Supplementation effects of tannin and saponin extracts to diets with different forage to concentrate ratio on in vitro rumen fermentation and methanogenesis

Abstract

This experiment was aimed to investigate the effect of combining tannin and saponin extracts on ruminal methane emission of diets with different proportion of forage to concentrate in the in vitro fermentation. The experiment was conducted in a factorial block design. The first factor was the proportion of forage:concentate in diets (70:30 and 30:70) and the second was addition of tannin and saponin extracts (control, tannins, saponins, tannins + saponins) in the dose of 2 mg/ml. Variables observed were gas production kinetics, methane production, dry matter digestibility (DMD), organic matter digestibility (OMD) and ammonia concentration. Results revealed that addition of tannins, saponins and their combination generally lowered total gas and methane production during 24 and 48 h of incubation period in both types of diets (P<0.05), but combination of tannins and saponins compared with their separated forms did not show any significant differences. The addition of tannins, saponins and their combination reduced DMD, OMD and ammonia significantly (P<0.05). It can be concluded that the addition of tannin, saponin and their combination at a dose of 2 mg/ml could reduce methane emission but followed by a decline in the DMD, OMD and ammonia.