Assessment of probiotic effects of isolated Megasphaera elsdenii strains in Mehraban sheep and Holstein lactating cows

This study was aimed to evaluate the potential of lactic acid utilizing bacteria in controlling ruminal acidosis in vitro in sheep and their effect as direct fed microbial in dairy cow nutrition. In first in vitro trial, effects of four isolates of Megasphaera elsdenii (SA1, SA2, SA3 and SA4) that were isolated from rumen of Holstein cows were examined on decrease of lactic acid and control of pH in a mixed culture of sheep rumen microorganisms. Gas production, pH, lactic acid and volatile fatty acid for each sample were measured. All isolates decreased lactic acid concentration and increased gas production, but lowest concentration of lactic acid and highest concentration of acetic acid was observed with SA3. In second in vitro experiment, the SA3 isolate was selected and its effect on low or high concentrate feed was evaluated. The trial consisted of four treatments: 1) low forage diet; 2) low forage diet and inoculated with SA3 bacteria; 3) high forage diet; 4) high forage diet and inoculated with SA3 bacteria. Results showed that bacteria inoculation increased gas production and pH and decreased lactic acid concentration. In next stage of study, the effect of the M. elsdenii SA3 isolate was evaluated as a direct fed microbial in dairy cows. Sixteen Holstein dairy cows were used in a completely randomized design of two treatments and eight replicates. The control group received no inoculations and the M. elsdenii treatment were orally inoculated three times with 300 ml ((-)5 x 10(8) cfu/ml) of the SA3 medium on days 0, 10 and 20. Results showed that rumen lactic acid concentration, and also partial pressure of CO2 and total CO2 were significantly lower in M. elsdenii group compared to control. Plasma lactate dehydrogenase was also lower in the M. elsdenii group than control. Milk fat tended to increase in M elsdenii group, this difference was not significant In general M. elsdenii SA3 improved some parameters which can help cows to better cope with ruminal acidosis.