Research on Yucca schidigera extract feeding on the rumen ecology, protozoal populations and serum chemistries of sheep

In a completely randomized block design experiment, 16 ruminally cannulated male sheep with body weights of (40 ± 2.1) kg were fed twice daily (8:00 and 16:00) with concentrate and forage (50:50 on dry matter (DM) basis). Dietary treatments were supplemented with intraruminal doses of powdered Yucca schidigera extract (YSE) at the levels of 0 (control), 100, 200 and 300 mg · kg⁻¹. On days of 15, 16 and 17 after feeding, ruminal content was sampled at 0, 2, 4, 6 and 8 h after dosing (8:00), and blood samples were collected at the end of experiment (the days 18 and 19 after feeding). Results showed that the treatment groups’ acidity was not affected (P = 0.13) by YSE. Comparing to the control, the ruminal propionate concentration was increased by YSE addition in a dose-dependent manner by up to 29.8% (P < 0.05), and the acetic concentration was decreased by up to 17.5% (P < 0.05). The ruminal ammonia concentration 2 hours after feeding was higher (P < 0.05) in sheep fed without YSE (increased by 17.57 mg· 100 mL⁻¹) than those fed with YSE at 200 mg · kg⁻¹ (6.77 mg · 100 mL⁻¹ increase in NH₃) and at 300 mg · kg⁻¹ (6.50 mg· 100 mL⁻¹ increase in NH₃). Protozoal populations in the rumen were lower (P < 0.05) with the YSE feeding dose at 300 mg · kg⁻¹ than the control. The serum chemistries were not different among treatments (P > 0.05) and were within the normal physiological ranges for sheep 19 days after feeding. The study indicated that 200 mg· kg⁻¹ and 300 mg· kg⁻¹ YSE groups had particular suppressing effects on ruminal ammonia concentration, ammonia-N concentrations and protozoal populations. The effect of YSE on ruminal fermentation could be attributed to the selective inhibitory effect on rumen microbial species. High level (300 mg · kg⁻¹) YSE as feed additives resulted no negative impact on sheep in our tests.