Effects of dietary concentrate level on ruminal fermentation and microbial growth efficiency in dual flow continuous culture

摘要

A dual-flow continuous culture system was used to study the effect of dietary concentrate levels (0, 20, 40, 60, 80, 100%) on rumen fermentation characteristics and microbial growth efficiency. Dilution rates of solid and liquor fractions were set at 0.04/h and 0.08/h, respectively. The results showed that increasing concentrate level resulted in increased digestibilities of DM and OM, but in decreased digestibilities of NDF and ADF. Also, as the concentrate level increased, there was a decrease in ruminal pH, ammonia concentration and an increased total VFA production. Increasing dietary concentrate level, the molar proportion of propionate linearly increased, but that of acetate decreased. As dietary concentrate level increased, daily microbial N production (DMNP) and microbial growth efficiency (MOEFF) increased. The maximum DMNP and MOEFF were achieved at 80% dietary concentrate level.