Effects of dietary energy content and source using by-products on carcass and meat quality traits of cull ewes

ABSTRACT: In cull ewes, energy supply by time short periods can affect growth, carcass traits, and meat quality. The objective of this study was to evaluate the effect of biscuit bran (BB) and cashew nut bran (CNB) in diets with different total digestible nutrient (TDN) content on animal performance and carcass and meat traits of cull ewes. Twenty Morada Nova cull ewes, with the initial BW of 30.1 ± 3.56 kg, and three years of age were distributed in a completely randomized design into factorial scheme 2 × 2, with two energy sources (BB and CNB) × two levels of TDN. All diets were isoproteic with variations in TDN content increased by 10% (TDN10) and 25% (TDN25) above the recommended requirement for the study category, which was 66.0% TDN. The experimental period lasted 56 days, in which daily intake in relation to metabolic weight and weight performance of the animals was determined. The hot carcass, the cold carcass, commercial cuts, loin eye area, and subcutaneous fat thickness were measured, obtained, or calculated. A sample of the Longissimus lumborum (LL) muscle was used by determination of physical–chemical composition, sensory, and fatty acid (FA) profile analysis. The ANOVA was performed to access the effect of diet and energy level on the characteristics studied, and means were compared by the Turkey and Kruskal Wallis tests at 5% of probability. A higher daily gain weight was observed from TDN25 (P = 0.006). Among by-products, higher nutrient intakes were observed in animals fed with BB diets (P < 0.01), except for crude protein. The same patterns have been observed for live weight, reconstituted half-carcass, higher yield in fat thickness, and internal carcass length. Cashew nut bran produced darker colored meat (P = 0.017) and higher cooking weight loss (P = 0.008). Higher lipid content was observed in animals submitted to diets with CNB and TDN25 (P = 0.001). The internal length of the carcass was higher in animals fed with BB (P = 0.041). All diets did not effect on sensory characteristics (P > 0.05). Total digestible nutrient in 25% above recommended promotes higher weight gain and meat with higher lipid content and less weight loss by cooling. The inclusion of BB, compared to CNB, provides a higher weight of carcasses and better conformation, in addition to lower total lipid content with higher proportion for monounsaturated FAs in meat, providing more attractive features for the consumer market.