Livestock production in central Mali: environmental factors affecting weight in traditionally managed goats and sheep

Abstract

A study of the factors affecting weight in traditionally managed goats and sheep in central Mali was undertaken during 1978–84. Sheep were heavier than goats at all ages. Birth weights of goats (2·2 kg) were significantly affected by year and season of birth, parity, type of birth, sex and system (rain-fed millet or irrigated rice). Lamb birth weights (2·9 kg) were affected by all these sources of variation except year. System did not exert a significant influence on kid weights at 30 (4·3 kg), 90 (7·5 kg) or 150 days (10·5 kg) but the random effects of flocks and dams and the fixed effects of season, year, parity, type of birth, sex and the interaction of season × year were all significant at all three ages except for year at 30 days. Lamb weights (5·7, 11·1 and 15·5 kg) were significantly affected at all three ages by all sources of variation except season × year effects at 90 and 150 days. Repeatabilities of lamb weights were higher than of kids, probably due to milk being taken for human consumption from goats. There were few significant effects at post weaning to 730 days except those related to sex. Post-partum weights of goats (26·0 kg) were not affected by system, by the type of parturition nor by the sex of the young but were affected by season and year of parturition and by parity. Ewe post-partum weights (30·6 kg) were affected only by system and parity. Changes in weight over the year, pooled for 7 years, in specific age and sex groups averaged proportionately about 005 above and below the annual mean. Weights of mature animals were about 0·05 lower in 1984 than in 1978. Seasonal and long-term effects on weight are much less marked in small ruminants than in cattle under the same management system in the central Mali environment and the allocation of future research effort should take into consideration the relative advantages of the two types of stock.