Abstract
Résumé
Introduction
Materials and methods
Results and discussion
Conclusions
References
S.K. Karua and J.W. Banda
Bunda College of Agriculture
Box 219, Lilongwe, Malawi
Some Malawi local goats were mated to Saanen bucks and others to local bucks under the same management at the Bunda College farm. Gestation length, birthweights, weaning weight, weight gain per day and weights at one year were observed and compared.
The average gestation length of local dams sired by Saanen bucks (146.90±2.68 days) was not significantly different from that of dams sired by local bucks (147.76±3.44 days). Sex of kids and litter sizes did not affect gestation length and although younger dams and dams kidding in the hot wet season had shorter gestation lengths than older dams and those kidding in the cool dry and hot dry seasons, respectively, the differences were not statistically significant
With the exception of twin-born males, birthweights of Saanen crosses were significantly higher than local kids. Likewise, weaning weights and weights at one year were higher in the Saanen crosses than in the local kids. Weight gains per day were higher before weaning than after and were higher in Saanen crosses than in the local kids. Mortality was 22% in Saanen crosses and 21% in the local kids.
Des chèvres de race locale du Malawi ont été croisées avec des boucs Saanen ou de race locale à la ferme du Bunda College of Agriculture. La durée de la gestation, le poids des chevreaux à la naissance, au sevrage et à l'âge de 1 an et le gain journalier de poids ont été enregistrés et comparés.
La durée moyenne de la gestation des femelles saillies par des mâles Saanen (146,90±2,68 jours) n'était pas significativement différente de celle des femelles saillies par des boucs de race locale (147, 76±3,44 jours). Ni le sexe des chevreaux ni la taille de la portée n'avaient d'effet sur la durée de la gestation. Sans présenter des différences significatives, celle-ci était plus courte pour les chèvres plus jeunes et pour les naissances intervenant au cours de la saison chaude et humide par rapport à la saison fraîche et sèche ou à la saison chaude et sèche,
Exception faite des jumeaux mâles, le poids à la naissance des croisements de Saanen était significativement supérieur à celui des chevreaux de race locale. De même, les poids au sevrage et à l'âge de 1 an de ces croisements étaient significativement plus élevés que ceux des chevreaux de race locale. Le gain de poids journalier était plus élevé avant qu'après le sevrage et plus élevé chez les croisements de Saanen que chez les chevreaux de race locale. Le taux de mortalité des premiers était de 22% contre 21% pour les seconds.
The zebu cow has remained the major source of milk in rural areas of Malawi where 89% of the people live. Improved dairy cattle breeds are concentrated in areas surroUnding urban centres designated as Milk Shed Areas.
Figures on milk consumption in rural areas are not available. However, FAO (1986) reported that total milk production in Malawi was 40 million kg which gave an estimated per capita consumption of 5 kg. With a population which is increasing at 3.2% per annum but with about 0.95 ha of land per capita (Munthali, 1987), the likelihood of improving this per capita milk consumption is remote. The goat, due to its small size and hence lower feed and capital requirements, can supplement cattle as a source of milk specially for rural areas.
Keeping goats is already popular among the smallholder farmers in Malawi. A survey conducted by Banda and Phiri (1990) indicated that goat milk is not discriminated against and is actually preferred in some cases. However, milk production from local goats is low (Mwenefumbo and Phoya, 1982; Banda, 1989). As an effort to improve milk production from goats, crossbreeding Saanen bucks to Malawi local goats commenced on an experimental basis at Bunda College of Agriculture in 1988. SO far, observations have been on gestation length, birthweights, weaning weight and growth to one year.
Indigenous (local) Malawi does were mated randomly either to Saanen bucks or to local bucks at the Bunda College farm (latitude 14°35'S, longitude 33°50'E, 1200 m above sea level). The doe were herded on natural pastures together with a vasectomised buck. Any doe noticed on heat was separated and mated to a fertile buck. This provided an opportunity to record accurately the mating day, kidding day and calculate gestation length. Also recorded at kidding was kid weight, litter sizes and sex of kid. All male kids in both groups were castrated at two weeks of age. Age of the dams was determined using dentition (Wilson and Durkin, 1985).
All kids together with their dams were fed indoors on Star grass (Cynodon nlemfuensis) and Napier grass (Pennisetum purpureum) for the first one month. Thereafter they were herded on natural pastures together with the rest of the flock No supplementary feeding was done and the dams were not milked. Mortality was also recorded.
The data were analysed using Statistix 2.0 Program on the Unisys Computer available at Bunda College.
Gestation length
Effect of breed of sire on gestation length
The average gestation length of dams sired by Saanen bucks was not different from that of dams sired by local bucks (Table 1). Although previous data on gestation length of Malawi local goats are not available, that of Saanen has been reported to be 150 days (Peaker, 1978). This seems to indicate that the sire of the litter has no effect on gestation length. Overall gestation length was 147.17±2.58 days and agrees with reports by Wilson (1957) on the Mubende goat in Uganda (146 1/2 days).
Table 1. Gestation length (days) of local dams sired by Saanen and pure local bucks.
|
According to |
No. of kiddings |
Gestation length |
SE |
|
Overall |
74 |
147.17 |
2.58 |
|
Breed of sire: Saanen |
56 |
146.90 |
2.68 |
|
Local |
18 |
147.76 |
3.44 |
|
Age of dam 1 pair |
9 |
144.89 |
3.10 |
|
2 pairs (19-23 months) |
7 |
145.60 |
5.17 |
|
3 pairs (24-31 months) |
35 |
147.80 |
2.85 |
|
4 pairs (over 32 months) |
23 |
146.95 |
2.69 |
|
Litter size: Single birth |
62 |
147.14 |
2.86 |
|
Multiple births |
12 |
147.09 |
3.05 |
|
Sex of kid: Male |
38 |
146.94 |
2.79 |
|
Female |
36 |
147.34 |
2.79 |
|
Season of kidding: Cool dry season (May to Aug) |
19 |
147.00 |
2.38 |
|
Hot dry season (Sep to Nov) |
26 |
147.23 |
3.20 |
|
Hot wet season (Dee to Apr) |
29 |
146.46 |
2.92 |
Effect of age of dam and season of kidding on gestation length
Although dams that kidded in the wet season and were younger had shorter gestation lengths than the others, the observed differences were not statistically significant. However, results reported by Asdell (1929) seem to have shown significant age and seasonal differences.
Effect of litter size and sex of kid on gestation length
Gestation length in dams kidding single kids (147.14±2.86 days) was about the same as in dams kidding multiple kids (147.09±3.05 days). Similarly, the gestation length in those kidding male kids (146.94±2.7 days) were the same as those kidding female kids (147.34±2.98 days). The results therefore agree with Asdell (1929) that gestation length is not affected by litter size and sex of kid.
Birth and mortality of kids
With the exception of males born as twins, birthweights of Saanen crosses were significantly higher than those of pure local (Table 2). Birthweights of males were also higher than that of females in both groups. Mortality rates of kids were 22% in local kids and 21 % in Saanen crosses. It is difficult to suggest reasons for these mortality rates since postmortem examination of dead kids was not conducted.
Growth performance
As in birthweight, weaning weights and weights at 1 year (364 days) were significantly higher in the Saanen crosses than in pure locals in both male and female kids (Table 3). Weight gains per day were also higher in the Saanen crosses than in the pure locals both before and after weaning.
Unlike the Saanen crosses where males had higher weaning weights (12.80 ± 5.14 kg) and weight at one year (25.00±3.00 kg) than females (11.96±2.77 kg at weaning and 22.50±1.78 kg at one year), in the pure local kids, the females had higher weaning weight (8.33±0.7 kg) and weight at one year (16.16±1.55 kg) than males (7.60±1.53 kg at weaning and 14.99±1.66 kg at one year). Similarly, weight gains per day were higher in males (92.32 gm before and 48.41 gm after weaning) than in females (82.67 gm before 41.82 gm after weaning) in the Saanen crosses, but higher in females (56 gm before and 31 gm after weaning) than males (50 gm before and 29 gm after weaning) in pure local kids. This could be attributed to the effect of castration. However, similar results have been reported by Kasowanjete et al (1987) in the Malawi goats.
So far, these observations indicate that Saanen crosses are performing better than pure local kids (higher birthweights, weaning weights, weight gains per day and weight at one year) under the same management. However, this was at a research station and further investigations are planned for village conditions. Similar studies are planned for 3/4 and 1/4 Saanen under both station and village management before a firm recommendation is made.
Table 2. Birthweights of Saanen x Local (SL) and Pure Local (PL) at Bunda College farm (kg).
|
Breed |
|
Singles |
Twins |
||
|
M |
F |
M |
F |
||
|
Saanen x Local |
n |
24 |
26 |
6 |
4 |
|
x |
2.61±0.39a |
2.48±0.54a |
2.08±0.45 |
2.00±0.35a |
|
|
Pure x Local |
n |
16 |
23 |
11 |
7 |
|
x |
1.93±0.53b |
1.84±0.48b |
1.95±0.26 |
1.75±0.24b |
|
Means with different superscripts in each column differ significantly (P.
Table 3. Growth performance of Saanen x Local and Pure x Local goats at Bunda College Farm.
|
Breed |
n |
Weaning weight(X±sd) (112 days) |
Weight gain per day to wearing(g) |
Weight at (X±sd) 364 days |
Weight gain/day(gm) from weaning to 364 days | |
|
Saanen x Local M |
17 |
12.80±5.14 |
92.32 |
25.00±3.00 |
48.41 | |
|
|
F |
18 |
11.96±2.77 |
82.67 |
22.50±1.78 |
41.82 |
|
Pure Local |
M |
16 7.60±1.53 |
50.00 |
14 99±1.66 |
29.32 | |
|
|
F |
19 |
8.33±2.07 |
56.16 |
16.16±1.55 |
31.07 |
Asdell S A. 1929. Variations in the duration of gestation in the goat. Journal of Agriculture Science (Cambridge) 19:382-396
Banda J W. 1989. Milk production potential of goats and sheep in Malawi. Phase 1. Genotypic and seasonal influences on milk yield and milk composition. Final Technical Research Report. Contract Research Committee, Ministry of Agriculture, Lilongwe, Malawi.
Banda J W and Phiri C D. 1990. Investigations into factors influencing the choice and composition of milk and milk products in Malawi. Journal of Consumer Studies and Home Economics 14.
FAO (Food and Agriculture Organization of the United Nations). 1986. 1985 FAO production yearbook. Volume 39. FAO Statistics Series 70. FAO, Rome, Italy. 330 pp.
Kasowanjete M, Stotz D and Zerfas H S. 1987. Goat development programme in Malawi. ILCA Small Ruminant and Camel Group Newsletter 8:15-21. ILCA (International Livestock Centre for Africa), Addis Ababa, Ethiopia.
Munthali J T. 1987. Cattle fattening on basal diets of maize stover and groundnut tops in Malawi. In: Little D A and Said A N (eds), Utilization of agricultural by-products as livestock feeds in Africa. Proceedings of a workshop held in Blantyre, Malawi, September 1986. ILCA (International Livestock Centre for Africa), Addis Ababa, Ethiopia. pp. 45 52.
Mwenefumbo A L and Phoya R K D. 1982. Composition and milk yield of Malawian local goat. Tropical Animal Production 7(1):71.
Peaker M. 1978. Gestation period and litter sizes in the goat. British Veterinary Journal 134: 379-383.
Wilson P N. 1957. Studies of the browsing and reproductive behaviour of the East African Dwarf goat. East African Agricultural Journal 23(2): 138-147.
Wilson R T and Durkin J W. 1985. Livestock production in central Mali: Reproductive components in traditionally managed sheep and goats. Livestock Production Science 19(3-4):523 529.
