Abortions
Preweaning mortality
Mortality after weaning
Offtake
Abortions in goats totalled 12.6% of all births while in sheep the corresponding figure was 5.1%.
The unadjusted mean preweaning mortality (to 150 days of age) was 34.4% in goats and 23.4% in sheep. In goats about 30% of all preweaning deaths (other than abortions) were stillbirths or occurred on the first day of life and a further 15% of kids died during the first week. In sheep some 17% of preweaning deaths were either stillbirths or first-day mortalities and a further 10% of deaths took place during the first 7 days. In goats, 66% of all deaths recorded during the study occurred before weaning while in sheep only 46% of deaths took place during that period.
The mean squares from the analysis of variance for preweaning mortality are given in Table 50. The main sources of variation influencing this parameter were the system, the season of birth, parity and flock in the millet subsystem. In goats, the year of birth had a highly significant effect and the sex of the kid also influenced the level of mortality. In sheep, the type of birth exerted a significant effect on the death rate.
Least-squares estimates of mortality are laid out in Table 51. For both goats and sheep there were more deaths in the millet than in the rice subsystem. In both species, young born in the cold dry season had a greater chance of dying than those born at other times of the year, the next highest mortality rate being suffered by young born during the hot dry season. Lowest death risk was met by young born during the rainy arid post-rains seasons. In goats there was an almost linear reduction in the mortality rate from 1978 to 1983. The trend for sheep was similar although the effect of year of birth on mortality in this species was not significant. More young of primiparous females died than of multiparous dams although only in goats was this reduction significant between the second and older parities. Sex and type of birth resulted in the expected trend in mortality, with more males than females and more offspring of multiple than of single births dying.
Table 50. Analysis of variance of preweaning mortality in goats and sheep in central Mali.
|
Source of variation |
|
Goats |
|
Sheep |
|
d.f. |
MS |
d.f. |
MS |
|
|
System |
1 |
1.04* |
1 |
0.95* |
|
Season of birth |
3 |
0.72* |
3 |
0.52* |
|
Year of birth |
5 |
2.46*** |
5 |
0.27 |
|
Parity |
4 |
3.15*** |
4 |
1.35*** |
|
Sex |
1 |
0.85* |
1 |
0.00 |
|
Type of birth |
1 |
0.41 |
1 |
1.06* |
|
Flock/millet |
13 |
0.91*** |
14 |
0.58*** |
|
Flock/rice |
5 |
0.30 |
16 |
0.27 |
|
Error |
2 001 |
0.21 |
1517 |
0.17 |
*** P<0.001; *P<0.05.
Table 51. Least-squares means for preweaning mortality (%) in goats and sheep in central Mali.
|
Variable
|
Goats |
Sheep |
|||
|
n |
|
n |
|
||
|
Overall |
2 035 |
35.0 |
1 563 |
28.0 |
|
|
System |
|||||
|
|
Millet |
1 603 |
38.6a |
1 067 |
32.1a |
|
|
Rice |
432 |
31.3b |
496 |
23.9b |
|
Season |
|||||
|
|
Cold dry |
378 |
39.5a |
322 |
32.9a |
|
|
Hot dry |
651 |
36.9ab |
518 |
28.1ab |
|
|
Rains |
369 |
32.5bc |
376 |
23.0b |
|
|
Post-rains |
637 |
30.9c |
347 |
27.9ab |
|
Year |
|||||
|
|
1978 |
158 |
51.5a |
178 |
34.4 |
|
|
1979 |
233 |
35.6bc |
189 |
27.8 |
|
|
1980 |
422 |
33.6bc |
321 |
27.5 |
|
|
1981 |
456 |
38.7b |
291 |
28.0 |
|
|
1982 |
411 |
31.2c |
285 |
27.6 |
|
|
1983 |
355 |
19.1d |
299 |
22.6 |
|
Parity |
|||||
|
|
1 |
429 |
47.9a |
387 |
38.6a |
|
|
2 |
307 |
38.8b |
299 |
22.7b |
|
|
3 |
258 |
31.4bc |
222 |
24.2b |
|
|
4 |
168 |
30.7bc |
150 |
28.3b |
|
|
³ 5 |
873 |
26.1c |
512 |
26.2b |
|
Sex |
|||||
|
|
Female |
998 |
32.9a |
800 |
27.9 |
|
|
Male |
1 037 |
37.0b |
763 |
28.1 |
|
Type of birth |
|||||
|
|
Single |
1 375 |
33.3 |
1 432 |
23.0a |
|
|
Multiple |
660 |
36.6 |
131 |
33.0b |
Within variable groups, means followed by different letters differ significantly (P<0.05). Variable groups without any letters did not show a significant difference in the analysis of variance.
Mortality in the period between weaning and 1 year of age amounted to only about 5% (i.e. almost 10% on a yearly basis) in both goats and sheep. The death rate after 1 year was higher in sheep than in goats, such that at 4 years of age only 30% of sheep born were still alive while 38% of goats survived to 4 years. For the calculation of these last two figures animals removed for slaughter or sale were obviously excluded from the analysis.
The mean annual mortality rate over 1 year of age was about 12.7% in goats, being somewhat higher in sheep. The trend observed in preweaning mortality rate was maintained in adult life: a greater percentage of animals died in the millet than in the rice subsystem and the death rate was higher in males than in females.
Slightly more than 17% of goat deaths were due to animals teeing 'lost' or taken by predators mainly dogs - and almost 10% of deaths in sheep were from these causes.
As for cattle, offtake was calculated on an annual basis as sales plus slaughter (for social purposes or in extremis) plus animals gifted out permanently. The data by species and system are provided in Table 52.
Table 52. Total annual offtake by system, sex of animals and species.
|
System and sex |
Offtake (%) |
||
|
Goats |
Sheep |
||
|
Millet subsystem |
13.8 |
23.5 |
|
|
|
Females |
9.0 |
14.7 |
|
|
Males |
38.7 |
45.5 |
|
Rice subsystem |
26.6 |
34.6 |
|
|
|
Females |
14.8 |
15.3 |
|
|
Males |
53.1 |
78.7 |
|
Overall |
19.3 |
26.8 |
|
For female goats approximately 30% of offtake was in the form of slaughter, about 8% in the form of gifts and 62% was through sales. For male goats about 39% of the animals were slaughtered, 6% were gifted and 55% were sold. Male goats were generally slaughtered before 1 year of age (63.5% of all slaughterings) while-a slightly lesser percentage (52.0) was sold before 1 year of age. Females were slaughtered (39.8% before 1 year old) and sold (32.5% before 1 year old) later than males. The overall average age at offtake was about 14 months, being about 15 days earlier in the rice than in the millet subsystem and about 100 days earlier for males than for females although castrated animals were kept on to older ages than entire males. Average weight at offtake was 20.7 kg, entire males weighing about 1 kg more than females with castrates being 6 and 8 kg heavier than males in the millet and rice subsystems respectively.
In sheep about 25% of female offtake was in the form of slaughter, only 2% as gifts and 73% as sales. For male sheep about 29% were slaughtered, 2% were gifted and 69% were sold. A similar percentage of male sheep (58.4) to that of male goats were slaughtered before 1 year old but a higher percentage (68.2) was sold before this age. As for goats, females were slaughtered (40.0% before 1 year old) and sold (44.5% before 1 year old) later than males. The overall average age at offtake was similar to that of goats at about 14 months but was very much later in the millet subsystem (16 months) than in the rice subsystem (12 months) and offtake of females in the former subsystem averaged at about 22 months compared with only 13 months in the latter. Average weight at offtake was 26.8 kg, being 24.8 kg in the millet zone (females 23.0 kg, males 24.7 kg, castrates 43.1 kg) and 29.8 kg in the rice zone (females 24.9 kg, males 31.5 kg, castrates 38.4 kg).
