Factors affecting birth weight and growth rate in Friesian X Bunaji calves
Calving records from 1984 - 1989 were studied to determine the influence of rearing method, sex of calf, season of birth, dam breed and year· of birth on body weight at birth, 3, 6 and 12 montl1s of age in Friesian x Bunaji calves. The mean weights of calves at birth, 3, 6 and 12 months of age were 22.0, 68.2, 96.7 and 137.4 kg, respectively. Sex of calf had a significant effect, with male calves being heavier than the females by 1.2, 5.9 and 9.7 kg at birth, 3 and 6 months of age respectively. The effect of season of birth on calf body weights was not significant except at 6 months of age, when calves horn during the wet season were heavier (P<0.01) than those born . in the hnrmattan period by 9.5 kg. Year of birth had a highly significant effect (P<0.01) on culf weights from birth to yearling. Method of rearing and dam breed had no significant influence on all the weights. The results suggest the need to develop correction factors for standardisation of weight records when comparing dams on the basis of body weights of their calves.
Key words: Birth weight; Growth rate; Friesian-Bunaji; Calves.