Effects of fractions containing saponins from Yucca schidigera, Quillaja saponaria, and Acacia auriculoformis on rumen fermentation

Fractions containing saponins from Yucca schidigera, Quillaja saponaria, and Acacia auriculoformis on incubation in an in vitro rumen fermentation system containing hay as a substrate increased the efficiency of microbial protein synthesis as judged by (i) a gravimetric approach, (ii) N-15 incorporation into microbial protein, and (iii) purine levels in microbes. The true degradability of hay at 24 h of incubation was either not affected or increased by saponins, and the gas production, which is a measure of short-chain fatty acids and fermentative gases, was lower or similar. Yucca and Quillaja saponins decreased the rate of gas production when hay or a mixture of hay and concentrate (70:30) was used as substrate, but Acacia saponins increased the rate of gas production from the hay plus concentrate mixture. The potential extent of gas production from both of the substrates was lower in the presence of Acacia saponins. Yucca saponins also decreased the potential extent of gas production, but the decrease was lower compared to Acacia saponins. Ammonia levels and protozoal counts at 24 h in an in vitro rumen fermentation system were also reduced by saponins; the decreases were as high as 30 and 63%, respectively.