Materials and methods
Results
Conclusions
References
A. G. Ageeb and J.K. Hillers
Abdel G. Ageeb is Livestock Genetics/Breeding Specialist with WSARP, PO Box 125, Khartoum North, the Sudan. J. K Hillers is Professor of the Department of Animal Science, Washington State University, Pullman, Washington 99164, USA. The authors would like to thank those officials of Gezira University who made the data available for this study and to acknowledge especially the assistance of USAID in covering the costs of computer analysis.The production and reproduction potentials of two local Sudanese breeds were studied. No significant differences (p>0.05) were detected between the two breeds in the traits studied except in age at first calving. Milk production was found to be better in quantity than in some African breeds as reported in the literature. However, the genetic potential of the Butana and Kenana may be appropriate for the improvement of nomadic herds in the Sudan and in other countries with similar environments.
Genetic improvement in daily milk yield is attainable, while improvements in calving interval and lactation length normally come from improvements in the environment. Programmes for improving the genetic level of Butana and Kenana need to be implemented to utilize their potential.
Most reports on dairy cattle production in the tropical and subtropical areas involved crossing indigenous with temperate breeds. Little attention has been paid to the genetic material of indigenous breeds themselves since they have been considered of low productivity. In many parts of Africa, cattle are owned by nomads or transhumants and lack of proper management, prevalence of disease and shortage of feed and water may suggest that these people should not own cattle involving crosses with temperate breeds. Improvement of their indigenous breeds may be a sounder policy. Therefore the general characteristics of production and reproduction of the native nomadic cattle merit an assessment similar to that made of cross-bred cattle on private and government farms.
Data were obtained from the Nisheishiba Farm of Gezira University, located in the central part of the Sudan, latitude 14°24' N, and longitude 33°29' E. The climatological data on rainfall and temperature are given in Figures 1 and 2. There are three distinct seasons in the year, based on rainfall and temperature: winter (November-February), dry summer (March-June) and wet summer (July-October).
Pregnant Kenana heifer - Génisse Kenana pleine - Novilla Kenana preñada
Cattle were maintained on irrigated pasture and fed green cut lubia (Dolichos lablab), Abu-70 (variety of sorghum), phillipesara (Phaseolus trilobus), and were also grazed on alfalfa. Concentrate feeds were fed to milking cows at milking (hand milking). Heifers, bulls and calves were also given concentrate feeds, particularly during the dry summer season. This feed was mainly composed of sorghum grains, wheat bran, wheat and sorghum straws.
In this study, information was used from records collected from 1966 to 1980. These records were subjected to a screening process to obtain a data set that would allow appropriate statistical interpretation. Calf records without birth dates were eliminated from the analysis.
Production and reproduction traits studied were: lactation milk yield (adjusted to 305 days), daily milk yield, age at first calving, calving interval and breeding efficiency. Breeding efficiency (BE), a measure of the deviation of reproductive performance from a specified level, was calculated by the method suggested by Wilcox, Pfau and Bartlett (1957):
where N = total number of parturitions and D = the number of days from the first to the last parturition.
Mixed model least-squares and maximum likelihood (Harvey, 1980) and General Linear Model (GLM) procedures were used to adjust for the effect of year, age, and season. Duncan's multiple range test (Kramer, 1957) and least significant difference (LSD) (Chew, 1977) were used for comparisons of means.
Milk yield
Milk yields of the two breeds in age groups, seasons and parities are given in Table 1. The average 305-day milk of the two breeds was 1 405 ±695 kg and factors having a significant effect on lactation milk yields were sire and year of calving. These findings agree with those of Alim (1962). Milk yields fluctuated over the years recorded (see Figure 3), resulting possibly from changes in management and levels of feed available. Daily milk yield was affected (p<0.05) by sire and year of calving, and lactation and daily milk yields were similar among age groups, seasons and parities (see Table 1).
Lactation length
The mean lactation length was 256 ±32 days and was affected (p<0.05) by sire, year of calving and parity number. Later parities had longer lactations. Lactation length was shorter than the 319 days reported by Danasoury and Bayoumi (1962) in first lactations in Butana cattle at a different location. The correlation coefficient between lactation length and lactation milk yield was 0.10 and 0.24 (p<0.05) for Butana and Kenana, respectively. Their low milk production, however, could be a result of their inherent shorter lactations. No significant differences were detected between the two breeds in daily milk yields and lactation lengths.
Butana first carver - Vache Butana, après son premier vêlage - Vaca Butana primeriza
Butana cow, lactating - Vache Butana, en lactation - Vaca Butana en lactación
Average annual rainfall, Gezira, 1970-84 - Précipitations moyennes annuelles, Gézireh, 1970-1984 - Precipitación anual media, Gezira, 1970-84
Maximum and minimum temperatures, Gezira, - Températures maximales et minimales, Gézireh, 1970-1980 - Temperaturas máximas y mínimas, Gezira, 1970-80
Average 305-day lactation milk yield of pure-bred at Nisheishiba Farm, 1966-80 - Production laitière moyenne pour une lactation de 305 jours, sujets de race pure, ferme de Nisheishiba, 1966-1980 - Producción media de leche en 305 días de lactación de las razas puras en la granja de Nisheishiba, 1966-80
Age at first calving
The mean age at first calving of the two breeds was 4.08 ±0.48 years. However, first calving of Butana cows was earlier (p<0.05) than Kenana (see Table 2). Danasoury and Bayoumi (1962) and Alim (1960) reported 3.6 and 3.2 years as the age at first calving for Butana and Kenana, respectively.
The climatic conditions of the particular year of birth as well as breed had an effect (p<0.05) on age at first calving. In the period of drought in the country, from 1971 to 1974, later ages at first calving were observed. This supports the concept that appropriate feeding and management in early life should lower the age at first calving (Mahadevan, 1953).
To examine the effect of age at first calving on first lactation milk yield, ages at first calving were grouped into three categories: three years and less, three to four years, and more than four years. First lactation milk yield was not affected (p>0.05) by age at first calving (see Table 2).
Calving interval
The maintenance of a lower calving interval is desirable in brood cows. The mean calving interval of the two breeds was 16.6 months, with Butane carving at 16.3 ±0.9 months and Kenana calving at 17.6 ±0.9 months but the difference between the two breeds was not significant (p>0.05) (see Table 1). Calving interval was affected (p<0.05) by season and year of calving, as well as breed x year interaction. Age (measured by lactation number), it is noted, had no effect at all on calving interval (p>0.05)
To study the effect of calving interval on subsequent lactation milk yield, calving intervals were grouped into four categories: categories 13 months and less, 13-17 months, 17-21 months, and more than 21 months. The effect of calving interval was significant (p<0.05) and a reduction in lactation milk yield was associated with longer calving intervals. It is of interest that Rodriguez (1976) reported similar results in his study of Holstein-Friesian cows in Nicaragua.
Breeding efficiency (BE)
The mean BE was estimated as 72.2 ±16.5 percent in the Butana and Kenana breeds while Bhatnagar and Sharma (1970) reported 84 percent BE for Sahiwal cows in India. The effect of BE on lactation milk yield was significant (p<0.05) and the correlation between BE and lactation milk yield was +0.22 (p<0.05). An average breeding efficiency of less than 100 percent indicates that 1 reproduction does not occur at a regular interval of 365 days in the herd studied. An improvement in BE, therefore, should increase lactation milk yield of the herd.
Birth weight
Birth weight is a result of maternal environment and genetic potential-for birth weight of the parents. The average birth weight of Butana calves was 26.4 ±2.1 kg while Kenana calves averaged 25.2 ±2.1 kg. The difference, therefore, was not significant (p>0.05) (see Table 3).
Sire, sex, and year of birth had significant (p<0.05) effects on birth weight of calves. Season and parity number, on the other hand, had no effects (p>0.05). Birth weight of male calves was heavier (p<0.05) than that of females.
Heritability and repeatability
Estimated by the paternal half-sib method, the heritabilities (h²) of daily milk yield and lactation length were estimated as 0.21 ±0.20 and 0.00, respectively (see Table 1). The between and within cows components of variance were utilized to estimate repeatabilities and were 0.22 and 0.07 for daily milk yield and lactation length, respectively.
Heritability and repeatability estimates of calving interval were 0.00 and 0.02, respectively, and those of birth weight were estimated as 0.83 ±0.24 and 0.18, respectively. No reason is evident to justify why the h² estimate was higher than the repeatability.
In this study, it is possible that the small sample size and the small number of progeny per sire might affect the magnitude of h² estimates. Of interest is the fact that Osman (1972) reported 0.49 h² for birth weight in Western cattle of the Sudan.
Summing up the findings of this analysis, it was found that milk production of the local Sudanese breeds was lower than yields reported from Taurus breeds in temperate climates but was, however, higher than production reported from most African breeds. Lactation milk yield of these breeds, for example, is higher than that of the following breeds: Boran in Kenya (545-1 814 kg/139-303 days; Payne, 1970); Arsi in Ethiopia (809 kg/272 days; Schaar, Brannang and Meskel, 1981); Ankole in Uganda (318-817 kg/212-239 days; Payne, 1970); Domiatta in Egypt (1 264 kg/305 days; Moneib, Afifi and Ibrahim, 1970); and Barraso in Guatemala (1 380 kg/225 days; FAO, 1985). McLaughlin (1955) reported that the genetic material possessed by the Sudanese cattle compared favourably with some of the milking breeds of India.
The reproductive performance of these cattle was poor by all measurements. This was probably due to poor management and breeding practices, low levels of feed, disease (particularly brucellosis) and heat detection problems. Genetic improvement in daily milk yield is, however, possible as indicated by the heritability estimate (0.21). The heritable fractions in both calving interval and lactation length were small. Dunbar and Henderson (1953) reported zero heritability of calving interval, which is similar to the results of this study.
1. Mean 305-day lactation milk yield (LM) and least-squares means of daily milk yield (DM), lactation length (LL) and calving interval (CI) in age groups, seasons and parities of breeds
Production moyenne d'une lactation de 305 jours, moyennes des moindres carrés de la production laitière journalière, durée de lactation et intervalle de vêlage en fonction des groupes d'âge, des saisons et de la parité
Producción media de leche en una lactación de 305 días (LM) y medias de los mínimos cuadrados de la producción diaria de leche (DM), la duración de la lactación (LL) y el intervalo entre partos (CI) por grupos de edades, estaciones y número de partos de las razas
|
Factor |
No. |
LM (kg) |
No. |
DM (kg) |
LL 1 2 (d) |
No. |
CI 2 (mo.) | |
|
Breed | ||||||||
|
|
Butana |
81 |
1 465 |
76 |
4.8 |
257 |
67 |
16.3 |
|
|
Kenana |
236 |
1 344 |
130 |
4.4 |
256 |
177 |
17.6 |
|
Age (yr) | ||||||||
|
|
3 and less |
2 |
1 881 |
2 |
5.8 |
332 |
- |
- |
|
|
3-4 |
15 |
1 323 |
17 |
4.4 |
297 |
2 |
17.5 |
|
|
4-5 |
13 |
1 316 |
31 |
3.7 |
246 |
13 |
16.2 |
|
|
5-6 |
12 |
1 389 |
31 |
4.2 |
194 |
29 |
16.3 |
|
|
6-7 |
14 |
1 385 |
30 |
4.7 |
244 |
32 |
16.4 |
|
|
7-9 |
17 |
1 359 |
49 |
4.4 |
213 |
54 |
17.2 |
|
|
9 |
8 |
1 451 |
46 |
5.1 |
272 |
64 |
17.9 |
|
Season | ||||||||
|
|
Winter |
20 |
1 366 |
71 |
4.4 |
245 |
72 |
15.9a |
|
|
Dry summer |
39 |
1 406 |
91 |
4.5 |
253 |
85 |
16.5ba |
|
|
Wet summer |
22 |
1 335 |
44 |
5.0 |
272 |
37 |
18.3b |
|
Parity | ||||||||
|
|
1 |
16 |
1 248 |
38 |
3.1 |
204a |
- |
- |
|
|
2 |
17 |
1 384 |
38 |
4.6 |
271ba |
- |
- |
|
|
3 |
15 |
1 432 |
34 |
4.8 |
261ba |
- |
- |
|
|
4 |
13 |
1 425 |
31 |
4.3 |
281b |
- |
- |
|
|
5 |
8 |
1 412 |
20 |
4.8 |
280cb |
- |
- |
|
|
6 |
7 |
1 307 |
18 |
4.1 |
292cb |
- |
- |
|
|
7 |
3 |
1 453 |
9 |
4.8 |
211cab |
- |
- |
|
|
8 |
2 |
1 616 |
9 |
5.1 |
220cab |
- |
- |
|
|
Heritability |
|
|
0.21 ±0.20 |
|
0.00 |
|
0.00 |
|
|
Repeatability |
|
|
0.22 |
|
0.07 |
|
0.02 |
1 Lactation length and daily milk yield have the same number of observations.
2 Means with no superscript in common are significantly different at p<0.05.
2. Effects of age at first calving (AC) and calving interval (CI) on lactation milk yield (LM) of breeds
Influence de l'âge au premier vêlage et de l'intervalle de vêlage sur la production de fait par lactation des races étudiées
Efectos de la edad del primer parto (AC) y el intervalo entre los partos (CI) sobre la producción de leche por lactación (LM) de las razas
|
Factor |
No. |
AC 1 (yr) |
No. |
CI (mo.) |
LM 1 (kg) | |
|
Breed | ||||||
|
|
Butana |
19 |
3.2a |
67 |
16.2 |
|
|
|
Kenana |
70 |
4.2b |
127 |
17.6 |
|
|
Age (yr) | ||||||
|
|
3 and less |
7 |
|
|
|
1 412 |
|
|
3-4 |
35 |
|
|
|
1 327 |
|
|
4 |
45 |
|
|
|
1 179 |
|
CI (mo.) | ||||||
|
|
13 and less |
113 |
|
|
|
1 501a |
|
|
13-17 |
80 |
|
|
|
1 367ba |
|
|
17-21 |
38 |
|
|
|
1 285ba |
|
|
21 |
40 |
|
|
|
1 131b |
1 Means with no superscript in common are significantly different at p<0.05.
3. Least-squares means of birth weight of calves of both breeds
Moyennes des moindres carrés du poids de naissance des veaux des deux races
Medias de los mínimos cuadrados del peso al nacer de los ternero de ambas razas
|
Factor |
No. |
Birth weight 1 (kg) | |
|
Breed | |||
|
|
Butana |
101 |
26.4 |
|
|
Kenana |
288 |
25.2 |
|
Sex | |||
|
|
Male |
213 |
26.7a |
|
|
Female |
176 |
25.0b |
|
Season | |||
|
|
Winter |
124 |
25.8 |
|
|
Dry summer |
161 |
25.7 |
|
|
Wet summer |
104 |
26.1 |
|
Parity | |||
|
|
1 |
84 |
24.6 |
|
|
2 |
88 |
25.3 |
|
|
3 |
77 |
26.5 |
|
|
4 |
54 |
26.1 |
|
|
5 |
33 |
25.2 |
|
|
6 |
23 |
25.3 |
|
|
7 |
13 |
26.4 |
|
|
8 |
10 |
26.9 |
|
|
9 |
7 |
26.5 |
|
|
Overall |
389 |
25.9 |
1 Means With no superscript in common are significantly different at p<0.05.
To conclude, improvement in calving interval and lactation length should result from improvement in husbandry by proper management, better feeding and greater disease control, whereas milk yield is susceptible to genetic selection.
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