EFFECTS OF FEATHER MEAL AT 2 PROTEIN CONCENTRATIONS AND YEAST CULTURE ON PRODUCTION PARAMETERS IN LACTATING DAIRY-COWS

Thirty-six early to midlactation Holstein cows were used in a 2 x 3 factorial design to determine effect of three concentrations of hydrolyzed feather meal (0, 3, or 6% of dietary DM) at two protein concentrations (14 or 18% of DM) in TMR on DMI, milk production and composition, and nutrient digestibilities. Diets (DM) contained 50% com silage and 8% soybean hulls and were balanced with com meal, soybean meal, and hydrolyzed feather meal. The experiment was conducted over three 28-d periods. Yeast (0 or 57 g/d) was fed continuously to half of the cows throughout all three periods. Concentration of feather meal had no effect on DMI and milk fat percentage at either protein concentration. A curvilinear effect of feather meal on milk production showed 3% feather meal to be beneficial at 14% CP but not at 18% CP. Milk protein percentage was affected adversely by feather meal concentration. Treatment with yeast culture decreased DMI (22.0 vs. 22.9 kg/d), but milk and SCM production and milk fat and protein percentages were not affected. Increasing feather meal had a negative linear effect on CP digestibility and a positive linear effect on NDF digestibility. Increasing dietary CP from 14 to 18% increased CP and NDF digestibilities. Yeast culture tended to increase NDF digestibility. Increasing dietary CP caused increases in blood urea N concentrations; increasing feather meal resulted in curvilinear increases in blood urea N. Dietary yeast culture decreased blood urea N.