Effects of the Inclusion of Yeast Culture (Saccharomyces cerevisiae) in the Diet of Holstein Cows on Milk Yield and Composition in Early Lactation

The effect of including a yeast culture (Saccharomyces cerevisiae; 1010 cfu/g; YC) in diets for lactating Holstein cows was evaluated. One hundred thirty-eight cows in early lactation were randomly assigned into two groups of 69 cows each, according to their days in milk and parityand were fed a basal diet without (CTRL diet) or with the addition of 15 g YC/cow/d (yeast diet) for 7 weeks. The basal diet contained 17.7% CP and 31.8% NDF on DM basis. The inclusion of YC increased (P=0.04) feed intake compared to the CTRL diet. The YC did not affect (P>0.05) serum total protein, albumin and globulin concentration, as well as albumin/globulin ratio, and urea-N. The YC increased serum glucose concentration (P=0.002) and decreased serum cholesterol (P=0.001) levels compared to CTRL group. Addition of YC did not affect (P>0.05) actual and energy corrected milk yields and daily milk total solids, solids-notfat, protein, and milk energy content and output; however, YC increased milk fat (P=0.04) and lactose (P=0.028) daily yields. Increased milk fat concentration (P=0.027) and lactose (P=0.004) were observed in cows fed the yeast diet. It was concluded that YC at 15 g/cow/d during the first 7 weeks of lactation increased feed intake, and milk fat concentration and lactose without affecting daily milk yield and milk efficiency.