Evaluation of Age at First Calving and Number of Services per Conception Traits on Milk Yield Potentials of Holstein Friesian x Bunaji Crossbred Cows

The objective of the study, was to determine the optimum Holstein Friesian (HF) inheritance for a shorter Age at First Calving (AFC) and Number of Services per Conception (NSC) on milk yield potentials of HF x Bunaji (BJ) crossbred cows. Data of HF and BJ dairy cows with 75, 87.5 and 100% HF inheritance kept at the West African Milk Company (WAMCO) farm in Vom, Plateau State, Nigeria, between 1998 and 2004 were used for the study. The independent variables considered included genotype, birth year, birth season and service season, while AFC and NSC were the dependent variables. The data were analyzed with the General Linear Model (GLM) and where differences were observed, the least square mean obtained for the effects were compared using the Probability of Difference (PDIFF) procedure of Statistical Analysis System (SAS). Results showed that calf birth year significantly (p<0.05) influenced AFC and NSC, while genotype was significantly (p<0.05) expressed in NSC only. With good management, the 87.5% HF crossbreed cows exhibited superior genetic potential (AFC and NSC). Breeding of the crossbreeds can be done in early wet season, when NSC is low and fertility is high.