Protein Requirements of Cows Fed High Concentrate Rations

In Experiment I, 96 mulriparous Holstein cows were assigned at calving to rations containing 13.2, 14.4, and 15.5~ crude protein in dry matter. Daily dry matter intake per cow was 4.2 kilograms corn silage, 5.9 kilograms alfalfa hay, and 10.8 kilograms concentrates. In Experiment II, 88 cows at calving were assigned to rations with 13.9 and 15.8~ crude protein in dry matter. Daily dry matter intake was 3.8 kilograms corn silage, 8.4 kilograms alfalfa hay, and 10.0 kilograms concentrates. Amount of concentrate offered was reduced to 4 kilograms per cow daily in each experiment if milk production declined to less than 18 kilograms daily or the cow gained more than 45 kilograms body weight over calving weight. In both experiments cows were offered either 115 or 170~ of maintenance energy needs during the 60-day dry period resulting in 2 X 3 (Experiment I) and 2 X 2 (Experiment II) factorial arrangements of treatments.