Storage and Utilization of Brewers Wet Grains in Diets for Lactating Dairy Cows

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Abstract
Brewers wet grains were treated with NH3 at 0, 2, or 4% of dry matter, compacted in plastic pails, and exposed to aerobic storage for 3, 7, or 10 d. Portions were compacted in polyethylene bags, sealed with twine, and left to ensile for 7, 14, or 28 d. During aerobic storage, water-soluble carbohydrate increased at high NH3 but decreased at 0 and 2% NH3. Mold growth and spoilage were inhibited by 4% NH3. For ensiled grains, NH3 delayed increases of lactate, presumably by inhibiting fermentation. Water-soluble carbohydrates increased to d 14 at 4% NH3, then tended to decrease with longer ensiling. The 4% NH3 addition effectively preserved wet grains in aerobic and anaerobic storage, but 0 and 2% did not. In another study, lactating Holstein cows were fed a basal diet of corn silage, alfalfa hay, ear corn, and a mineral-vitamin mix for 70 d. Treatments substituted either 25.6% fresh brewers wet grains, 26.3% ensiled brewers wet grains, or 14.7% fresh brewers wet grains plus 0.72% urea for 14.3% soybean meal. Daily dry matter intakes for the respective treatments were 25.2, 21.9, 20.8, and 22.8 kg. Milk yields and milk composition were not significantly different. Feed efficiency and income over feed costs were greater for brewers wet grains than soybean meal. Urea added to brewers wet grains was the most profitable diet and appears to be an economical alternative to soybean meal as a protein supplement for lactating dairy cows under these conditions.

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