Random regression models for the evaluation of the growth of goats of the Anglonubian breed

G.C Castro,J.E.G Campelo,D.H Cavalcante,M.D.F Carvalho,J.L.R Sarmento,L.A.S Fiqueiredo Filho

doi:10.1590/1678-4162-11501

Abstract

ABSTRACT A total of 6593 weight records collected from 796 male and female Anglo-Nubian goats aged up to 130 days, offspring from 29 sires and 225 dams, were used to compare models and estimate genetic parameters throughout the growth curve by applying random regression models. Direct and maternal additive genetic effects and direct and maternal permanent environmental effects were included as random in the models. The contemporary groups were included as fixed effects and goat age at kidding was included as a covariable (linear and quadratic). The choice of the best model was based on the AIC, BIC and AICc criteria. Variance estimates of the four random effects increased as the animals aged. Direct heritability (h2) rose from 0.13 to 0.40 with age, whereas maternal heritability showed a low value. Genetic correlations of weight between closer ages were high. The most suitable random regression model to compare the fitting of random effects was that which employed the Legendre polynomials of quadratic order with homogeneous variance (3333-1).

Highlights

INTRODUCTIONGoats have a high ability to adapt to adverse environmental conditions, which allows their exploitation across the different regions of Brazil
Goats have a high ability to adapt to adverse environmental conditions, which allows their exploitation across the different regions of Brazil.In the northeastern region of the country, this activity plays an important socioeconomic role, extensive systems are used with smallsized animals, a growth pattern acquired due to genetic and environmental factors to whichBoth together and separately, these factors tend to interfere with the productive efficiency of goats and with the identification of genetically superior animals
The most suitable random regression model to compare the fitting of random effects was that which employed the Legendre polynomials of quadratic order with homogeneous variance (3333-1)

Summary

INTRODUCTION

Goats have a high ability to adapt to adverse environmental conditions, which allows their exploitation across the different regions of Brazil. In the northeastern region of the country, this activity plays an important socioeconomic role, extensive systems are used with smallsized animals, a growth pattern acquired due to genetic and environmental factors to which Both together and separately, these factors tend to interfere with the productive efficiency of goats and with the identification of genetically superior animals. The adoption of breeding programs and the use of methods to more accurately estimate genetic parameters of local herds can help to increase genetic gains obtained with selection In this scenario, understanding the animal growth curve pattern, which is frequently evaluated through sequential weight measurements over time, has become the focus of breeding studies so that they can be included in production systems more efficient for the local reality. The present study proposes to compare random regression models to determine the best suited to describe changes in genetic parameters throughout the growth curve of Anglo-Nubian goats

MATERIAL AND METHODS

RESULTS AND DISCUSSION

CONCLUSIONS