EFFECTS OF ALFALFA ROOT SAPONINS ON DIGESTIVE FUNCTION IN SHEEP

The effects of alfalfa saponins on ruminal pH and VFA concentrations, protozoal numbers, forestomach motility, and digesta flow from the rum en were examined in this experiment. In a preliminary study, either 80 0 or 1600 mg/kg of saponins per kg BW were administered intraruminally in a single dose to one of two 60-kg wethers. Ruminal contractions we re suppressed within 15 min. The study was terminated when one wether didn't recover. Saponins were then administered intraruminally in two equal doses daily into four ruminally and duodenally cannulated wether s (60 +/- 1 kg) in amounts equivalent to 0, 200, 400, and 800 mg/kg BW daily in a 4 x 4 Latin Square arrangement. Saponins increased VFA con centrations (P = .001) and lowered ruminal pH (P = .001) after 2 d of administration. On d 2 and d 14, saponins decreased (P < .01) protozoa l populations. On d 11, pressure changes during ruminal contractions i ncreased by 79% during resting (P = .06), 202% during feeding (P = .05 ), and 53% during an 8-h period (P = .08) as the level of saponins inc reased from 0 to 800 mg/kg BW. Administered saponins increased duodena l flows of OM and total N by 19 and 26%, respectively (P = .04 and .01 ). Apparent total tract N digestibility was reduced (P = .02) by 5% at the highest saponin dosage. We conclude that alfalfa may contain enou gh saponins to adversely impact ruminoreticular motility. Saponins als o caused decreased ruminal protozoal populations, increased flow of to tal duodenal N, and reduced ruminal and total tract apparent digestibi lities.