The use of station and field tests for the improvement of milking performance in dairy cattle. III. Breed differences in the yield of milk and butterfat from the fore and rear quarters of the udder

Abstract

The analysis was concerned with selective advantage as a possible cause of differences between breeds and individual animals in the relative proportions of milk obtained from the fore and rear quarters of the udder.Danish Jersey cattle were found to yield a significantly higher proportion of milk from the fore quarters than Danish Red and Danish Black Pied cattle (47% ν. 45% and 44% respectively).Very strong genetic relationships between the proportion of milk obtained from the fore quarters and lactation yields of milk and butterfat (rg = 0·92, 0·85) in the Jerseys, and correspondingly weak genetic relationships in the other two breeds, suggest that breed differences have arisen as a result of selection for productive performance operative upon different genetic relationships between production and the process controlling the partition of milk in the udder. It is suggested that differences between the breeds are likely to increase in the future.