摘要
In a completely randomized block design experiment, 16 ruminally cannulated sheep （40 ±2.1 kg）fed a 50% concentrate： 50% forage diet （DM basis） were given intraruminal doses of powdered Yucca schidigera extract （YSE）. Doses of 0 （control）, 100, 200, or 300 mg kg^-1 diet were given at 8 p.m. and 4 a.m. On 15, 16, and 17 d of the experimental period, ruminal contents were sampled 0, 2, 4, 6, and 8 h after dosing, and blood samples were collected at the end of the experiment （18th and 19th d）. Acidity was not affected （P〉0.05） by the addition of YSE. Compared with the control, ruminal propionate concentration was increased by 29.4 and 29.8% （P〉 0.05） and the acetic acid concentration was decreased by 15.1 and 19.8% （P〉0.05） at 4 and 6 h after YSE （300 mg kg^-1） dosing, respectively. Ruminal ammonia concentration in the first 2 h after feeding was higher （P〈0.05） in the sheep that did not receive YSE （increased by 17.57 mg 100 mL^-1） than in those that received 200 mg kg^-1（increased by 6.77 mg 100 mL^-1） or 300 mg kg^-1 （increased by 6.50 mg 100 mL^-1） YSE. Protozoan populations in the rumen were lower （P〈0.05） in the animals that received 300 mg kg^-1 of YSE compared with the control. All serum parameters of the four groups were in the normal range and were similar among the treatment groups （P 〉 0.05）, after being fed for 19 d with different doses of YSE. The effect of YSE on ruminal ammonia concentration likely resulted from a decreased concentration of protozoan populations and, presumably, from ammonia binding by YSE.
In a completely randomized block design experiment, 16 ruminally cannulated sheep （40 ±2.1 kg）fed a 50% concentrate： 50% forage diet （DM basis） were given intraruminal doses of powdered Yucca schidigera extract （YSE）. Doses of 0 （control）, 100, 200, or 300 mg kg^-1 diet were given at 8 p.m. and 4 a.m. On 15, 16, and 17 d of the experimental period, ruminal contents were sampled 0, 2, 4, 6, and 8 h after dosing, and blood samples were collected at the end of the experiment （18th and 19th d）. Acidity was not affected （P〉0.05） by the addition of YSE. Compared with the control, ruminal propionate concentration was increased by 29.4 and 29.8% （P〉 0.05） and the acetic acid concentration was decreased by 15.1 and 19.8% （P〉0.05） at 4 and 6 h after YSE （300 mg kg^-1） dosing, respectively. Ruminal ammonia concentration in the first 2 h after feeding was higher （P〈0.05） in the sheep that did not receive YSE （increased by 17.57 mg 100 mL^-1） than in those that received 200 mg kg^-1（increased by 6.77 mg 100 mL^-1） or 300 mg kg^-1 （increased by 6.50 mg 100 mL^-1） YSE. Protozoan populations in the rumen were lower （P〈0.05） in the animals that received 300 mg kg^-1 of YSE compared with the control. All serum parameters of the four groups were in the normal range and were similar among the treatment groups （P 〉 0.05）, after being fed for 19 d with different doses of YSE. The effect of YSE on ruminal ammonia concentration likely resulted from a decreased concentration of protozoan populations and, presumably, from ammonia binding by YSE.
