The effects of a low-protein food supplement on the yield and composition of milk from grazing dairy cows and on the composition of their diet

Abstract

1. Dried molassed sugar-beet pulp was fed to dairy cows grazing abundant intensively managed pastures in two trials (spring and autumn), each of 8 weeks' duration. A change-over design (four 14-day periods) with twenty-four cows was employed in each trial. Apart from six changes for the autumn trial, the same cows were used throughout.2. In the spring trial (May–July) 8 lb. beet pulp were fed daily. The herbage dry matter consumed contained, on average, 16·8% crude protein, and the general mean milk yield was 38 lb./cow/day. The milk yield of the supplemented cows was 1·3 lb. (3·7%) greater than that of the control animals (P< 0·05).3. In the autumn trial (August–October) 10 lb. beet pulp were fed daily. The herbage dry matter consumed contained 23·8% crude protein and the general mean milk yield was 27 lb./cow/day. The milk yield of the supplemented cows was 2·9 lb. (11·3%) greater than that of the control animals (P< 0·001).