Effects of saponin from Biophytum petersianum Klotzsch on ruminal fermentation, microbial protein synthesis and nitrogen utilization in goats

Four Kacang goats were used in a 4 × 4 Latin square experiment to determine effects of saponin from Biophytum petersianum Klotzsch on ruminal fermentation characteristics (i.e., pH, ammonia–N and volatile fatty acids (VFA)), protozoal numbers, microbial protein synthesis and N utilization in goats fed a silage-based diet. The goats were fed twice daily (08:00 and 16:00 h) with a basal diet consisting of elephant grass silage and a grain-based concentrate (70:30 on a dry matter (DM) basis). Treatments consisted of Biophytum aqueous extract administrated orally in amounts of 0 (control), 160, 239 and 319 ml twice daily, corresponding to 0, 13, 19.5 and 26 mg of saponin/kg body weight. Results show that ruminal ammonia–N concentrations decreased linearly (P<0.01) with increasing saponin and pH values, ranging from 6.91 to 7.02, increased linearly (P<0.01) with added saponin. There were linear decreases (P<0.05) of total VFA concentration and proportions of butyrate and iso-acids, as well as protozoal numbers, in response to increased saponin feeding. There were linear decreases in urinary N (P<0.01) and total N excretion (P=0.05) per unit N intake with increased saponin feeding. Retained N as a proportion of N digested and efficiency of microbial N synthesis, increased linearly (P<0.01) in response to saponin feeding. Results indicate that B. petersianum water extract can be used to modify ruminal fermentation in order to increase retained N per unit N digested and reduce total N excretion per unit N intake. This may contribute to mitigating environmental pollution from ruminants.