Effects of Feather Meal at Two 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 corn meal.soybean meal, and hydrolyzed feather meal.The experiment was conducted over three 28-d periods.Yeast (0 or 57 gld) 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% CPo 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