The objective of this study was to evaluate the genotype-environment interaction (GEI) in the body weight adjusted to 550 days of age (W550) of Polled Nellore cattle raised in Northeastern Brazil using reaction norms (RN) models. Hierarchical RN models included fixed effects for age of cow (linear and quadratic) and random effects for contemporary groups (CG) and additive genetic RN level and slope. Four RN hierarchical models (RNHM) were used. The RNHM2S uses the solutions of contemporary groups estimated by […]

The objective of this study was to evaluate the effect of genotype by environment interaction (GEI) on the weight of Tabapuã cattle at 240 (W240), 365 (W365) and 450 (W450) days of age. In total, 35,732 records of 8,458 Tabapuã animals which were born in the state of Bahia, Brazil, from 1975 to 2001, from 167 sires and 3,707 dams, were used. Two birth seasons were tested as for the environment effect: the dry (D) and rainy (R) ones. The […]

The objective of the present study was to analyze models with genetic and/or residual heteroskedasticity for genetic evaluation of the weaning weight of Charolais-Zebu crossbred calves. Weaning weight data from 56,965 crossbred calves were analyzed using animal models with different combinations of genetic and residual heteroskedasticity and/or homoskedasticity. The inference on a posteriori distributions of genetic parameters were by the Monte Carlo method via Markov chains. The model with genetic and residual heteroskedasticity was the best fit on the data. […]

The objective of this study was to estimate heritability and verify the genetic correlations between heifers subsequent rebreeding with weaning hip height (WHH) and yearling hip height (YHH), using Bayesian inference. The (co)variance components and genetic parameters were estimated using an animal nonlinear (threshold) model for subsequent rebreeding and an animal linear model for WHH and YHH. The animal model included the contemporary group as the systematic effect and direct additive genetic and residual effects as random effects. Genetic maternal […]

Genetic and phenotypic parameters considering the genetic effect on hygienic behavior of queen and workers from 40 Africanized honeybees colonies were estimated separately. Maternal origin of queens was controlled whereas the paternal was unknown, and different groups of workers were considered in three seasons, October 2006, April 2007 and August 2007, but with the same queen. Colonies were 21 honey producers and 19 royal jelly producers. After the method of freezing capped brood, hygienic behavior was determined by the ratio […]

The objectives of this study were to evaluate a multibreed heteroskedastic animal model (MAMR) to estimate residual variance heterogeneity due to breed, heterozigosity, sex and contemporary groups (CG) and robustness to outliers. Differences on variance components, heritability and genetic values estimates were evaluated. It was used 4,016 records of post weaning weight gain (PWG) from Brangus foundation herd of Embrapa Pecuária Sul. Data were analyzed by MAMR with four different residual distribution specifications, which were defined by the nature of […]

It was evaluated statistical models with different assumptions to define the one that best describes the presence of genotype × environment interaction on adjusted post-weaning weight gain (PWG345) of Hereford cattle, through the study of reactions norms to the environment, obtained by random regression using a Bayesian approach. Four reaction norms hierarchical models (RNHM) were used through the INTERGEN program. The RNHMK uses the solutions of contemporary groups previously estimated by the standard animal model (AM) and considers them as […]

The objectives of this study were to use a multibreed animal model to verify the presence of heterogeneity of genetic variance between Angus and Nelore breeds, to verify the importance of the variance due to the segregation between these two breeds and to estimate breed additive genetic effects on the dominance and additive × additive epistatic effects. It was used in this study 4,016 records of post weaning weight gain from Brangus breed foundation herd from Embrapa Pecuária Sul, analyzed […]

Genetic evaluations should become more accurate with the advent of whole genome selection (WGS) based on high density SNP panels. The use of WGS should then accelerate genetic gains for production traits given likely decreases in generation interval due to the greater intent to select more animals based just on their genotypes rather than phenotypes. However, past and current genetic evaluations may not generally connect well to the intended scope of inference. For example, estimating haplotype effects from the data […]

This paper shows the Bayesian approach as an alternative to the classical analysis of nonlinear models for ruminal degradation data. The data set was obtained from a Latin square experimental design, established for testing the ruminal degradation of dry matter, crude protein and fiber in neutral detergent of three silages: elephant grass (Pennisetum purpureum Schum) with bacterial inoculant or enzyme-bacterial inoculant and corn silage (Zea mays L.). The incubation times were 0, 2, 6, 12, 24, 48, 72 and 96 […]