Selection Indices for Milk and Fat Yield of Holstein-Friesian Dairy Cattle

Abstract

Estimates of heritability, phenotypic and genetic correlations for milk and fat yield and fat per cent were obtained from the single lactation records of 20,024 daughterdam pairs of the Holstein-Friesian breed. The estimates of these parameters were used to construct selection indices for milk and fat yield. The results indicated that a selection index for milk yield alone would be expected to be the most effective in improving milk and fat yield of dairy cattle.