PSXI-29 Effects of Vitamin B6 supplementation on rumen fermentation and branched chain fatty acids content in vitro

Abstract Vitamin B6 promotes branched-chain amino acid aminotransferases in branched chain fatty acids (BCFA) synthesis pathways. This study aimed to investigate the effects of Vitamin B6 supplementation in total mixed ration on rumen fermentation characteristics and the rumen BCFA content in vitro. Treatments were set as dose response with 0, 3, 6, 12 and 24 mg/kg dry matter (DM) Vitamin B6. Each incubated with 75 mL of buffered rumen fluid and 0.5 g of fermentation substrate for 24 h at 39°C. Five replicate parallel fermentation flasks were prepared by each level of supplemented Vitamin B6, and incubation was repeated twice. Filtered fluid with Nylon bags were collected from each fermentation flask. The contents of volatile fatty acids (VFA) and BCFA were determined using an Agilent 6890N GC equipped with a flame ionization detector. All data were analyzed using the linear mixed model of nlme Package in R (version 4.3.1). Compared with the control group, the concentration of total branched chain volatile fatty acids, propionic acid, butyric acid, valeric acid, isobutyric acid and isovaleric acid at 3 mg/kg DM Vitamin B6 significantly decreased, while the ratio of acetic acid to propionic acid was significantly increased (P < 0.01). As the dose of Vitamin B6 increased, the concentrations of iso-C14:0, iso-C15:0, anteiso-C17:0 changed quadratically with greatest at 3 mg/kg DM Vitamin B6 (P < 0.05). Compared with the control group, the contents of iso-C13:0, iso-C14:0, iso-C15:0, anteiso-C15:0, anteiso-C17:0, iso, anteiso and BCFA at 3 mg/kg DM Vitamin B6 significantly increased (P < 0.01). The contents of total iso, anteiso and BCFA increased by 18.80 %, 35.37 % and 22.58 %, respectively, compared with the control. In summary, the results of this study indicated that 3 mg/kg DM Vitamin B6 had beneficial effects on increasing BCFA content than other groups.