A companion 84 day feeding study was carried out to analyze the effect of crude glycerin on blood concentrations of the enzymes, glucose and creatinine metabolites. Forty-four Red Norte bulls were fed diets consisting of 30% corn silage, 12% soybean meal, 56% ground corn grain and 2% mineral mixture. Crude glycerin (0, 6, 12 and 18% of the diet’s dry matter) was added to partially replace corn and corn gluten meal was added to maintain the diets isonitrogenous. Blood samples were collected on day 84 of the experimental period, after 16 hours of overnight fasting. The researchers analyzed the blood for several enzymes and metabolites and concluded that feed up to 18% crude glycerin in diet dry matter did not result in health impairment and could be used in commercial feedlot diets.