Effect of different levels of added selenium without or with arsenic on rumen fermentation parameters in buffaloes under in vitro conditions

Studies were conducted to find the effect of addition of different levels of selenium (Se) without or with arsenic (As) on rumen fermentation parameters viz., in vitro gas production (IVGP), true organic matter digestibility (TOMD), microbial biomass production (MBP), total volatile fatty acids (TVFA) and individual volatile fatty acids (IVFA) under in vitro conditions. Basal substrate (200 mg) comprising of paddy straw and concentrate mixture (40: 60) alongwith different levels of Se (0, 2, 4, 8, 10, 12 and 14 mu g/200 mg substrate or per syringe) was incubated in 100 ml glass syringes. Arsenic, an antagonist of Se in form of sodium arsenite, was used @ 0, 10, 20, 40, 80 and 100 mu g levels added to the substrate (200 mg). The inhibitory effect on TOMD, IVGP, MBP and TVFA was observed at 12 mu g added Se level. Addition of As at 10 or 20 mu g level to the substrate (200 mg) containing 12 mu g Se improved rumen fermentation parameters under in vitro system, however, further addition of As (40, 80 or 100 mu g) showed negative effects on these parameters.