Influence of tannin concentration in ration on fermentation parameters of Rumen Simulation Technique (RUSITEC): a meta -analysis

Abstract

The objective of this study was to summarize and to quantify the effects of tannin on fermentation parameters of rumen simulation technique (RUSITEe) through a meta-analysis approach. Experiments reporting tannin concentration and rumen fermentation using the RUSITEC system were integrated into a database, and comprised of 6 studies and 2') treatments. Parameters recorded were nutrient digestibility, gas production, methane (CH4) emission, short-chain fatty acid (SCFA) profiles, pH, ar;ul10nia (I'JH3) and microbial population (bacteria and protozoa). The analysis of the data assembled in the database was based on mixed model methodology in which different studies were treated as random effects whereas tannin concentration was treated as fixed effects. Results revealed that in vitro crude protein digestibility (CPD), neutral detergent fiber digestibility (NDFD) and acid detergent fiber digestibility (AGFD) decreased linearly as the tannin concentration increased with the P-value of 0.047, 0.005 and 0.004, respectively. Comparing the magnitude ofreduction in CP and fiber digestibility by the influence of tannin, the compound appeared to cause higher negati ve effect on CP digestibility than that of fi ber as indicated by the slopes. However, the overall OMD did not significantly decrease although the slope remained negative. Methane emission tended to decrease at higher tannin concentration when expressed per unit of substrate (P=0.066) and significantly decreased when expressed per unit of total gas produced (P=0.005). It can be concluded that tannin is a potential compound for mitigating ruminal methane eynission but its use on the other hand also decrease nutrient digestibility.