Effect of Nigella sativa L. as Saponin Sources on In vitro Rumen Fermentation, Enzyme Activity and Nutrients Digestibility

The effect of Nigella sativa L. as saponin sources on in vitro rumen fermentation, enzyme activity, and nutrients digestibility was investigated in this study. The diet consisted of 70 Napier Grass (Pennisetum purpureum) and 30 wheat pollard containing 0, 0.2, 0.4, and 0.6 saponin, respectively. In vitro fermentation was conducted using Menke and Steingass gas production and two-stage Tilley and Terry. The acquired data were subjected to variance analysis and Duncan’s Multiple Range Test (DMRT). The addition of Nigella sativa L. meal significantly decreases (P<0.05) methane (digested organic matter), protozoa population, and increased microbial protein but does not affect (P>0.05) pH, ammonia concentration, and volatile fatty acids (VFA) production. CMCase enzyme activity reduced (P<0.05) as saponin levels increased, but amylase and protein of enzyme were unaffected (P>0.05). Saponin reduced protein digestibility in the rumen, but there was no difference in dry matter (DM) or organic matter (OM) when compared to the control (P>0.05). Post-rumen nutrients digestibility did not affect by the saponin diet (P>0.05). In conclusion, saponins reduced protozoa population, CH4 production, increased microbial protein, and improve rumen protein digestibility. Therefore, we recommend the use of 0.4 saponins Nigella sativa L. to reduce CH4 production without affecting rumen fermentation.