Bruning C L, Yokoyama M T
Michigan State University, East Lansing 48824-1225.
J Anim Sci. 1988 Feb;66(2):585-91. doi: 10.2527/jas1988.662585x.
The physical and nutritional characteristics of live and killed brewer's yeast slurries and the possible toxicity of intraruminal administration of loading doses of these by-products were evaluated. Dry-matter (DM) percentages of live brewer's yeast slurry ranged from 10.5 to 29.0, and DM percentages of killed brewer's yeast slurry ranged from 14.6 to 18.5. Total crude protein (N X 6.25) percentages of live and killed yeast slurries (DM basis) were 44.1 and 43.1; ethanol percentages (wet basis) were 6.96 and 1.84, respectively. Phase contrast photomicrographs showed distinct differences in morphology between live and killed yeast cells. Intraruminal administration of loading doses (0, 2.3, 4.5 and 6.8 kg) of live and killed brewer's yeast slurries to bull calves induced clinical intoxication at the 4.5-kg and 6.9-kg dosages of live brewer's yeast slurry. No toxicity was induced either with the killed brewer's yeast or with the 0-kg or 2.3-kg dose levels of live brewer's yeast slurry. The clinical signs and plasma ethanol concentrations suggested ethanol intoxication. Ruminal NH3 concentrations increased to over 70 mg/dl with the 4.5-kg and 6.9-kg dosages of live brewer's yeast slurry, but they did not exceed 35 mg/dl with an equivalent dosage of killed brewer's yeast slurry.
对活的和灭活的啤酒酵母浆的物理和营养特性以及瘤胃内给予这些副产品负荷剂量可能产生的毒性进行了评估。活啤酒酵母浆的干物质（DM）百分比范围为10.5%至29.0%，灭活啤酒酵母浆的DM百分比范围为14.6%至18.5%。活酵母浆和灭活酵母浆（以DM计）的总粗蛋白（N×6.25）百分比分别为44.1%和43.1%；乙醇百分比（以湿基计）分别为6.96%和1.84%。相差显微镜照片显示活酵母细胞和灭活酵母细胞在形态上有明显差异。对公牛犊瘤胃内给予活的和灭活的啤酒酵母浆负荷剂量（0、2.3、4.5和6.8千克），活啤酒酵母浆剂量为4.5千克和6.9千克时会引起临床中毒。灭活啤酒酵母以及活啤酒酵母浆0千克或2.3千克剂量水平均未诱发毒性。临床症状和血浆乙醇浓度提示乙醇中毒。活啤酒酵母浆剂量为4.5千克和6.9千克时，瘤胃NH₃浓度升至70毫克/分升以上，但等量的灭活啤酒酵母浆剂量下，瘤胃NH₃浓度不超过35毫克/分升。
