Performance of dairy goats fed isonitrogenous diets containing soybean meal or hydrolyzed feather meal during early lactation

Lactating dairy goats were utilized in a 105-day continuous feeding experiment to compare hydrolyzed feather meal with soybean meal as a protein supplement for milk production. Treatments were isonitrogenous and isoenergetic diets containing soybean meal or hydrolyzed feather meal. Fifty percent of total dietary nitrogen was provided by test proteins. Ruminal ammonia nitrogen (16.1 vs 4.7 mg/dL) and total volatile fatty acids (79.5 vs 69.6 mM) were lower in goats fed hydrolyzed feather meal. Dry matter intake (2.90 vs 2.52 kg/day), live body weight (48.1 vs 47.7 kg), and milk yield (3.20 vs 3.16 kg/day) were similar between treatments. Milk protein content and yield, true protein N, and casein N were lower in goats fed hydrolyzed feather meal. Serum total protein and urea N were lower in goats fed hydrolyzed feather meal while plasma glucose was similar between treatments. Feed efficiency (kg 4% fat-corrected milk/kg dry matter) was slightly higher in goats fed hydrolyzed feather meal and no differences were observed in energy and protein efficiencies. Limitation in microbial protein synthesis due to suboptimal NH3-N concentration in the rumen and quality of protein available for intestinal absorption may be important in the utilization of hydrolyzed feather meal for milk production.