Effects of Megasphaera elsdenii supplementation on fermentation and lactic acid concentration in the rumen: A meta-analysis of in vivo experiments

Abstract

This study evaluated the effects of supplementation M. elsdenii on rumen fermentation and lactic acid concentration in vivo by integrating data from various related studies using a meta-analysis. A database was developed by integrating data from 72 treatments that originated from 17 articles. The parameters integrated were lactic acid concentration, fermentation products, and rumen microbial population. The database compiled was statistically analyzed using a mixed model methodology. Different studies were considered as random effects, and the doses of M. elsdenii were treated as fixed effects. The significance of an effect was stated when its p-value was <0.05. Results showed that supplementation of M. elsdenii linearly reduced lactic acid concentration (P=0.048), proportion of acetate (P=0.045), acetate: propionate ratio (P=0.043) and methane production (P<0.01). In addition, M. elsdenii supplementation also had a significant quadratic effect to increase total VFA (P<0.01) and linearly with pH (P<0.01), proportion of propionate (P=0.037), and valerate proportion (P=0.037). However, supplementation of M. elsdenii did not significantly affect (P>0.05) isobutyrate, isovalerate proportion, and protozoa population in the rumen. It can be concluded that M. elsdenii supplementation is proven to reduce lactic acid concentration, maintain rumen pH, reduce methane production and increase some rumen fermentation products.