Impact of DDGS feeding on the composition of milk and baby Swiss cheese

Abstract

Late blowing in Swiss cheese, a result of unwanted gas production during ripening, is unacceptable to consumers, and causes economic loss to manufacturers. Cheese processors have raised concerns that feeding dried distillers’ grains with soluble (DDGS) to cows leads to this defect, in part, because of Clostridial spores. In this study, the effect of feeding DDGS to lactating dairy cows on composition and quality of milk and baby Swiss cheese was examined. Thirty healthy multiparous and mid-lactation Holstein cows were assigned randomly to one of three dietary treatment groups (10 cows per treatment group): (1) total mixed ration (TMR) with no DDGS, (2) TMR with 10% DDGS by dietary DM, and (3) TMR with 20% DDGS by dietary DM in a 3 × 3 Latin square with repeated measures. One complete milking from all cows within a treatment was collected and pooled for cheese- making trials, twice within each month of the three-month study. Additionally, individual milk samples from three milkings of a day were collected weekly, and proximate analysis was carried out on pooled individual milk samples. Milk used for cheese production was standardized to 0.88 fat:protein, and pasteurized before making baby Swiss cheese. The ~3.5 31 kg cheese blocks were vacuum packed and allowed to ripen (10C, 7 days; then 22C, 21 days), then cooled (4C, 60 days). Milk, cheese, TMR, DDGS and manure were analyzed for gas formation by Clostridial spores. Within 48 hours incubation in modified reinforced clostridium lactate medium, tubes containing milk, cheese, TMR, or manure showed gas formation. Conversely, DDGS used in our study was not a source of gas-producing spores. Feeding 10% and 20% DDGS decreased milk fat content (P solids nonfat (P Swiss cheese had typical propionic acid Swiss cheese aroma. Regardless of diet treatment, pinholes, slits, and cracks were seen throughout most cheeses. Feeding of DDGS increased the amount of long-chain unsaturated fatty acids and decreased short-chain and most medium-chain fatty acids in the baby Swiss cheese. Although feeding cows with DDGS, modified milk composition and subsequently the cheese composition, DDGS could not be blamed as a source for gas-producing spores or for quality defects in Swiss cheese, but, rather, the gas-producing spores likely originate from the cow herself or the environment.