Barley distillers grains as a protein supplement for dairy cows.

Dried distillers grains produced from a mix of 65% barley and 35% corn were evaluated in digestion and lactation experiments. Dried barley distillers grains had 56% NDF, 29% CP, 3% amino acid N, 2.5% NDIN (55% of total N), and 1.8% ADIN (39% of total N). Wet barley distillers grains had 38% NDF, 27% CP, 2.7% amino acid N, .5% NDIN (12% of total N), and .8% ADIN (19% of total N). Digestibility of DM and N was similar among lactating dairy cows fed diets containing approximately 25% corn silage DM, 15% alfalfa silage DM, 15% alfalfa hay DM, plus varying amounts of a corn-barley concentrate mix and supplemental CP from soybean meal, barley distillers grains, or from 1:1 mixture of soybean meal and barley distillers grains. Digestibility of ADIN, NDF, and ADF increased with increasing amounts of barley distillers grains in the diet. Similar diets were fed to 60 Holstein cows for 84 d in a lactation experiment. Source of supplemental protein did not affect milk production (22.5 kg/d), FCM (20.4 kg/d), milk fat percent (3.6%), or DM intake (19.0 kg/d). Milk protein percent was decreased by feeding barley distillers grains. It was concluded that barley distillers grains were an acceptable protein source for dairy cows and that ADIN and NDF might not be appropriate measures of the nutritional value of this product.