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Context: Crude glycerin (CG) is an energetic byproduct that generates glycerol, an energy product that is absorbed by the ruminal wall and conducted to the liver, where it is metabolised and it is converted to glucose, by the action of the enzyme glycerol kinase, in a gluconeogenesis process. Aims: The study objective was to determine the effect of CG inclusion, replacing corn bran, in a total mixed ration to lambs, on carcass traits, physicochemical properties and the fatty acid (FA) profile of lamb meat. Methods: Forty-four uncastrated crossbred Santa Ines × indigenous lambs were distributed in a completely randomised study, with four CG inclusion levels (0, 70, 140 and 210 g/kg in the lamb diet). Key results: The addition of CG up to a level of 70 g/kg to the lamb diets promoted greater slaughter bodyweight, hot and cold carcass weight, carcass traits, and meat lipid content, and improved Warner–Bratzler shear force in meat. Inclusion of CG in the diet did not affect (P > 0.05) the pH and colour parameters (lightness, redness, yellowness and chroma) of meat. The FA composition of the longissimus lumborum of lambs C14:0, C15:1, C16:0, C18:1 cis and ΣFA medium-chain were greater, and FA meat concentration of C14:1, C15:0, C17:1, C18:0, C18:2 n −3, C18:2 n −6, ΣPUFA, ΣFA-old-chain and elongase enzymatic activity were lower in lambs fed without CG and with 70 g/kg CG, compared with lambs mainly fed 140 and 210 g/kg CG. The heath indexes, atherogenicity index and desirable FAs improved by dietary CG inclusion of 210 g/kg to the diet of lambs. Conclusions: CG obtained from biodiesel production can be incorporated in lamb diets up to 70 g/kg total mixed ration, replacing corn bran to improve the weight gain, meat lipid content, Warner–Bratzler shear force and FA profile of lamb meat. Meat fat-related consumers health indices improved from the biggest inclusions of CG to the diet of lambs However, the use of CG at levels 140 and 210 g/kg total mixed ration reduces the performance, carcass weight and morphometric measurements. Implications: It is recommended the inclusion at a maximum level of 70 g of CG/kg DM as total mixed ration replacing corn bran improves the weight gain, cooking weight loss, Warner–Bratzler shear force, meat lipid content and consequently FA meat composition. Crude glycerin is a byproduct of biodiesel production that can be used in the diets of ruminants to replace corn bran, because it has the potential to be a gluconeogenic and, therefore, energetic substrate. Enhancing the diet's energy density may improve the performance of animals, increasing the carcass fat content and thereby improving the physicochemical composition. Meat parameters, such as colour and shear force, generally represent the appearance, sensory traits and fatty acid profile of lamb meat. Other parameters can predict the meat acceptance by the consumer market. [ABSTRACT FROM AUTHOR]