In vitro evaluation of dose-response effects of salinomycin antibiotic on rumen fermentation and some rumen microorganisms using Real-time PCR

The present study was conducted to assess the effects of salinomycin antibiotic at different doses (0, 2, 4, 8 and 16 mg/L) on gas production kinetics, some rumen digestion and fermentation indices, and at the doses of 0, 4 and 16 mg/L on some rumen microbial populations using Real-time PCR method. For this purpose, three ruminally fistulated male rams were used to collect the rumen fluid for incubations of 144 h in the first and incubations of 24 h in the second phase of the experiment. Results indicated that the gas produced at all the measured times and the asymptotic gas production (A) increased linearly and quadratically with increasing doses of salinomycin. However, the gas production rate (µ) was not affected by the treatment. The gas produced after 24 h of incubation (GP24), in vitro true dry matter degradability (IVTDMD), in vitro true organic matter degradability (IVTOMD) and total volatile fatty acid (TVFA) concentration increased in a linear and quadratic manner, but partitioning factor (PF) decreased and microbial biomass (MB) and ammonia concentration were not affected by salinomycin. Among the rumen microorganisms, the relative population of protozoa and Fibrobacter succinogens decreased at the highest dose of salinomycin and those of fungi, methanogens and Clostridium aminophilum remained unaffected by salinomycin. These results revealed that salinomycin has a positive impact on rumen digestion and fermentation indices, which regarding recent findings on its effects in preventing different kinds of human cancer, it can be used as feed additive in animal nutrition.