Effect of salinomycin on in vitro caecal fermentation in pigs

The effect of salinomycin was investigated in anaerobic incubations of the pig caecal contents collected at slaughter, diluted with buffer and either supplied with starch or nor. Salinomycin was present in cultures at 0, 2, 5 and 10 mg/l. In the whole range of concentrations that were tested, salinomycin significantly increased the production of propionate at the expense of acetate and butyrate. At 5 and 10 mg/l, these fermentation shifts were accompanied by a significant decrease of the total VFA, gas and methane production. The formation of molecular hydrogen which was low in control incubations without substrate (0.20 mmol/l), was increased in the salinomycin-treated cultures with starch (1.30 mmol/l). Salinomycin tended to decrease the synthesis of microbial protein, bur its effect was not significant. The metabolic hydrogen recovery was significantly increased in salinomycin-treated cultures, indicating a partial inhibition of acetate formation from CO2 and H-2.