The effect of undernutrition before calving on the quantity and composition of milk produced by two-year-old heifers

Abstract

Six pairs of 2-year-old monozygous twin heifers were used to determine the effect of underfeeding for 10 weeks prior to calving. Those which had been well fed before calving produced more milk than their sisters which had been poorly fed. There was no effect on milk or butterfat composition, probably because none of the animals lost much weight after calving. The effect of the treatment differed markedly between twin pairs, the maximum difference in milk yield being 2866 lb., the minimum 135 lb., and the mean 1057 lb. for 270 days' lactation. The ratios of between-twin-pair to within-twin-pair variance for butterfat, total protein and lactose percentages of the milk were as follows: