Effect of α-ketoglutaric acid on in vitro gas production, ruminal fermentation, and bacterial diversity

Effects of different inclusion levels of α-ketoglutaric acid (AKG; 0, 4, 8, and 12 mM) on gas production, ruminal microorganism fermentation and bacterial diversity were evaluated after 72 h in vitro incubations with buffered rumen fluid and wheat straw. Our results showed that the asymptote increased in a linear trend, while the lag time decreased linearly with higher AKG concentrations (P<0.01). The final pH decreased linearly with increasing doses of AKG (P<0.01), while acetate, propionate, butyrate, total VFA yield, and the ratio of acetate to propionate, VFA utilization index, and fermentative CO2 and CH4 produced all increased linearly with increasing of AKG concentration (P<0.05). There was a curvilinear increase in the DMD, NDFD, and IVTD (P<0.05); DMD, NDFD and IVTD were maximal at 4 mM AKG but dropped at high initial AKG doses (P≤0.05). The bacterial community structure changed when AKG was introduced. The results suggest that low concentrations of AKG (4 mM) allow more efficient fiber degradability during in vitro ruminal fermentation of wheat straw, as indicated by higher substrate degradation.