Effects of B_(12) on Rumen Fermentation and Fibre Degradation in Vitro

An in vitro study was conducted to study the effects of different B_(12) levels on fermentation and fibre degradation.Results showed that: the addition of B_(12) had no significantly effect on the total counts of protozoa and bacteria, the ammonia-N concentration,pH value,the molar percentage of acetate,propionate,butyrate,valerate,isobutyrate,isovalerate,the ratio of acetate to propionate,TVFA concentration(P0.05),but the number of bacteria(P=0.086) and TVFA concentration(P=0.081) had an increasing tendency with the increase of B_(12) level.The addition of B_(12) significantly increased the activity of CMCase and Xylanas,and the degradation of DM and NDF(P0.05),but there was no significantly difference in the activity of Avicelase and the degradation of ADF(P0.05).The current study suggested that the addition of B_(12) had beneficial effects on fibre degradation when the diet(fermentation substrate) contained higher corn stalk.