Factors affecting body weight of East African and Galla goats

Abstract

A total of 617, 1009, 1180, 1644 and 2865 records of body weights of Galla and East African does at 2, 3, 4 5, and ⩾ 6 years of age, respectively, were analyzed by least-squares methods. Breed and sex of fetus had no significant effects on body weight of dam, but breed of doe, year, type of birth, season and pregnancy status were significant ( P < 0.05). Does averaged 1.0 to 2.0 kg heavier in the cooler, dry season than in the rainy, warm season. Galla does were approximately 15% heavier at all ages than East African does. Mature weights averaged 31 kg for East African and 35 kg for Galla. Weight increase due to fetal growth and other pregnancy effects was 6.2 kg (21%) for East African and 6.0 kg (18%) for GAlla. Weight loss during lactation was −0.6 kg (2%) for East AFrican and −1.9 kg (6%) for Galla. Multiplicative adjustment factors for pregnancy and lactation effects were developed for both breeds. Factors differed for the two breeds, for different age groups and were sufficiently large to warrant adjustment for these effects in analyses of body weights. The factors reported may serve as a guide for adjusting body weights of does of other breeds under other conditions if more appropriate values are lacking. In general, these results show that important errors and biases may occur in estimates of average doe body weights if pregnancy and lactation effects are not taken into account.