<b>Effect of protein levels and sources on performance and nutrient utilization by lactating dairy cows</b> - DOI: 10.4025/actascianimsci.v29i3.570

Abstract

Five ruminally cannulated lactating dairy cows, producing 27 kg day^-1 of milk, were used in a 5 x 5 Latin Square design. Diets contained different protein sources: control, urea, soybean meal, roasted soybeans and corn gluten meal. The control diet featured 13.4% crude protein, and the other diets 16.5%. Dry matter intake, milk production, milk fat content and yield, and feed efficiency were not affected by the treatments. Feeding roasted soybeans decreased milk protein content (p < 0.05). The treatments had no effect on the total tract digestibilities of dry matter, organic matter, starch and neutral detergent fiber; however, crude protein digestibility was reduced with the control and roasted soybeans diets (p < 0.05). Feeding urea increased plasma urea-N (p < 0.05). The treatments had no effects on plasma glucose concentration.