The effect of undernutrition after calving on the quantity and composition of the milk produced by dairy cattle

Abstract

Fourteen pairs of monozygous twin cows of mixed ages were used to determine the effect of underfeeding from the 3rd to the 8th week inclusive after calving on milk and butterfat production and on the composition of the milk. Those cows which were well fed over the 6-week period produced more milk and a larger weight of butterfat than their sisters which had been poorly fed. The milk from the well-fed cows had a lower percentage of butterfat, but higher percentages of solids-not-fat and total protein, than the milk from the poorly fed cows. The complete lactation averages failed to show statistical significant differences in all characteristics except in the case of solids-not-fat percentage. The mean difference between the two groups for solidsnot-fat was found to be highly significant. In general, the results support the conclusions of other workers, that underfeeding dairy cows may depress the solids-not-fat content of the milk. It appeared that differences between the two groups in butterfat percentage over the 6-week experimental feeding period were strongly correlated with differences in weight changes and that the small amount of variance associated with milk yield differences was not significant.