Abstract
From July 1975 to January 1977, 225 cows in three autumn-calving dairy herds were condition-scored, weighed and milk-recorded at monthly intervals. The condition score at calving was related to the ability of the animal to achieve potential milk yield. This potential milk yield was denned by the lactation curve prediction. Animals below condition score 2 at calving did not achieve their predicted milk yield, and those above condition score 2½ yielded more than their predicted milk yield. Cows in poor condition at calving gave low, late peak milk yields with a high persistency, and those in good condition at calving gave high, early peak milk yields with a lower persistency. A positive relationship of 25 ± 1·6 kg live weight per unit of condition score was established within cows in months 1 to 7 of lactation. After month 7 of lactation foetal development caused changes in live weight without changes in score.