TEA SAPONIN MODULATES IN-VITRO RUMEN FERMENTATION PROFILE AND REDUCES METHANE PRODUCTION: A META-ANALYSIS

Abstract

Saponins are secondary plant metabolites that bind to hydrophobic non-sugar components which are capable of reducing rumen enteric CPU production. However, the effect of different levels of dietary tea saponin on rumen fermentation remains inconclusive. This study aimed to investigate the effect of tea saponin on in-vitro rumen fermentation and rumen enteric CH4 production through a meta-analysis approach. A total of 6 articles were selected and included in the meta-analysis database, continued by statistical analysis using SAS software by performing mixed model formula. The results showed that tea saponin levels lowered in-vitro organic matter degradability (TVOMD) and in-vitro dried matter degradability (TVDMD; P = 0.01) by a linear response. Furthermore, increased tea saponin levels in the diet reduced enteric CH4 emission expressed as CH4/DM substrate and CH4/IVOMD by a quadratic (P = 0.01) and a linear response (P = 0.04), respectively. Increased tea saponin levels also tended to decrease gas production linearly (P = 0.08). Tea saponins inclusion also decreased pH levels linearly (P = 0.04), but increased NH3 concentration quadratically (P = 0.01). Moreover, the inclusion of tea saponin quadratically increased the total volatile fatty acids (VFA) concentration in the rumen and linearly increased acetate (C2) and propionate (C3) proportions (P < 0.05). As a result, the C2/C3 ratio linearly decreased (P = 0.01) by the increased tea saponin levels, where protozoa population also quadratically diminished (P = 0.01). In conclusion, tea saponin levels directly reduced enteric CH4 production by diminishing protozoa populations.