Effects of variable sources of distillers dried grains plus solubles on milk yield and composition.

This study compared diets supplemented with distillers dried grains plus solubles originating from whiskey distilling with those from fuel alcohol production or soybean meal. Forty-eight cows in mid and early lactation were offered a different dietary treatment in each of three 28-d periods. Dietary design included three supplements at 14 or 18% CP of dietary DM, with or without blood meal. Additionally, a third, darker, fuel ethanol source was added at 14 and 18% CP without blood meal during period 3 to incorporate greater variation in quality of distillers grains. No detectable differences occurred in DMI or in any variables because of blood meal. Milk yield was higher when cows were fed diets at 18% rather than at 14% CP. Cows fed the two lighter distillers grains diets yielded .8 kg/d more milk than cows fed soybean meal diets, and cows fed whiskey distillers grains yielded 1.3 kg/d more SCM than cows fed diets with darkest distillers grains. Milk protein percentage was depressed when the darkest distillers grains were fed. Distillers dried grains plus solubles can provide an excellent substitute for soybean meal and corn in dairy cow diets.