The aim of this study was to determine the influence of increasing doses of live yeast for grazing cattle on nutrient intake and total apparent digestibility, ruminal fermentation parameters, microbial protein synthesis, nitrogen utilization, urea and creatinine metabolism, and eating behavior. Five rumen‐cannulated crossbred steers 16 mo and 350 live weights, were used in a 5 × 5 Latin square experiment design of 22‐d periods, in which the last 8 days were used for data collection. Steers were randomly designated to one treatment sequence containing live yeast added at 0, 5, 10, 15, or 20 g/day. Animals were individually allocated in paddocks (0.3 ha) uniformly covered with Urochloa brizantha cv. Marandu.” A quadratic response was observed for supplement intake (16.5 g/day), organic matter intake (7.5 g/day), crude protein (CP) intake (12.34 g/day), and starch intake (11.11 g/day). The total apparent digestibility of dry matter, CP, neutral detergent fiber, and starch increased linearly with the addition of live yeast. A quadratic response was observed for propionate concentration (7.71 g/day), butyrate (6.5 g/day), and total fatty acids (5.94 g/day). A quadratic response was also observed for nitrogen intake (14.88 g/day) and fecal nitrogen excretion (8.65 g/day. Overall, live yeast supplementation enhanced ruminal fermentation and nutrient utilization in beef steers finished on intensive pasture systems, with an optimal inclusion level of approximately 10 g/day of Saccharomyces cerevisiae (2 × 10 10 CFU/g) .
Oliveira et al. (2026) studied this question.