Effect of Selenomonas ruminantium alone,or in combination with yeast cultures,on in vitro rumen bacterial fermentation

In vitro batch culture techniques were used to investigate the effect of S.ruminantium alone and in combination with yeast cultures on rumen bacterial fermentation.When Leymus chinensis was used as a substrate,yeast culture addition increased the acetate,propionate,butyrate,valeric acid,isovaleric acid and TVFA contents (P0.05),and reduced lactic acid content,but had no significant effects on pH value,isobutyrate or ratio of acetate to propionate (P0.05).The ratio of acetate to propionate and the lactate concentration were reduced (P0.05),and acetate,propionate,n-butyrate,isobutyrate,isovaleric acid,TVFA content and pH value were improved by S.ruminantium supplementation (P0.05).There was no significant interaction between pH value,acetate,propionate,butyrate,isovaleric acid or TVFA content between S.ruminantium and yeast cultures (P0.10).When maize was used as a substrate,live-yeast culture addition increased pH value,acetate,propionate,n-butyrate,isobutyrate,isovaleric acid and TVFA content (P0.05),and reduced lactate concentration and the ratio of acetate to propionate (P0.05),but there was no significant effect on isobutyrate content (P0.10).pH value,acetate,propionate,butyrate,isovaleric acid and TVFA content were improved by S.ruminantium,and S.ruminantium supplements lowered lactate content and the ratio of acetate to propionate (P0.05).There was a significant interaction effect on pH value,lactate,acetate,propionate butyrate,TVFA content and the ratio of acetate to propionate between S.ruminantium L9 and yeast cultures (P0.05).When starch was used as a substrate,S.ruminantium had an increase in pH value and acetate,propionate,butyrate and TVFA content (P0.05),but a decrease in lactate concentration and the ratio of acetate to propionate (P0.05).Yeast culture supplement increased pH value and acetate,propionate,butyrate and TVFA content (P0.05),but had no effect on valeric acid,isobutyrate content or the ratio of acetate to propionate (P0.10).A significant interaction effect was observed on pH value,acetate,propionate,butyrate,TVFA,lactate content and the ratio of acetate to propionate between S.ruminantium and yeast cultures (P0.05).S.cerevisiae L9 can be considered a good strain which might tolerate the adverse conditions in the gastrointestinal tract when used as a live microbial feed supplement in the diet of the animals.Compared with the addition of yeast or S.cerevisiae alone,the live-yeast cultures combined with S.cerevisiae L9 more effectively to reduce lactate and maintain a stable ruminal pH.