Abstract
Reproductive efficiency and milk production traits were studied using crossbreeding data from a composite herd involving Brown Swiss (BS) and N'dama (ND) cows raised at the University of Ibadan Teaching and Research Farm over a 19-year period. The overall age at first calving (AFC) and calving interval (Cl) were 36.38 days and 414.57 days, respectively. The AFC and Cl were significantly (P < 0.05) higher among the BS and ND cows compared to their crossbred counterparts except the F1-ND backcrosses. The AFC decreased with reduction in the proportion of ND blood among the crossbred progenies. Calving rate (CR) demonstrated a strong heterotic advantage. While the observed CR among the BS and ND was 41.35% and 29.71%, respectively, the average CR among the various crossbreds ranged from 46.30% to 63.9%. Individual and maternal heterosis was large and positive. The average lactation milk yields among the genotypes was 1443.9 kg in an average lactation length of 272.84 days with a coefficient of variation of 42.5. The effect of genotype on all the milk production traits studied was significant (P < 0.05). Among the crosses, milk yield was highest among the F1 animals, which also had the longest lactation length of 305.7 days. For adjusted 205 day and annual milk yield, the best performance was recorded among the F1-ND in the crossbred group.
