Impact of ground soybean and starch levels on the quality of meat from feedlot young Nellore bulls

- The inclusion of lipid sources in cattle feed may modify the fatty acid profile of the beef.
- The diet containing ground soybean increased polyunsaturated fatty acid.
- High-starch diets decreased saturated fatty acids in the meat from young Nellore bulls.
- C16 and C18 Δ9-desaturase enzyme activities were greater in the muscle from animals fed without ground soybean.
- A lower atherogenicity index was observed in the muscle from animals fed with ground soybean.

Twenty-eight young Nellore bulls (395 ± 32 kg initial body weight) were assigned to a completely randomized design (2 × 2 factorial design with 7 animals per treatment) to evaluate effects on the quality of meat. Diet treatments consisted of high (about 25%) or low (about 16%) starch levels, with or without ground soybean addition. Shear force was decreased in the meat from animals fed a low-starch diet (P = 0.0016). Meat from animals fed a high-starch diet had increased total concentrations of unsaturated (P = 0.0029) and monounsaturated fatty acids (P = 0.0253). Polyunsaturated fatty acid content increased in the meat from animals fed a diet containing soybean (P = 0.0121). High starch diets (> 25%) decreased the concentration of saturated fatty acids and increased the amount of unsaturated fatty acids in the meat from young Nellore bulls.