The effect of heterosis and genetic group on the distribution of internal and trim fat and, external components of the body of purebred, Charolais (C) and Nellore (N), and crossbred steers from second (G2) (¾C ¼N and ¾N ¼C), third (G3) (5/8C 3/8N and 5/8N 3/8C) and fourth (G4) (11/16C 5/16N and 11/16N 5/16C) generations of feedlot finished rotational crossbreeding were evaluated. Steers from G2 showed higher absolute weight for renal, intestinal and total fat when compared to purebreds' average, resulting in heterosis of 39.88, 43.96 and 31.80%, respectively. Ruminal fat of G4 steers was 41.48% higher than purebreds' average. When expressed as percentage of empty body weight (EBW), G2 remained superior to purebreds only for intestinal fat, with heterosis 28.06%. Trim fat expressed per 100 kg of EBW in G4 was 21.67% lower than purebreds' average. Charolais steers had higher absolute trim fat weight when compared to Nellore (2.85 vs 1.30 kg). The ¾C ¼N steers had higher intestinal fat than ¾N ¼C steers, in absolute (10.15 vs 7.83 kg) and relative weight (2.59 vs 2.02%). The 11/16N 5/16C steers showed higher ruminal fat weight when compared to 11/16C 5/16N steers (6.93 vs 4.94 kg). Heterosis for relative head weight was negative and significant in G3 (-15.54%) and G4 (-13.12%), whereas the relative feet weight was only significant in G3 (-11.08%). Relative feet weight of Charolais steers was higher than for Nellore (2.18 vs 1.88%). The carcass non-integrant fats show significant heterosis in the rotational Charolais × Nellore crossbreeding.
Bos indicus; Bos taurus; empty body weight; heterosis; internal fat; renal fat
