621. Winter feeding of dairy cows: III. The influence on milk yield of high and low protein concentrates, each fed at two levels in addition to dried grass and grass silage

1. In a winter-feeding experiment with eight Ayrshire cows the effects of feeding a high- and a low-protein concentrate at two rates (4 and 2 lb./gal.), in addition to dried grass and silage, were studied. 2. With these cows and the feeds used increasing the rate of concentrate feeding from 2 to 4 lb./gal. increased the total dry-matter consumption by 2 lb./day and the average milk yield by 1·2 lb./day. 3. For every 1 lb. increase in concentrate fed there was a decrease of 0·68 lb. grass dry matter eaten. 4. The level of protein in the concentrates had no effect on total dry-matter intake, and only a slight, though positive, effect on milk yield. 5. It is concluded that in this work where the diet was made up with high-quality dried grass and silage, feeding either a high- or a low-protein concentrate mixture at the rate of 2 lb./gal. milk gave the greatest profit margin per cow.