Effects of Yucca on the sheep ruminal fermentation and some serum parameters

In a completely randomized block design experiment, 16 ruminally cannulated male 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, 200or 300 mg/kg diet were fed twice at 8:00 and 16:00 daily. On 15th,16th,and 17th d of experimental period, ruminal content was sampled 0,2,4,6 and 8 h after dosing (8:00), and blood samples were collected at the end of experiment (18th, 19th d).Results showed that acidity was not affected (P=0.13)by YSE. Relative to control, ruminal propionate concentration was increased by YSE addition in a dose-dependent manner by up to 29.8%(P<;0.05),the acetic concentration was decreased by up to 17.5%(P <;0.05). Ruminal ammonia concentration in the first 2 h after feeding was larger (P<;0.05) in sheep receiving no YSE (increased by 17.57 mg/100ml) than in those receiving 200mg/kg (6.77 mg/100ml increase in NH3) or 300mg/kg (6.50 mg/100ml increase). Protozoal populations in the rumen were lower (P<;0.05)with YSE of 300 mg/kg than without. the serum traits of four groups did not differ(P>;0.05)and were within normal physiological range for sheep after feeding 19d.The study indicate that 200 and 300 mg/kg YSE groups have a particular suppressing effect on ruminal ammonia concentration, ammonia N concentrations and protozoal populations were decreased, The effect of YSE on ruminal fermentation was probably a result of a selective inhibitory effect on rumen microbial species. High level (300mg/kg)YSE as feed additives was safely to sheep.