Heritability and factors affecting growth traits and age at first calving of zebu beef heifers in South-Eastern Mexico

Abstract

Information for this study was obtained from a commercial beef enterprise located in the subhumid tropics of Yucatan, Mexico. Data from 664 females of different zebu breeds born from 1972 to 1983 were considered for analyses. Weaning and 18-month weights were adjusted to 240 (W240) and to 550 (W550) days of age, respectively. The statistical model included the fixed effects of years of birth, season of birth, age of dam at calving, breed of heifer and the random effect of sire within breed. Arithmetic mean +/- standard deviations were 32.1 +/- 3.6 kg, 208.3 +/- 29.1 kg, 678.1 +/- 94.6 g, 308.7 +/- 29.7 kg, 342.3 +/- 89.8 g and 1,060.2 +/- 118.7 days for birth weight (BW), W240, average preweaning daily gain (ADG), W550 postweaning daily gain (PDG) and age at first calving (AFC), respectively. Year and season of birth had significant (P < 0.05) effects on W240, ADG, W550, PDG and AFC. Parity number was significant (P < 0.05) for BW, W240, ADG and AFC. Breed differences were significant (P < 0.01) for all traits, except BW. Guzerat heifers were heavier at weaning and W550 than heifers from the other breeds. Guzerat heifers first calved at an average age of 995 days; Brahman and commercial zebu heifers calved about 50 to 60 days later and the Indubrazil and Gyr heifers about 2 months later still. The heritability estimates were 0.24 +/- 0.13 for BW, 0.26 +/- 0.14 for W240, 0.29 +/- 0.14 for ADG, 0.43 +/- 0.17 for W550, 0.56 +/- 0.20 for PDG and 0.46 +/- 0.15 for AFC.

Genetic parameters and genetic trends for age at first calving and calving interval in an Angus-Blanco Orejinegro-Zebu multibreed cattle population in Colombia

“…Differences in breed composition, management, nutrition, and model used (sire vs. animal model) are likely to have contributed to these differences. The AFC heritability estimate here was higher than one obtained for Nellore cattle in Brazil (0.05; Silveira et al, 2004), but lower than those reported for Brahman-Nellore-Guzerat-Gir multibreed cattle in Mexico (0.46 ± 0.15; Magaña and Segura, 1997), Romosinuano in Costa Rica (0.28 ± 0.16; Casas and Tewolde, 2001), and Brahman in Mexico (0.46 ± 0.14; Estrada-León et al, 2008). However, the AFC heritability was similar to the ones estimated for Canchim in Brazil (0.13; Talhari et al, 2003), and for Romosinuano in Colombia (0.16 ± 0.09; Suárez et al, 2006).…”

Body weights at weaning and 18 months of Zebu, Brown Swiss, Charolais and crossbred heifers in south‐east Mexico

“…1995, 2000). However, Magaña & Segura (1997) in B. indicus breeds, other than B, reported higher mean values in a herd located in the same area as the present study.…”

“…The undefined crossbred group had better WW8 performance than B and similar to BS and CH heifers and BW18 was better than Z and BS but similar to CH and the best crossbred heifers. This could be due to a retained heterosis in the undefined crossbred group as were pointed out in other studies in the same region (Magaña & Segura 1997, 1998).…”

“…Factors such as year and season of birth, parity, sex and breed have been reported to affect body weight of cattle at different ages (Reynoso et al. 1987; Magaña & Segura 1997, 1998). To the authors’ knowledge there are few reports on weaning weight (Hinojosa et al.…”

Genetic parameters for reproductive traits in a beef cattle herd estimated using multitrait analysis

“…Kassab (1995), Singh et al (1996) and Magana & Segura (1997) obtained h 2 values for AFC of 0.46, 0.36 and 0.46, respectively. It therefore seems to be possible to change age at first calving through selection.…”