The objective of this trial was to develop simple regression equations for estimating the chemical body composition of Nellore steers by using the chemical composition of the 9-10-11th ribs cut. Twenty-seven feedlot Nellore steers varying from 338.0 to 503.6 kg of BW and from 21 to 31 months of age were used. Six reference animals were slaughtered at the beginning of the trial to estimate the initial chemical body composition. Contents of water, protein, EE, and ash of the 9-10-11th ribs cut and body tissues were determined. Regression equations for estimating empty body weight (EBW) through measurements of BW and hot carcass weight (HCW) were: EBW = 0.8726 LW - 2.7399 and EBW = 1.5350 HCW + 13.598. The high R² values (0.98) in both equations indicated that the EBW of Nellore steers can be predicted by using BW and HCW. The gain of 1.0 kg of EBW corresponded to approximately 1.15 kg of BW. Water content of empty body (EB) was highly correlated with water (R² = 0.98) and EE (R² = 0.91) contents of the ribs cut; the equation based on the percentage of water in the ribs cut had the best fit (Sx, y = 0.46). Because the percentage of EB EE was highly correlated (R² = 0.95) with that of the ribs cut, the equation %EB EE = 0.9662% ribs EE + 1.5294 may be used for estimating EE content of EB. The same was true for ash, which can be estimated by the equation %EB ash = 0.5915% ribs ash + 0.7619 (R² = 0.88). It was concluded that the percentage of water, EE, and ash in the 9-10-11th ribs cut accurately estimated the EB composition of feedlot Nellore steers.
beef cattle; coefficient of determination; empty body; ether extract; protein
