Effect of a Saccharomyces cerevisiae culture on nutrient digestion in lactating dairy cows

The digestive effects of a Saccharomyces cerevisiae culture were investigat ed. Four cows in early lactation that were fitted with ruminal and duodenal cannulas were used in a crossover design. The diet, which consisted of 60% corn silage and 40% concentrates, was supplemented or not supplemented wit h a daily dose of 50 g of premix containing 0.5 g of S. cerevisiae (6 x 10( 8) cfu/g of premix). Total and ruminal digestibilities of organic matter, d uodenal flows of non microbial and microbial N, solid and liquid turnover r ates, ruminal protozoal numbers, pH, ammonia N and volatile fatty acid conc entrations, and concentrations of some plasma metabolites were not modified by the addition of S. cerevisiae. Ruminal dry matter content increased whe n S. cerevisiae was supplemented to the diet. In situ ruminal degradabiliti es of dry matter and neutral, detergent fiber from corn stalk and of N from soybean meal were not modified; degradability of acid detergent fiber from corn stalk increased (32.5% vs. 26.3%) with the addition of S. cerevisiae. A short-term increase in N degradation was observed after 4 and 8 h of inc ubation. This experiment showed no effect of S. cerevisiae on most quantita tive digestive events; however, a positive transitory postprandial effect o n some parameters of microbial activity was observed.