ABSTRACT This study aimed to evaluate genotype × environment (G×E) interactions in Guzerá breed animals for 305-day first-lactation cumulative yields (kg) of milk (MY305), fat (FY305), and protein (PY305). We used 6823 records of MY305, 2466 records of FY305, and 1870 records of PY305. The contemporary groups (CG) were created considering herd and year of calving. The analyses were performed in two steps. In the first step, environmental effects on phenotypes were estimated by using a multi-trait model ignoring G×E […]

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 […]

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 […]

This study was carried out to evaluate the use of different residual variance structures to estimate covariance functions for weight of Canchim beef cattle. The covariance functions were estimated by the Restricted Maximum Likelihood method, in an animal model with fixed effect of contemporary group (year and month of birth and sex), age of dam at calving as covariable (linear and quadratic effects) and mean growth trajectory while the random effects considered were the direct additive genetic and maternal effects, […]

Data consisting of 2,440 first lactations of Gyr cows calving between 1990 and 2005 were used to estimate genetic parameters of monthly test-day milk yield (TDMY). Records were analyzed by random regression models (MRA) that included the additive genetic and permanent environmental random effects and the contemporary group, age of cow at calving (linear and quadratic components) and the average trend of the population as fixed effects. Random trajectories were fitted by Wilmink’s (WIL) and Ali & Schaeffer’s (AS) parametric […]

Data consisting of 3,531 test day records of 620 first parity Jersey cows were used to estimate genetic parameters for milk yield. Covariance components were estimated by repeatability and random regression animal models. The Wilmink function was used in the random regression model to fit the fixed effect of season of calving and the additive genetic, permanent environment and residual random effects. The repeatability model included the fixed effects of herd-year-month of test, season of calving and age at calving […]

Data comprising 68,523 test day milk yield of 8,536 cows of the Holstein breed, calving from 1996 to 2001, were used to compare random regression models, for estimating variance components. Test day records (TD) were analyzed as multiple traits, considering each TD as a different trait. The test day records were analyzed as longitudinal traits by different random regression models regarding the function used to describe the trajectory of the lactation curve of the animals. The Wilmink’s exponential function, the […]

Data consisting of 9,374 test day milk yield records from 302 first lactations of Alpina goats were analyzed by random regression models using the Wilmink and Ali and Schaeffer functions and Legendre orthogonal polynomials of third and fifth orders. Models including animal additive genetic, permanent environmental and homogeneous or heterogeneous (three or four classes) residual random effects were compared by Akaike information criterion (AIC), Schwarz Bayesian information criterion (BIC), likelihood ratio test (Ln L), phenotypic, permanent environmental, genetic and residual […]

Random regression models using Legendre polynomials were used to describe the growth curve of Nelore cattle weighted every three months from birth to 720 days of age, in Pernambuco state, northeastern Brazil. Six different random regression models using Legendre polynomials of three, four, and five degrees to model additive genetic and permanent environmental effects, under homogeneous and heterogeneous residual variances with three classes were evaluated. According to the Akaike’s information criteria, the five degree Legendre polynomial with homogeneous error was […]

Breeding values were predicted for test day milk yields of Caracu cows, using univariate model (TDMO) and random regression model (RRM). The ranks were based on traditional 305-day milk yield breeding values (PTA305). For RRM, breeding values were predicted for individual test-day milk yield and for sum of all test-days (RRM305). Spearman correlation were estimated among predicted breeding values from different methodos (TDMO and RRM) and the coincidence of rank of 10% best sires were verified. Genetic lactation curves of […]