Document Detail

Genetic effects on preweaning weight gain of Nelore-Hereford calves according to different models and estimation methods.
MedLine Citation:
PMID:  17032785     Owner:  NLM     Status:  MEDLINE    
Additive and nonadditive genetic effects on preweaning weight gain (PWG) of a commercial crossbred population were estimated using different genetic models and estimation methods. The data set consisted of 103,445 records on purebred and crossbred Nelore-Hereford calves raised under pasture conditions on farms located in south, southeast, and middle west Brazilian regions. In addition to breed additive and dominance effects, the models including different epistasis covariables were tested. Models considering joint additive and environment (latitude) by genetic effects interactions were also applied. In a first step, analyses were carried out under animal models. In a second step, preadjusted records were analyzed using ordinary least squares (OLS) and ridge regression (RR). The results reinforced evidence that breed additive and dominance effects are not sufficient to explain the observed variability in preweaning traits of Bos taurus x Bos indicus calves, and that genotype x environment interaction plays an important role in the evaluation of crossbred calves. Data were ill-conditioned to estimate the effects of genotype x environment interactions. Models including these effects presented multicolinearity problems. In this case, RR seemed to be a powerful tool for obtaining more plausible and stable estimates. Estimated prediction error variances and variance inflation factors were drastically reduced, and many effects that were not significant under ordinary least squares became significant under RR. Predictions of PWG based on RR estimates were more acceptable from a biological perspective. In temperate and subtropical regions, calves with intermediate genetic compositions (close to 1/2 Nelore) exhibited greater predicted PWG. In the tropics, predicted PWG increased linearly as genotype got closer to Nelore.
R Carvalheiro; E C G Pimentel; V Cardoso; S A Queiroz; L A Fries
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Journal of animal science     Volume:  84     ISSN:  1525-3163     ISO Abbreviation:  J. Anim. Sci.     Publication Date:  2006 Nov 
Date Detail:
Created Date:  2006-10-11     Completed Date:  2006-12-18     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  8003002     Medline TA:  J Anim Sci     Country:  United States    
Other Details:
Languages:  eng     Pagination:  2925-33     Citation Subset:  IM    
Departamento de Zootecnia, Universidade Estadual Paulista, Campus Jaboticabal, Sao Paulo, Brazil.
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MeSH Terms
Cattle / genetics*,  growth & development*
Crosses, Genetic
Models, Biological
Weight Gain / genetics*

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