Effects of Thiamine on Rumen Fermentation Parameters and Branched-Chain Fatty Acid Synthesis in Vitro
This experiment was conducted to evaluate the effects of thiamine on rumen fermentation parameters and branched-chain fatty acid(BCFA)synthesis by in vitro method.The experiment was divided into 6 groups with 5 replicates per group,and two batches of fermentation were performed.The 5 groups were used 0.5 g to-tal mixed ration(TMR)as the fermentation substrate,and supplemented with 15(control),30,60,120 and 240 mg/kg DM thiamine,respectively.The fermentation broth was collected after 24 h incubation at 39℃for the determination of rumen fermentation parameters,fatty acid content and branched-chain α-keto acid dehy-drogenase(BCKD)activity.The results showed as follows:1)the fermentation broth total volatile fatty acid content of 30 mg/kg DM thiamine group was significantly lower than that of control group and 120,240 mg/kg DM thiamine groups(P＜0.05),the fermentation broth total branched volatile fatty acid content of 15 and 30 mg/kg DM thiamine groups was significantly lower than that of control group and 120,240 mg/kg DM thiamine groups(P＜0.05),and the fermentation broth microbial protein content of 15,30 and 60 mg/kg DM thiamine groups was significantly higher than that of control group and 120,240 mg/kg DM thiamine groups(P＜0.05).2)The fermentation broth saturated fatty acid content of 60 mg/kg DM thiamine group was significantly higher than that of control group and 15,120,240 mg/kg DM thiamine groups(P＜0.05),the contents of unsaturated fatty acid and monounsaturated fatty acid in fermentation broth of 120 and 240 mg/kg DM thiamine groups were significantly higher than those of 30 and 60 mg/kg DM thiamine groups(P＜0.05),and the fermentation broth total fatty acid content of 60 mg/kg DM thiamine group was significantly higher than that of control group and 15 mg/kg DM thiamine groups(P＜0.05).3)The contents of isomeric branched chain fatty acid(Iso),trans isomeric branched chain fatty acid(Anteiso)and BCFA in fermentation broth of 30 and 60 mg/kg DM thiamine groups were signifi-cantly higher than those of the control group(P＜0.05).4)The fermentation broth BCKD activity of 15,30,60 and 120 mg/kg DM thiamine groups was significantly higher than that of 240 mg/kg DM thiamine group(P＜0.05).5)The correlation analysis results showed that the contents of acetate(r=-0.59),butyrate(r=-0.61),isovalerate(r=-0.54)and total volatile fatty acid(r=-0.57)in fermentation broth had a moderate negative correlation with BCFA content(P＜0.05).In conclusion,under in vitro conditions,the thiamine can affect the rumen fermentation characteristics and fatty acid synthesis,and volatile fatty acid content is correlated with BCFA content.The best synthesis effect of BCFA is obtained when the thiamine supplemental level is 60 mg/kg DM.[Chinese Journal of Animal Nutrition,2024,36(8):5141-5151]
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