SUMMARY
This study investigated the impacts of dietary yeast culture (Saccharomyces cerevisiae) supplementation on rumen fermentation, nutrient digestibility and rumen microbial population in sheep. Three digestibility trials were carried out using fifteen Sohagi rams randomly assigned into three groups (5 rams/ each). Each trial lasted for three weeks, the first two weeks were considered as a preliminary period followed by one week collection period.The groups were a control group fed basal diet without yeast supplement and treated groups fed either 0.5 (T1) or 1% (T2) yeast culture (YC) mixed with concentrate diet. All animals were fed 60% of their requirements as concentrate mixture while, chopped corn stover was given as roughages ad libitum. The results referred that, the digestibility of dry matter, organic matter, crude protein, crude fibre, neutral detergent fibre and hemicellulose were significantly (P<0.05) improved for yeast treated diets compared with basal diet. Live yeast culture either 0.5 or 1% in concentrate diet increased (P <0.05) the pH, volatile fatty acids (VFAs), acetate and propionate, while rumen ammonia nitrogen concentration was decreased (P<0.05). Live yeast supplementation (0.5 or 1%) improved (P<0.05) N retention. The rumenal bacterial and protozoal counts increased (P<0.05) due to YC supplementation. In conclusion, dietary live yeast culture (S. cerevisiae)
particular 1% of concentrate mixture may improve nutrient digestibility, fermentation patterns and rumen microbial population.