Responses of Dairy Cows to Additions of Distillers Dried Grains with Solubles in Alfalfa-Based Diets

Abstract

Twenty-four Holstein cows in wk 3 through 12 of lactation were used to evaluate distillers dried grains with solubles as a protein source for alfalfa-based diets. Diets were formulated containing 0, 10.1, 20.8, or 31.5% distillers dried grains with solubles. Crude protein in these diets was 13.9, 16.0, 18.1, and 20.3%. Milk yield increased linearly with increasing dietary CP, whereas DMI was not affected. Dry matter intake averaged over 4% of BW for all treatments. Intake of undegraded intake protein was .93, 1.27, 1.63, and 1.97 kg/d. Yields of milk protein, casein, and lactose all increased linearly with increasing dietary CP. The proportion of milk N as whey N decreased, whereas N as NPN increased, with increasing dietary CP. Plasma urea N and essential and branched-chain AA increased linearly, and nonessential AA decreased linearly, with increasing dietary CP. Increasing the concentration of CP in the diet from 13.9 to 18.1% by the addition of distillers dried grains with solubles was beneficial to cows fed alfalfa-based diets in early lactation. Little additional benefit was observed by feeding greater than 18.1% dietary CP. © 1992, American Dairy Science Association. All rights reserved.