Efectos raciales y heterosis materna Criollo-Guzerat para crecimiento posdestete y características de la canal

Abstract

Records from 52 calves born in Nayarit, Mexico, were used to evaluate breed effects and Criollo-Guzerat maternal heterosis (MH) on feedlot performance and carcass traits. Progeny was born from Angus sires and Criollo (C, n=8), Guzerat (G, n=20), Criollo- Guzerat (CG, n=18), and Guzerat-Criollo (GC, n=6) cows. Response variables were initial weight (PIP), yearling weight (PAE), final weight (PEFIP), average daily gain (GADIP), feed efficiency (EFALI), rib eye (AOC), rib fat thickness (GRC), hot carcass weight (PCC), dressing percentage (PRC), kidney and pelvic fat (RP), yield grade (GR), cutability (RC), and retail yield (PTC). Analyses were carried out with the GLM procedure of SAS. Statistical Models for PIP, PAE, PEFIP, GADIP and EFALI included the fixed effects of sex of calf (S), year of trial, breed of sire of the cow (R1) and breed of dam of the cow (R2). Fixed effects fitted to models for AOC, GRC, PCC, PRC, RP, GR, RC y PTC were S, R1 and R2. Grandpaternal differences for breed effects were favorable (P<0.10) to Guzerat for PIP (29.6+8.6 kg), PAE (44.6+11.9 kg), PEFIP (41.0+13.7 kg), AOC 2.25+.47 inches2), PCC (46.58+11.0) and PRC (3.15+.83 %). Grandmaternal differences for breed effects were favorable (P<0.10) to Criollo for EFALI (0.01+.004 kg), AOC (2.20+.61 inches2) and PCC (39.02+14.4 kg). HM was important (P<0.10) for AOC (1.18+.47 inches2) and RP (-3.88+0.99 kg). Grandpaternal and grandmaternal differences for breed effects suggest that GC cows are better than CG cows to produce calves for feedlot in Nayarit.