In vitro methanogenesis, microbial profile and fermentation of green forages with buffalo rumen liquor as influenced by 2-bromoethanesulphonic acid

Abstract

The interaction of fibre degrading microbes and methanogens was studied using two forages, lucerne (Medicago saliva) hay and maize (Zea mays) hay, as substrate and 2-bromoethanesulphonic acid (BES) as an additive in an in vitro gas production test. Gas and methane production (ml/g dry matter) were significantly higher (p<0.05) on lucerne as compared to maize hay. Inclusion of BES in the incubation medium significantly suppressed methane emission irrespective of substrate. The population density of total bacteria, fungi, Ruminococcus flavefaciens and Fibrobacter succinogenes was higher, whereas that of methanogens was lower with maize hay as compared to lucerne as substrate. BES suppressed methanogen population by 7 fold on lucerene and by 8.5 fold on maize at 24 h incubation as estimated by real time-PCR. This suppression was accompanied by almost complete (>98% of control) inhibition of methanogenesis. The proportion of acetate decreased, whereas that of propionate increased significantly by inclusion of BES, resulting in narrowing of acetate to propionate ratio. In vitro true digestibility (IVTD) of lucerne was significantly higher as compared to maize but BES inclusion did not affect IVTD.