Probiotic control of lactate accumulation in acutely grain-fed sheep

Abstract

When sheep were acutely fed a grain diet, ruminal pH rapidly dropped to less than 5.0, lactic acid exceeded 100 mM and clinical symptoms of acidosis were evident within 24 h. When acute grain feeding was preceeded by inoculation of the rumen with 108 cfu of Selenomonas ruminantium subsp. lactilytica strain JDB201, ruminal lactate was undetectable and ruminal pH was stabilized at 6.3-6.5 for up to 24 h. Inoculation of the rumen with a mixture of 108 cfu each of Selenomonas ruminantium subsp. lactilytica strain JDB201 and Megasphaera elsdenii strain JDB301 was shown to be more effective than Selenomonas ruminantium subsp. lactilytica alone and maintained ruminal stability following acute grain feeding for up to 4 days. A continuous culture model of acidosis was also developed to test the effect of probiotic inoculation in combination with 0.75 8g/mL of Virginiamycin in preventing lactate accumulation and establishing a stable fermentation in vitro. The data suggest that although probiotic treatment is effective, a combination of probiotic and antibiotic may be the best approach to achieve rapid ruminal adaptation during acute grain feeding of sheep.