DDGS Feeding Modifies Milk Composition: Investigating Impact on Cheese Quality

Iowa State University/Stephanie Clark and Donald Beitz

Clostridium tyrobutyricum are spore-forming and butyric acid-lactate-fermenting bacteria that release large amounts of gas upon fermentation of lactose. Late blowing in cheese is unacceptable to consumers and it reduces the economic value of cheese. Appearance of splits and cracks is due to unwanted gas production during the ripening of Swiss cheese. Dairy farmers suspect feeding DDGS might be a reason for such defects in cheese. With ethanol production being a major industry in the Midwest, utilization of DDGS in animal feeding is inevitable and generally economical. Consequently, it is of high priority to farmers in the Midwest that we investigate the effects of DDGS inclusion in the diet of dairy cows on quality markers of milk as they relate to cheese production.

The research was designed to investigate the impact of lactose, sulfate and thiosulfate on quality of Baby Swiss cheese. Additionally, because of the industrial shift from a full-fat dried distillers grains (FF-DDGS) to reduced-fat dried distillers grains (RF-DDGS), we will investigate the effect of feeding two types of reduced-fat DDGS that contain two different concentrations of fat (3-4% and 8%) on feed efficiency and usability of milk for Swiss cheese production. It is expected that high concentrations of lactose, sulfate and thiosulfate in milk impair the growth and metabolism of the specific microorganisms responsible for high quality Baby Swiss cheese.