Study of the effect of genotype–environment interaction on age at first calving and production traits in Nellore cattle using multi‐trait reaction norms and Bayesian inference

Abstract

This study investigated the effects of genotype-environment interaction on yearling weight, age at first calving and post-weaning weight gain in Nellore cattle using multi-trait reaction norm models. The environmental gradient was defined as a function of the mean yearling weight of the contemporary groups. A first-order random regression sire model with four classes of residual variance was used in the analyses and Bayesian methods were applied to estimate the (co)variance components. The heritability estimates ranged from 0.284 to 0.547, 0.222 to 0.316 and 0.256 to 0.522 for yearling weight, age at first calving and post-weaning weight gain, respectively. The lowest genetic correlations between environment groups for each trait were 0.38, 0.02 and 0.04 for yearling weight, age at first calving and post-weaning weight gain, respectively. Differences in the correlation estimates were observed between traits in the same environments, with the magnitude of the estimates tending toward zero as the environment improved. The results highlight the importance of including genotype-environment interactions in genetic evaluation programs considering the differences observed between environmental groups not only in terms of heritability, but also of genetic correlations.

Genomic reaction norm models exploiting genotype × environment interaction on sexual precocity indicator traits in Nellore cattle

“…Notably, the sexual precocity indicator traits (SC and HP) exhibited significant changes in the mean and genetic variation according to EC levels and animal selection should be carefully assessed. The findings of the present study showed similar trends to those reported in studies for reproductive traits (Santana et al ; Araujo Neto et al ), indicating that G×E interaction significantly affects animal re‐ranking across environmental conditions.…”

Genotype–environment interaction for age at first calving in buffaloes, using the reaction norm model

“…The estimates of genetic correlations between the level and the slope showed moderate magnitudes for the environmental gradient evaluated (Table ), indicating re‐ranking of breeding values in different environments (Santana Júnior et al, ). For AFC this parameter, it has presented a great variability in the literature, being the estimated value similar to those described by Araujo Neto et al () in Nellore cattle (0.45), but with lower value than 0.90, as obtained by Ambrosini et al ().…”

“…Among the several methodologies developed for the study of GEI, reaction norms have been frequently used in studies with productive traits in cattle and buffaloes (Pegolo, Oliveira, Albuquerque, Bezerra, & Lôbo, ; Cardoso & Tempelman, ; Ribeiro et al, ; Rodrigues, Carneiro, Ramos, Ambrosini, & Malhado, ). In relation to reproductive traits, several studies of AFC have reported the GEI effect in cattle (Ambrosini, Malhado, Martins, Cardoso, & Carneiro, ; Araujo Neto et al, ), but no work has been described on buffaloes until now. This study was carried out with the objective to assess GEI in relation to AFC in buffaloes using the reaction norm model and different environmental gradient definitions.…”

Modelos de norma de reação para estudo da interação genótipo × ambiente em rebanhos da raça Nelore

“…These trends corroborate the findings reported by . In the NeT line, null correlation indicated possible reclassification of animals in different environments, corroborating the findings of Ribeiro et al (2017) and Araújo Neto et al (2018). Regarding reproduction-related traits of the NeC and NeS lines, while the correlations between intercept and slope of reaction norms were positive for SC, these were negative for DFC.…”