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Genotype by environment interaction and model comparison for growth traits of Santa Ines sheep
Author(s) -
Santana M.L.,
Bignardi A.B.,
Eler J.P.,
Cardoso F.F.,
Ferraz J.B.S.
Publication year - 2013
Publication title -
journal of animal breeding and genetics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.689
H-Index - 51
eISSN - 1439-0388
pISSN - 0931-2668
DOI - 10.1111/jbg.12029
Subject(s) - variance components , variance (accounting) , residual , statistics , biology , estimation , gene–environment interaction , genetic correlation , homogeneous , animal model , herd , genetic variation , genotype , restricted maximum likelihood , zoology , mathematics , genetics , estimation theory , accounting , management , algorithm , combinatorics , endocrinology , economics , business , gene
Summary The objectives of the present study were to compare alternative models for the genetic evaluation and assess the importance of genotype by environment interaction (G×E) in the estimation of genetic parameters and genetic evaluation of birth weight ( BW ), weight at 60 days of age (W60) and weight at 180 days of age (W180) of Santa Ines sheep. Data comprise 7622 BW , 4673 W60 and 2830 W180 records from animals born in 44 Brazilian herds. Four models were used for the analyses: animal model ( AM ) with homogeneous residual variance (1), or heterogeneous residual variance (2), hierarchical reaction norms model ( HRNM ) with homogeneous (1) or heterogeneous residual variance (2). The models that best fit the BW , W60 and W180 data were AM 2, HRNM 1 and HRNM 2 respectively. Thus, models for genetic evaluation that consider heterogeneity of variances are recommended to evaluate growth traits of sheep. The correlation between intercept and slope of the HRNM was higher than 0.70 for all traits studied, indicating that animals with higher average breeding values responded better to improvement in environmental conditions, a fact characterizing the scale effect of G×E. Therefore, G×E is an important factor to be considered in the estimation of genetic parameters and genetic evaluation of growth traits of sheep.