Extruded Soybeans and Corn Gluten Meal as Supplemental Protein Sources for Lactating Dairy Cattle

Abstract

Holstein cows in early lactation were used to compare three combinations of extruded whole soybeans and corn gluten meal to soybean meal. Treatments were (as a percentage of supplemental crude protein) 100% soybean meal; 75% whole soybeans extruded at 149C, 25% corn gluten meal; 50% extruded soybeans, 50% corn gluten meal; and 25% extruded soybeans, 75% corn gluten meal. Diets were formulated to he 37.5% corn silage, 12.5% alfalfa cubes, and 50% concentrate (dry matter). Dietary crude protein was 15.7% of dry matter, and supplemental protein sources supplied 27% of total dietary protein. Diets were fed as total mixed rations and data were collected from 4 to 116 d postpartum.