Reaction norms of direct and maternal effects for weight at 205 days in Polled Nellore cattle in north-eastern Brazil

Abstract

Abstract. This study investigated the presence of genotype-environment interaction (GEI) for body weight adjusted to 205 days of age (W205) in Polled Nellore cattle raised in north-eastern Brazil using reaction norm (RN) models. The reaction norm hierarchical models (RNHM) included the fixed (linear and quadratic) effect of cow’s age, random effect of contemporary group (CG), RN level and slope for additive direct and maternal genetic effects and permanent maternal environmental effect. The one-step reaction norm model with homogeneous residual variance (RNHM1sHm) yielded the best adjustment compared to the others. Based on this model, the estimates of direct additive and maternal variances and increased with environment improvement (35.34±7.92 kg2 to 134.42±25.97 kg2 and 12.76±5.38 kg2 to 58.22±19.74 kg2 for low and high-quality environments, respectively). The estimates of heritability direct additive and maternal too increased with environmental improvement (0.08±0.02 to 0.24±0.04 and 0.03±0.01 to 0.10±0.04). The correlation between the intercept and the slope of RNHM indicates that animals with higher genetic values respond more efficiently to environmental improvements, representing a scale effect for W205. These results allowed us to characterize the GEI for W205 and showed that specific evaluation should be performed with low, intermediary and high production levels.

Heteroscedastic Reaction Norm Models Improve the Assessment of Genotype by Environment Interaction for Growth, Reproductive, and Visual Score Traits in Nellore Cattle

“…For weaning traits and visual scores at yearling, the linear reaction norm models presented the best fit, suggesting that the animals present a single pattern of sensitivity along the environmental gradient. Ambrosini et al [ 27 ], also observed that for weaning weight in Nellore cattle, the homoscedastic model outperformed the heteroscedastic model. However, as can be seen in the Table S1 , the animal model surpassed the reaction norm models for WC, WP, and WM according to the AIC criteria, suggesting that there is no presence of GxE for these traits.…”

“…Results obtained in this study illustrated that the heritability estimates varied along the environmental gradient ( Figure 1 , Figure 2 and Figure 3 ), due to variation in additive genetic and residual variance (for heteroscedastic models) as a function of the environmental gradient. Heritability estimates varying along EGs were also observed by Ambrosini et al [ 32 ], Chiaia et al [ 3 ], and Ribeiro et al [ 33 ] for YW in Nellore cattle; by Chiaia et al [ 3 ], Lemos et al [ 34 ], and Mota et al [ 12 ] for SC in Nellore cattle; by Chiaia et al [ 3 ], Lemos et al [ 34 ], and Araujo Neto et al [ 4 ] for AFC in Nellore cattle; by Carvalheiro et al [ 9 ] for adjusted weight gain from weaning to yearling in Nellore cattle; by Cardoso and Tempelman [ 35 ] for post-weaning weight gain in Hereford cattle; by Macneil, Cardoso, and Hay [ 36 ] for preweaning gain in Hereford cattle; and by Ambrosini et al [ 27 ] for weaning weight in Nellore cattle.…”

Genotype by environment interactions for body weight in Mediterranean buffaloes using reaction norm models

“…Before 2004 genetic evaluations for Mediterranean buffaloes did not exist in Brazil.With the release of information based on the BLUP (best linear predictors not addicted) methodology in 2004, genetic values of Brazilian buffalo have been predicted and sire selection has started to be based on this criterion. However, as the usual genetic evaluation does not consider GxE, the gains may be lower than expected, especially in production environments with lower-level management Ambrosini et al (2014). in cattle have not reported a significant change in classification when comparing the low, medium and high levels of HRNM1s.…”

Interação genótipo x ambiente para peso aos 365 dias em bubalinos da raça Mediterrâneo

“…,Mattar et al (2011) eAmbrosini et al (2014), que avaliaram o ganho de peso padronizado pós-desmama, para as raças Angus, Devon, Hereford, Canchim e Nelore, respectivamente. Os parâmetros e valores genéticos são estimados de forma conjunta e simultânea pelo MHNRHO 1P .…”