Fat thickness, conformation, carcass weight, and age on the physical composition and quality of the meat from Nellore cows

The carcasses of cull cows are normally penalized and paid only for their weight and age, without considering muscle expression, subcutaneous fat and marbling. The aim of this study was to analyse the effects of carcass subcutaneous fat thickness (SFT), conformation score, cold carcass weight (CCW), and age on the physical composition of the carcass and the meat quality of 152 Nellore cull cows, aged between 3 and 16 years. The data were submitted to regression analysis by Proc Reg and Proc Stepwise procedures. An increase of 1 kg in CCW and one point in the conformation score resulted in increases of 0.12 kg and 1.70 kg in muscle weight, respectively. SFT and age had a positive effect on the percentage of fatty tissue (0,56 and 0,23%, respectively), and a negative effect on the percentage of muscle tissue (0,47 and 0,23%, respectively). Intramuscular fat increased every 0.11 mm of SFT and every 0.21 points in carcass conformation. The lowest shear force occurred SFT reached 5.6 mm. Meat palatability increased until SFT reached 7.1 mm. Quality of meat from Nellore cows, occurs with increased weight and carcass conformation, reducing age at slaughter and SFT between 5 and 8 mm.