |
15.9 ±1.51 |
17.7 ±1.63 |
18.4 ±2.37 |
20.7 ±1.08 |
23.6 ±1.38 |
30.4 ± 2.83 |
|
Heart girth |
|
38.5 ±1.60 |
42.7 ±3.63 |
52.0 ±2.95 |
57.7 ±3.59 |
65.9 ±3.51 |
75.0 ±1.63 |
83.2 ±6.18 |
113.0 ± 4.55 |
|
Shank girth |
|
5.9 ±0.50 |
6.8 ±0.57 |
7.6 ±0.66 |
7.6 ±0.56 |
8.1 ±0.58 |
8.6 ±0.43 |
9.3 ±0.69 |
10.9 ± 0.73 |
|
Length of tail (without wool) |
|
12.3 ±2.37 |
13.3 ±2.05 |
17.3 ±3.26 |
17.5 ±4.19 |
18.6 ±4.84 |
25.2 ±2.34 |
30.1 ±4.41 |
33.8 ± 4.99 |
|
Greatest width of fat tail |
|
6.8 ±1.98 |
8.6 ±2.76 |
16.2 ±3.04 |
17.3 ±3.35 |
20.6 ±4.65 |
26.4 ±2.87 |
30.2 ±4.15 |
35.9 ± 5.06 |
|
Length of head |
|
15.6 ±1.35 |
16.1 ±1.54 |
18.9 ±1.59 |
19.8 ±1.22 |
20.8 ±1.94 |
23.4 ±2.16 |
24.9 ±1.69 |
33.1 ± 1.83 |
|
Interorbital width of head |
|
8.9 ±0.44 |
9.6 ±0.54 |
10.7 ±0.54 |
11.1 ±0.95 |
11.5 ±0.59 |
12.2 ±0.91 |
12.6 ±0.81 |
15.4 ± 1.24 |
|
Length of ear |
|
10.5 ±0.75 |
11.8 ±1.45 |
14.1 ±1.22 |
14.9 ±1.46 |
15.1 ±0.88 |
15.3 ±0.92 |
15.5 ±1.06 |
16.0 ±20.50 |
|
Greatest width of ear |
|
5.8 ±0.96 |
6.5 ±0.61 |
7.4 ±0.72 |
7.7 ±0.56 |
8.4 ±0.77 |
8.6 ±0.42 |
8.8 ±0.41 |
9.7 ± 0.91 |
|
Length of horn along curve |
|
0.5 ±0 |
1.3 ±0.88 |
2.7 ±1.48 |
4.2 ±1.83 |
8.7 ±1.83 |
12.6 ±2.16 |
19.8 ±6.70 |
57.6 ± 2.50 |
|
Basal girth of horn |
|
2.0 ±0 |
2.6 ±0.78 |
3.9 ±1.05 |
4.7 ±1.36 |
7.6 ±1.17 |
8.8 ±0.94 |
12.1 ±3.06 |
21.2 ± 3.96 |
|
TABLE 3-120. Mean body measurements of female Awassi
sheep at different ages (cm) |
|||||||||
|
Measurement |
|
1-3 days |
4-10 days |
11-30 days |
2 months |
3 months |
4 months |
6 months |
Adult |
|
|
No.: |
5 |
17 |
29 |
18 |
11 |
14 |
46 |
17 |
|
Height at withers |
|
36.4 ±1.52 |
38.9 ±2.16 |
44.6 ±2.41 |
51.6 ±2.28 |
55.6 ±1.69 |
59.7 ±2.40 |
65.5 ±2.85 |
73.7 ±4.50 |
|
Height at hook bones |
|
37.5 ±1.50 |
40.4 ±2.18 |
45.8 ±2.61 |
53.2 ±2.49 |
57.6 ±1.57 |
62.5 ±2.71 |
67.5 ±2.60 |
76.7 ±4.01 |
|
Length of body |
|
29.1 ±3.13 |
33.2 ±2.49 |
38.2 ±4.21 |
50.6 ±3.96 |
55.3 ±3.64 |
56.5 ±5.00 |
59.8 ±4.48 |
75.8 ±5.71 |
|
Length of foreleg |
|
25.2 ±1.30 |
26.4 ±1.50 |
29.8 ±1.58 |
34.0 ±2.03 |
37.8 ±1.54 |
38.1 ±1.66 |
40.3 ±2.06 |
44.6 ±2.85 |
|
Length of hindleg |
|
26.6 ±1.14 |
28.2 ±1.56 |
31.9 ±2.27 |
36.7 ±2.00 |
40.1 ±1.70 |
40.8 ±2.01 |
43.4 ±2.45 |
48.9 ±4.64 |
|
Width of chest |
|
10.5 ±0.50 |
11.4 ±1.28 |
14.1 ±1.55 |
17.3 ±2.24 |
19.8 ±0.75 |
20.7 ±2.27 |
21.0 ±2.58 |
26.2 ±2.35 |
|
Width at hip bones |
|
9.8 ±1.04 |
11.4 ±1.46 |
14.7 ±1.72 |
18.4 ±1.88 |
20.5 ±3.48 |
20.6 ±2.16 |
21.5 ±2.72 |
28.1 ±2.66 |
|
Heart girth |
|
36.0 ±1.41 |
38.9 ±2.41 |
47.8 ±3.86 |
57.4 ±4.90 |
71.6 ±4.59 |
72.3 ±4.36 |
78.2 ±4.55 |
100.2 ±5.03 |
|
Shank girth |
|
6.0 ±0.35 |
6.4 ±0.53 |
7.1 ±0.48 |
7.5 ±0.47 |
7.9 ±0.77 |
8.2 ±0.60 |
8.5 ±0.62 |
9.4 ±1.00 |
|
Length of tail (without wool) |
|
12.6 ±1.91 |
13.8 ±2.95 |
16.0 ±3.22 |
18.6 ±3.54 |
22.4 ±2.34 |
24.4 ±3.78 |
27.4 ±3.33 |
30.7 ±4.31 |
|
Greatest width of fat tail |
|
4.9 ±1.14 |
8.1 ±1.82 |
13.5 ±3.20 |
18.6 ±3.29 |
20.4 ±3.14 |
22.3 ±2.05 |
25.8 ±3.06 |
30.6 ±3.95 |
|
Length of head |
|
14.2 ±1.09 |
15.0 ±0.94 |
17.7 ±1.70 |
20.2 ±1.83 |
22.9 ±0.70 |
23.5 ±1.40 |
25.2 ±1.85 |
29.2 ±1.35 |
|
Interorbital width of head |
|
8.8 ±0.68 |
9.2 ±0.45 |
9.9 ±0.72 |
10.9 ±0.64 |
12.0 ±0.89 |
12.2 ±0.70 |
12.3 ±0.63 |
13.7 ±1.05 |
|
Length of ear |
|
9.5 ±0.71 |
10.9 ±1.38 |
13.1 ±1.23 |
14.4 ±1.14 |
16.1 ±1.23 |
16.4 ±1.18 |
16.8 ±1.70 |
18.5 ±2.10 |
|
Greatest width of ear |
|
5.8 ±0.27 |
6.2 ±0.68 |
7.2 ±0.79 |
7.6 ±0.45 |
8.4 ±0.84 |
8.5 ±0.47 |
8.8 ±0.83 |
9.4 ±0.75 |
|
Length of horn along curve |
|
— |
— |
0.8 ±0.35 |
1.3 ±0.87 |
1.3 ±0.49 |
1.9 ±1.46 |
4.5 ±3.23 |
4.6 ±2.42 |
|
TABLE 3-121. Mean
body measurements of male ana
female Awassi sheep at different ages (7o of
measurements of new-born lambs) |
||||||||||||||||
|
Measurement |
1 3 days |
4-10 days |
11-30 days |
2 months |
3 months |
4 months |
6 months |
Adult |
||||||||
|
♂ |
♀ |
♂ |
♀ |
♂ |
♀ |
♂ |
♀ |
♂ |
♀ |
♂ |
♀ |
♂ |
♀ |
♂ |
♀ |
|
|
Height at withers |
100.0 |
100.0 |
110.4 |
106.9 |
125.8 |
122.5 |
138.1 |
141.8 |
147.8 |
152.7 |
158.7 |
164.0 |
171.0 |
179.9 |
223.0 |
202.5 |
|
Height at hook bones |
100.0 |
100.0 |
109.3 |
107.7 |
125.6 |
122.1 |
137.6 |
141.9 |
147.4 |
153.6 |
162.4 |
166.7 |
172.7 |
180.0 |
217.5 |
204.5 |
|
Length of body |
100.0 |
100.0 |
110.6 |
114.1 |
135.8 |
131.3 |
162.9 |
173.9 |
176.5 |
190.0 |
189.0 |
194.2 |
199.7 |
205.5 |
281.6 |
260.5 |
|
Length of foreleg |
100.0 |
100.0 |
106.3 |
104.8 |
120.9 |
118.3 |
128.7 |
134.9 |
138.8 |
150.0 |
144.8 |
151.2 |
152.6 |
159.9 |
187.7 |
177.0 |
|
Length of hindleg |
100.0 |
100.0 |
105.1 |
106.0 |
117.2 |
119.9 |
127.7 |
138.0 |
137.2 |
150.8 |
144.3 |
153.4 |
149.0 |
163.2 |
180.4 |
183.8 |
|
Width of chest |
100.0 |
100.0 |
111.4 |
108.6 |
131.6 |
134.3 |
144.7 |
164.8 |
157.0 |
188.6 |
180.7 |
197.1 |
200.9 |
200.0 |
257.9 |
249.5 |
|
Width at hip bones |
100.0 |
100.0 |
115.9 |
116.3 |
148.6 |
150.0 |
165.4 |
187.8 |
172.0 |
209.2 |
193.5 |
210.2 |
220.6 |
219.4 |
284.1 |
286.7 |
|
Heart girth |
100.0 |
100.0 |
110.9 |
108.1 |
135.1 |
132.5 |
149.9 |
159.4 |
171.2 |
198.9 |
194.8 |
200.8 |
216.1 |
217.2 |
293.5 |
278.3 |
|
Shank girth |
100.0 |
100.0 |
115.5 |
106.7 |
128.8 |
118.3 |
128.8 |
125.0 |
137.3 |
131.7 |
145.8 |
136.7 |
157.6 |
141.7 |
184.7 |
156.7 |
|
Length of tail (without wool) |
100.0 |
100.0 |
108.1 |
109.5 |
140.7 |
127.0 |
142.3 |
147.6 |
151.2 |
177.8 |
204.9 |
193.7 |
244.7 |
217.5 |
274.8 |
243.7 |
|
Greatest width of fat tail |
100.0 |
100.0 |
126.5 |
165.3 |
238.2 |
275.5 |
254.4 |
379.6 |
302.9 |
416.3 |
388.2 |
455.1 |
444.1 |
526.5 |
527.9 |
624.5 |
|
Length of head |
100.0 |
100.0 |
103.2 |
105.6 |
121.2 |
124.6 |
127.7 |
142.3 |
133.3 |
161.3 |
151.0 |
165.5 |
159.6 |
177.5 |
212.2 |
205.6 |
|
Interorbital width of head |
100.0 |
100.0 |
107.9 |
104.5 |
120.2 |
112.5 |
124.7 |
123.9 |
129.2 |
136.4 |
137.1 |
138.6 |
141.6 |
139.8 |
173.0 |
155.7 |
|
Length of ear |
100.0 |
100.0 |
112.4 |
114.7 |
134.3 |
137.9 |
141.9 |
151.6 |
143.8 |
169.5 |
145.7 |
172.6 |
147.6 |
176.8 |
152.4 |
194.5 |
|
Greatest width of ear |
100.0 |
100.0 |
112.1 |
106.9 |
127.6 |
122.4 |
132.8 |
131.0 |
144.8 |
144.8 |
148.3 |
146.6 |
151.7 |
151.7 |
167.2 |
162.1 |
|
Length of horn along curve |
100.0 |
100.0 |
260.0 |
|
540.0 |
|
840.0 |
|
1 740.0 |
|
2 520.0 |
|
3 960.0 |
|
11 520.0 |
|
|
Basal girth of horn |
100.0 |
100.0 |
130.0 |
|
195.0 |
|
235.0 |
|
380.0 |
|
440.0 |
|
605.0 |
|
1 060.0 |
|
|
TABLE 3-122. Mean body measurements of Awassi
lambs at different ages in Iraq (cm and % of measurements at birth = 100) |
|||||||||
|
Sex and type of birth |
Measurement |
Birth |
16 weeks |
32 weeks |
48 weeks |
||||
|
cm |
% |
cm |
% |
cm |
% |
cm |
% |
||
|
Single male |
Heart girth |
38.4 |
100 |
67.6 |
176 |
77.7 |
202 |
87.8 |
229 |
|
Height at withers |
40.1 |
100 |
60.6 |
151 |
67.2 |
168 |
72.4 |
181 |
|
|
Length of body |
27.5 |
100 |
54.7 |
199 |
65.4 |
238 |
70.4 |
256 |
|
|
Single female |
Heart girth |
37.9 |
100 |
67.9 |
179 |
74.0 |
195 |
88.9 |
235 |
|
Height at withers |
39.1 |
100 |
59.8 |
153 |
64.4 |
165 |
70.2 |
180 |
|
|
Length of body |
27.1 |
100 |
54.7 |
202 |
61.4 |
227 |
67.3 |
248 |
|
|
Twin male |
Hearth girth |
36.0 |
100 |
63.2 |
176 |
72.5 |
201 |
84.0 |
233 |
|
Height at withers |
36.9 |
100 |
56.3 |
153 |
64.4 |
175 |
71.0 |
192 |
|
|
Length of body |
24.9 |
100 |
51.4 |
206 |
61.5 |
247 |
68.3 |
274 |
|
|
Twin female |
Heart girth |
35.7 |
100 |
62.3 |
175 |
70.1 |
196 |
86.0 |
241 |
|
Height at withers |
37.3 |
100 |
55.8 |
150 |
62.3 |
167 |
68.5 |
184 |
|
|
Length of body |
25.1 |
100 |
49.9 |
199 |
59.7 |
238 |
66.7 |
266 |
|
|
Source: Juma |
et al., 1969 |
|
|
|
|
|
|
|
|
TABLE 3-123. Body measurements of Awassi lambs at birth, weaning
and yearling age in Iraq (least
squares means) (cm and % of measurements at birth = 100) |
Effect of year of birth |
||||||
|
Measurement |
Age: |
Birth |
Weaning |
1 year |
|||
|
cm |
% |
cm |
% |
cm |
% |
||
|
Height at
withers |
1966 |
37.9 |
100 |
54.7 |
144 |
63.8 |
168 |
|
1967 |
34.9 |
100 |
51.7 |
148 |
63.3 |
181 |
|
|
1970 |
30.6 |
100 |
48.8 |
159 |
58.3 |
191 |
|
|
Height at hip
bones |
Average |
34.4 |
100 |
51.7 |
150 |
61.8 |
180 |
|
1966 |
38.6 |
100 |
55.7 |
144 |
65.1 |
169 |
|
|
1967 |
35.8 |
100 |
52.8 |
147 |
64.3 |
180 |
|
|
1970 |
29.5 |
100 |
47.8 |
162 |
58.6 |
199 |
|
|
Length of
body |
Average |
34.6 |
100 |
52.1 |
151 |
62.7 |
181 |
|
1966 |
30.2 |
100 |
53.9 |
178 |
66.6 |
221 |
|
|
1967 |
30.6 |
100 |
49.5 |
162 |
65.3 |
213 |
|
|
1970 |
30.2 |
100 |
48.4 |
160 |
61.1 |
202 |
|
|
Width of
chest |
Average |
30.3 |
100 |
50.6 |
167 |
64.3 |
212 |
|
1966 |
8.4 |
100 |
13.4 |
160 |
19.1 |
227 |
|
|
1967 |
7.6 |
100 |
13.7 |
180 |
21.6 |
284 |
|
|
1970 |
6.2 |
100 |
12.1 |
195 |
16.8 |
271 |
|
|
Width at hip
bones |
Average |
7.4 |
100 |
13.1 |
177 |
19.2 |
259 |
|
1966 |
9.5 |
100 |
14.3 |
151 |
21.8 |
229 |
|
|
1967 |
8.8 |
100 |
15.8 |
180 |
24.8 |
282 |
|
|
1970 |
7.1 |
100 |
13.7 |
193 |
20.9 |
294 |
|
|
Heart girth |
Average |
8.4 |
100 |
14.6 |
174 |
22.5 |
268 |
|
1966 |
39.9 |
100 |
68.3 |
171 |
89.8 |
225 |
|
|
1967 |
40.6 |
100 |
59.9 |
148 |
87.2 |
215 |
|
|
1970 |
38.1 |
100 |
61.0 |
160 |
84.6 |
222 |
|
|
|
Average |
39.5 |
100 |
63.1 |
160 |
87.2 |
221 |
|
Effect of sex of lamb |
|||||||
|
Height at
withers |
Male |
34.7 |
100 |
52.5 |
151 |
64.0 |
184 |
|
Female |
34.2 |
100 |
50.9 |
149 |
59.6 |
174 |
|
|
Height at hip
bones |
Male |
24.9 |
100 |
52.9 |
152 |
64.6 |
185 |
|
Female |
34.3 |
100 |
51.3 |
150 |
60.7 |
177 |
|
|
Length of
body |
Male |
30.5 |
100 |
50.8 |
167 |
65.3 |
214 |
|
Female |
30.2 |
100 |
50.4 |
167 |
63.7 |
210 |
|
|
Width of
chest |
Male |
7.5 |
100 |
13.1 |
175 |
19.9 |
265 |
|
Female |
7.3 |
100 |
13.0 |
178 |
18.4 |
252 |
|
|
Width at hip
bones |
Male |
8.6 |
100 |
14.7 |
171 |
23.4 |
272 |
|
Female |
8.4 |
100 |
14.5 |
173 |
21.6 |
257 |
|
|
Heart girth |
Male |
39.8 |
100 |
63.6 |
160 |
88.1 |
221 |
|
Female |
39.2 |
100 |
62.5 |
159 |
86.3 |
220 |
|
|
Effect of type of birth |
|||||||
|
Height at
withers |
Single |
35.3 |
100 |
53.3 |
151 |
63.3 |
179 |
|
Twin |
33.6 |
100 |
50.2 |
149 |
60.3 |
179 |
|
|
Height at hip
bones |
Single |
35.6 |
100 |
53.4 |
150 |
64.1 |
180 |
|
Twin |
33.7 |
100 |
50.8 |
151 |
61.2 |
182 |
|
|
Length of
body |
Single |
31.1 |
100 |
51.2 |
165 |
63.9 |
205 |
|
Twin |
29.6 |
100 |
49.9 |
169 |
64.8 |
219 |
|
|
Width of
chest |
Single |
7.7 |
100 |
13.5 |
175 |
19.5 |
253 |
|
Twin |
7.1 |
100 |
12.7 |
179 |
18.8 |
265 |
|
|
Width of
chest |
Single |
8.7 |
100 |
15.0 |
172 |
22.8 |
262 |
|
Twin |
8.2 |
100 |
14.3 |
174 |
22.2 |
271 |
|
|
Heart girth |
Single |
40.4 |
100 |
64.7 |
160 |
89.5 |
222 |
|
Twin |
38.6 |
100 |
61.4 |
159 |
84.9 |
220 |
|
|
Measurement |
Age: |
Birth |
Weaning |
1 year |
|||
|
cm |
% |
cm |
% |
cm |
% |
||
|
Effect
of age of dam (years) |
|||||||
|
Height at withers |
1½ |
34.1 |
100 |
51.6 |
151 |
62.7 |
184 |
|
2½ |
33.7 |
100 |
50.9 |
151 |
60.6 |
180 |
|
|
3½ |
34.2 |
100 |
51.7 |
151 |
62.4 |
182 |
|
|
4½ |
34.4 |
100 |
51.7 |
150 |
62.2 |
181 |
|
|
5½ |
34.9 |
100 |
52.2 |
150 |
61.8 |
177 |
|
|
6½ |
35.1 |
100 |
51.8 |
148 |
61.7 |
176 |
|
|
7½ |
34.7 |
100 |
52.2 |
150 |
60.3 |
174 |
|
|
Height at hip bones |
1½ |
34.6 |
100 |
51.4 |
149 |
64.3 |
186 |
|
2½ |
33.9 |
100 |
51.8 |
153 |
62.0 |
183 |
|
|
3½ |
34.5 |
100 |
51.9 |
150 |
63.2 |
183 |
|
|
4½ |
34.5 |
100 |
52.1 |
151 |
61.7 |
179 |
|
|
5½ |
34.9 |
100 |
52.4 |
150 |
63.4 |
182 |
|
|
6½ |
35.0 |
100 |
52.1 |
149 |
62.4 |
178 |
|
|
7½ |
35.0 |
100 |
52.9 |
151 |
61.5 |
176 |
|
|
Length of body |
1½ |
29.7 |
100 |
50.1 |
169 |
65.4 |
220 |
|
2½ |
30.5 |
100 |
50.4 |
165 |
64.6 |
212 |
|
|
3½ |
29.7 |
100 |
50.3 |
169 |
64.2 |
216 |
|
|
4½ |
31.1 |
100 |
50.8 |
163 |
64.8 |
208 |
|
|
5½ |
30.6 |
100 |
50.8 |
166 |
65.0 |
212 |
|
|
6½ |
30.6 |
100 |
51.0 |
167 |
64.1 |
209 |
|
|
7½ |
30.1 |
100 |
50.8 |
169 |
62.4 |
207 |
|
|
Width of chest |
1½ |
7.3 |
100 |
13.0 |
178 |
18.4 |
252 |
|
2½ |
7.3 |
100 |
13.0 |
178 |
19.2 |
263 |
|
|
3½ |
7.4 |
100 |
12.9 |
174 |
19.1 |
258 |
|
|
4½ |
7.4 |
100 |
13.1 |
177 |
19.2 |
259 |
|
|
5½ |
7.4 |
100 |
13.3 |
180 |
19.6 |
265 |
|
|
6½ |
7.5 |
100 |
13.0 |
173 |
19.4 |
259 |
|
|
7½ |
7.3 |
100 |
13.0 |
178 |
19.1 |
262 |
|
|
Width at hip bones |
1½ |
8.6 |
100 |
14.8 |
172 |
22.5 |
262 |
|
2½ |
8.3 |
100 |
14.5 |
175 |
22.2 |
267 |
|
|
3½ |
8.5 |
100 |
14.4 |
169 |
22.2 |
261 |
|
|
4½ |
8.5 |
100 |
14.5 |
171 |
22.8 |
268 |
|
|
5½ |
8.5 |
100 |
14.8 |
174 |
22.7 |
267 |
|
|
6½ |
8.6 |
100 |
14.6 |
170 |
22.6 |
263 |
|
|
7½ |
8.3 |
100 |
14.5 |
175 |
22.5 |
271 |
|
|
Heart girth |
1½ |
38.9 |
100 |
62.7 |
161 |
86.1 |
221 |
|
2½ |
39.7 |
100 |
62.4 |
157 |
86.4 |
218 |
|
|
3½ |
38.9 |
100 |
63.0 |
162 |
87.0 |
224 |
|
|
4½ |
40.2 |
100 |
63.1 |
157 |
88.9 |
221 |
|
|
5½ |
40.0 |
100 |
63.3 |
158 |
87.3 |
218 |
|
|
6½ |
39.7 |
100 |
63.2 |
159 |
87.9 |
221 |
|
|
7½ |
39.6 |
100 |
63.8 |
161 |
86.8 |
219 |
|
|
Effect of month of birth |
|||||||
|
Height at withers |
Nov. |
35.9 |
100 |
51.5 |
143 |
63.8 |
178 |
|
Dec. |
33.8 |
100 |
52.1 |
154 |
63.6 |
188 |
|
|
Jan. |
34.3 |
100 |
53.1 |
155 |
61.6 |
180 |
|
|
Feb. |
35.6 |
100 |
51.0 |
143 |
58.5 |
164 |
|
|
Mar. |
32.6 |
100 |
50.8 |
156 |
61.5 |
189 |
|
|
Height at hip bones |
Nov. |
36.3 |
100 |
52.1 |
144 |
65.0 |
179 |
|
Dec. |
33.9 |
100 |
52.4 |
155 |
64.0 |
189 |
|
|
Jan. |
34.5 |
100 |
53.1 |
154 |
63.0 |
183 |
|
|
Feb. |
35.5 |
100 |
51.6 |
145 |
58.1 |
164 |
|
|
Mar. |
33.0 |
100 |
51.3 |
155 |
63.2 |
192 |
|
|
Measurement |
Age: |
Birth |
Weaning |
1
year |
|||
|
cm |
% |
cm |
% |
cm |
% |
||
|
Length of body |
Nov. |
30.0 |
100 |
52.6 |
175 |
66.4 |
221 |
|
Dec. |
30.3 |
100 |
53.3 |
176 |
65.7 |
217 |
|
|
Jan. |
30.9 |
100 |
50.6 |
164 |
63.8 |
206 |
|
|
Feb. |
31.7 |
100 |
48.4 |
153 |
59.1 |
186 |
|
|
Mar. |
28.8 |
100 |
47.9 |
166 |
66.7 |
232 |
|
|
Width of chest |
Nov. |
7.9 |
100 |
13.7 |
173 |
19.3 |
244 |
|
Dec. |
7.7 |
100 |
13.3 |
173 |
18.8 |
244 |
|
|
Jan. |
7.4 |
100 |
13.3 |
180 |
18.9 |
255 |
|
|
Feb. |
7.0 |
100 |
12.6 |
180 |
20.1 |
287 |
|
|
Mar. |
6.9 |
100 |
12.5 |
181 |
18.6 |
270 |
|
|
Width at hip bones |
Nov. |
9.0 |
100 |
15.1 |
168 |
22.0 |
244 |
|
Dec. |
8.8 |
100 |
14.9 |
169 |
21.9 |
249 |
|
|
Jan. |
8.4 |
100 |
14.8 |
176 |
22.6 |
269 |
|
|
Feb. |
9.0 |
100 |
14.0 |
156 |
23.2 |
258 |
|
|
Mar. |
7.8 |
100 |
14.3 |
183 |
22.8 |
292 |
|
|
Heart girth |
Nov. |
38.7 |
100 |
64.9 |
168 |
90.2 |
233 |
|
Dec. |
39.4 |
100 |
65.1 |
165 |
89.7 |
228 |
|
|
Jan. |
41.0 |
100 |
63.8 |
156 |
81.3 |
198 |
|
|
Feb. |
41.3 |
100 |
61.9 |
150 |
81.4 |
197 |
|
|
Mar. |
37.2 |
100 |
59.6 |
160 |
93.4 |
251 |
|
Figure 3-18. Growth rates of length of body, height at withers, and heart girth in undocked male Awassi lambs in Iraq. (Source: Asker et al., 1964)
|
TABLE 3-124. Correlation coefficients between body weight and (A) heart girth and
(B) height at withers |
||||
|
Age
(months) |
Undocked |
Docked |
Average |
|
|
A |
4 |
0.598 |
0.888 |
0.743 |
|
8 |
0.627 |
0.727 |
0.677 |
|
|
12 |
0.605 |
0.881 |
0.743 |
|
|
B |
4 |
0.756 |
0.831 |
0.794 |
|
8 |
0.578 |
0.452 |
0.515 |
|
|
12 |
0.611 |
0.779 |
0.695 |
|
|
Source: Asker et al., 1964 |
||||
