Diets that contain less than 50 percent forage fiber when fed with 20 percent dried distillers grains with solubles may trigger milkfat depression. Researchers at South Dakota State University purposely fed this diet to find out if adding yeast culture to the diet could keep milk fat from decreasing. The researchers still saw “slightly lower milk fat yield in the diets containing 20 percent distillers grains,” according to Arnold Hippen, dairy science professor at South DakotaStateUniversity. However, the addition of 14 grams of yeast culture per head per day benefited milk production and milk protein yield. Milk production improved by 3.5 pounds per head per day compared to cows fed the same diet without yeast-culture supplementation.