Influence of Different Levels of Malic Acid on Rumen Fermentation in Dairy Cow in Vitro

Two with permanent ruminal fistulae dairy cows were selected to contribute rumen liquid.The rumen liquid which were supplemented malic acid of 0,4,8 and 12 mmol/L(the final concentration) respectively were used in batch culture technique to determined the indexes of rumen fermentation after incubated 3,6,9,12,18 and 24 h in vitro.The concentration of malic acid in control group was 0 mmol/L.The results showed: compare with control group,the indexes of rumen incubated liquid pH,NH_3-N,TVFA and BCP were increased with varying degrees by supplemental malic acid in different levels,and NDF degradation rates of rumen incubated residue were increased significantly(P0.05).Supplemented 8 mmol/L malic acid to the experimental diet of dairy cows is propitious to promote rumen fermentation in vitro.The supplemental level of 80 g/d malic acid in dairy diets was suggested.