Technical Abstract: Data reviewed in this manuscript describes refined glycerin as a colorless, viscous liquid, containing approximately 99% glycerin; and a metabolizable energy per kilogram of approximately 3,850 and 3,700 kcal for swine and poultry, respectively. Crude glycerin co-product generated from biodiesel production facilities, in contrast, ranges in color from light amber to dark brown, and contains 70 to 90% glycerin, 10 to 20% water, 0 to 7% ash, 0 to 0.3% free fatty acids, and 0.005 to 0.150% methanol, averaging of approximately 85% glycerin, 10% water, and 3% ash with trace amounts of free fatty acids and methanol. In summarization of the literature, the metabolizable energy concentration of crude glycerin is approximately 3,200 in swine and 3,600 in poultry, but varies widely depending upon its composition and inclusion level. Consequently, crude glycerin is an excellent source of calories for nonruminants. Summarization of feeding studies in swine and poultry have shown that supplementation of up to 10% crude glycerin in the diet has no impact on animal performance, carcass composition; or egg and meat quality. However, due to minute levels of methanol and sodium- or potassium chloride, and some potential impacts on feed handling and manufacturing characteristics, inclusion levels may need to be adjusted to prevent any potential metabolic or manufacturing concerns.