Phenotypic relationship between body weights of Friesian-Bunaji crossbred heifers and their subsequent milk production

Abstract

The study reported was conducted to investigate whether fast growing heifers eventually become good milkers in a bid to assist dairy farmers in selecting their replacement stock at an early age. The data analysed consisted of 549 body weight records at birth, 3, 6, 9 and 12 months of age of Friesian-Bunaji crossbred heifers, as well as 840 records on their subsequent lactation length, total lactation yield and estimated 305-day yield collected over a 23-year period (1967-1989). Phenotypic correlations between body weights at fixed ages were all positive and highly significant (P<0.0l), ranging from 0.30 to 0.79. Correlations among milk traits were also positive and highly significant, the range being 0.74 to 0.95. Correlations between body weights and milk traits on the other hand, were very low and non-significant, ranging from 0.01 to 0.14. Equations fitted from simple, multiple and polynomial regressions of body weights on total lactation yield gave very low R2 values. It was therefore concluded that body weights at birth, 3, 6 and 12 months of age have little value in the prediction of future milk yield of Friesian-Bunaji heifers.