Parameter estimates for reproductive and carcass traits in Nelore beef cattle

Abstract

The aim of this study was to estimate genetic parameters for scrotal circumference at 365 (SC365) and 450 (SC450) days of age, age at first calving (AFC), ribeye area (REA), backfat (BF) thickness, and rump fat (RF) thickness, in order to provide information on potential traits for Nelore cattle breeding program. Genetic parameters were estimated using the Average Information Restricted Maximum Likelihood method in single- and multitrait analyses. Four different animal models were tested for SC365, SC450, REA, BF, and RF in single-trait analyses. For SC365 and SC450, the maternal genetic effect was statistically significant (P < 0.01) and was included for multitrait analyses. The direct heritability estimates for SC365, SC450, AFC, REA, BF, and RF were equal to 0.31, 0.38, 0.24, 0.32, 0.16, and 0.19, respectively. Maternal heritability for SC365 and SC450 was equal to 0.06 and 0.08, respectively. The highest genetic correlations were found among the scrotal circumferences. Testing for the inclusion of maternal effects in genetic parameters estimation for scrotal circumference should be evaluated in the Nelore breeding program, mostly for correctly ranking the animal's estimated breeding values. Similar heritability estimates were observed for scrotal circumference, as well as favorable genetic correlations of this trait with AFC and carcass traits. Thus, scrotal circumference measured at 365 days of age could be a target trait for consideration in the Nelore selection index in order to improve most of the traits herein analyzed.

Genetic association between different criteria to define sexual precocious heifers with growth, carcass, reproductive and feed efficiency indicator traits in Nellore cattle using genomic information

“…Similar results were reported by Buzanskas et al. () between AFC and RFT (−0.08 ± 0.09) and AFC and REA (−0.12 ± 0.08) traits in Nellore cattle populations. Low genetic correlation estimates between heifer pregnancy and muscling or finishing scores were reported by Shiotsuki et al.…”

“…For carcass traits, heritability obtained for REA was close to those reported by Buzanskas et al. () (0.29 ± 0.03–0.31 ± 0.03). Higher heritability estimates for SFT and RFT were reported by Yokoo et al.…”

“…The mean for SC455 was higher than those reported by Buzanskas et al. (). The same was observed for RFT and SFT, but not for REA (Buzanskas et al., ).…”

“…(). The same was observed for RFT and SFT, but not for REA (Buzanskas et al., ). Based on the results, differences in mean between the studies could be associated with sampling population, because heifers exposed earlier to bulls and related animals were used in the present study.…”

Genetic parameters for fertility traits in Nellore bulls

“…Scrotal circumference (SC) is the main reproductive trait evaluated in males, since it is easy to measure and it is related to sexual precocity (Burns, Gazzola, Holroyd, Crisp, & Mcgowan, ; Buzanskas et al, ). Nevertheless, there is limited knowledge about the genetic correlations among SC and semen quality and other male reproductive traits.…”