The effect of different doses of Astragalus root extract on in vitro rumen fermentation of steamflaked maize grains used as an only substrate

摘要

An in vitro study was conducted to determine the effect of different doses of Astragalus root extract (ARE, Huangqi) on rumen fermentation of steam-flaked maize grains. Rumen fluid was taken from 3 crossbred steers fed a 55% forage to 45% mixed concentrate ratio diet. As ARE dose was increased, ruminal ammonia-N concentration was decreased in a dose dependent manner, whereas total volatile fatty acid concentration and total gas production were increased linearly (P＜0.001). Increasing ARE doses resulted in decreased molar proportion of acetate and increased molar proportion of propionate as well as a decrease in acetate: propionate ratio. In conclusion, ARE could stimulate the mixed ruminal fermentation as well as modify the pattern of rumen fermentation in vitro.