Milk production and composition from cows fed wet corn distillers grains

Twelve lactating Holstein cows were utilized in a repeated switchback desig n to evaluate milk production and milk fat composition responses to wet cor n distillers grains. Total mixed diets consisted of 31.4% corn silage, 18.4 % alfalfa hay, and either 50.2% of a concentrate mix that contained mostly corn and soybean meal or 19.4% of a concentrate mix that contained mostly c orn and 31.2% wet corn distillers grains. The first 4 wk of each 6-wk perio d were for adaptation to diets; data were collected during wk 5 and 6 of ea ch period. Although dry matter intake (22.1 vs. 19.7 kg/d) was lower when c ows were fed the wet corn distillers grains diet, milk production (30.7 vs. 30.8 kg/d) was similar for cows fed both diets. Milk fat (3.60 vs. 3.85%) was slightly higher, and protein (3.06 vs. 2.84%) was lower, when cows were fed the wet corn distillers grains diet. Milk fat from cows fed wet corn d istillers grains contained lower concentrations of saturated fatty acids an d higher concentrations of long-chain and unsaturated fatty acids. The feed ing of wet corn distillers grains increased the proportion of unsaturated f atty acids in milk fat without changing milk production.