5 results on '"direct-maternal genetic correlation"'
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2. Estimation of the environmental dam-offspring correlation in beef cattle.
- Author
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Munilla, S. and Cantet, R. J. C.
- Subjects
- *
BEEF cattle reproduction , *ANIMAL breeding , *GENETIC correlations , *CATTLE genetics , *MARKOV chain Monte Carlo , *CATTLE - Abstract
A long standing controversy in animal breeding is related to the strong negative estimates of the direct-maternal genetic correlation obtained when fitting data on maternally influenced traits. In this article, we focused on a model that introduces a new correlation parameter among dam-offspring records. The extant theory allows estimation of the parameter when dams have at most a single offspring. Our goal was to develop an inferential procedure in a more general setting. To do so, we applied a Bayesian approach and we showed that the estimation could be accomplished by introducing a Markov chain Monte Carlo (MCMC) step embedded into a regular Gibbs sampler program. The procedure was implemented by means of an MCMC algorithm known as the Griddy-Gibbs sampler, and a Fortran 90 library was created to accomplish the task. The computer program is available from http://www.agro.uba.ar/ catedras/mg_animal/software/RDBLK. With this tool at hand, we applied the inferential procedure to weaning weight records on beef cattle calves from an Argentinean Hereford herd, and we estimated the marginal distribution of the environmental dam-offspring correlation parameter. The distribution was unimodal and symmetric with a mean value of -0.14 (±0.03) and a 95% high posterior density interval between -0.20 and -0.07, indicating that the model placed a huge mass on negative values of the parameter. Noticeably, the magnitude of the direct-maternal genetic correlation diminished from -0.61 to -0.37 with respect to the standard maternal animal model. This result reinforces the idea that environmental covariances among dam-offspring records may bias the estimate of the direct-maternal genetic correlation. [ABSTRACT FROM AUTHOR]
- Published
- 2015
- Full Text
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3. The impact of direct-maternal genetic correlations on international beef cattle evaluations for Limousin weaning weight
- Author
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Roel F. Veerkamp, Mario P. L. Calus, Renzo Bonifazi, Jan ten Napel, and Jérémie Vandenplas
- Subjects
Population ,Weaning ,Beef cattle ,Animal Breeding and Genomics ,Animal model ,RDM ,beef cattle ,weaning weight ,Linear regression ,Statistics ,Genetics ,Animals ,Fokkerij en Genomica ,Fokkerij & Genomica ,education ,Weaning weight ,Mathematics ,direct-maternal genetic correlation ,education.field_of_study ,Models, Genetic ,Body Weight ,Animal Genetics and Genomics ,Reproducibility of Results ,General Medicine ,interbeef ,Phenotype ,Current practice ,Linear Models ,WIAS ,AcademicSubjects/SCI00960 ,Cattle ,Animal Science and Zoology ,international genetic evaluations ,international estimated breeding values ,Food Science ,Animal Breeding & Genomics - Abstract
In beef cattle maternally influenced traits, estimates of direct-maternal genetic correlations (rdm) are usually reported to be negative. In international evaluations, rdm can differ both within countries (rdm_WC) and between countries (rdm_BC). The rdm_BC are difficult to estimate and are assumed to be zero in the current model for international beef cattle evaluations (Interbeef). Our objective was to investigate re-ranking of international estimated breeding values (IEBVs) in international beef cattle evaluations between models that either used estimated values for rdm or assumed them to be 0. Age-adjusted weaning weights and pedigree data were available for Limousin beef cattle from ten European countries. International EBVs were obtained using a multi-trait animal model with countries modeled as different traits. We compared IEBVs from a model that uses estimated rdm_BC (ranging between −0.14 and +0.14) and rdm_WC (between −0.33 and +0.40) with IEBVs obtained either from the current model that assumes rdm_BC to be 0, or from an alternative model that assumes both rdm_BC and rdm_WC to be 0. Direct and maternal IEBVs were compared across those three scenarios for different groups of animals. The ratio of population accuracies from the linear regression method was used to further investigate the impact of rdm on international evaluations, for both the whole set of animals in the evaluation and the domestic ones. Ignoring rdm_BC, i.e., replacing estimated values with 0, resulted in no (rank correlations > 0.99) or limited (between 0.98 and 0.99) re-ranking for direct and maternal IEBVs, respectively. Both rdm_BC and rdm_WC had less impact on direct IEBVs than on maternal IEBVs. Re-ranking of maternal IEBVs decreased with increasing reliability. Ignoring rdm_BC resulted in no re-ranking for sires with IEBVs that might be exchanged across countries and limited re-ranking for the top 100 sires. Using estimated rdm_BC values instead of considering them to be 0 resulted in null to limited increases in population accuracy. Ignoring both rdm_BC and rdm_WC resulted in considerable re-ranking of animals’ IEBVs in all groups of animals evaluated. This study showed the limited impact of the current practice of ignoring rdm_BC in international evaluations for Limousin weaning weight, most likely because the estimated rdm_BC was close to 0. We expect that these conclusions can be extended to other traits that have reported rdm values in the range of rdm_WC values for weaning weight in Limousin.
- Published
- 2021
4. EFEITOS DA INCLUSÃO OU NÃO DA COVARIÂNCIA GENÉTICA DIRETA-MATERNAL NO MODELO E DOS VALORES REAIS DAS (CO)VARIÂNCIAS SOBRE SUAS ESTIMATIVAS PARA PESO À DESMAMA EM BOVINOS DE CORTE.
- Author
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Ferreira, Jorge Luis, De Los Reyes Borjas, Arcadio, Roberto Carvalheiro, Roberto, and Lôbo, Raysildo Barbosa
- Subjects
BEEF cattle weight ,ANIMAL genetics ,SIMULATION methods & models ,STATISTICAL correlation ,ANALYSIS of variance ,ESTIMATION theory ,MATHEMATICAL models - Abstract
This study aimed to compare estimates of (co)variances considering the effect of direct maternal genetic correlation (-0,50; -0,25; +0,25; +0,50); the ratios between the direct and maternal genetic variances (75:75; 50:100; 100:50) and two models which included (M2) or not (M1) the direct maternal genetic covariance. Stochastic simulation of twenty replicates of a closed and randomly mated herd of cattle was carried out for twenty years of selection. The base population was not related, nonselected and randomly sampled. (Co)variance estimates were obtained under single trait animal model using MTDFREML application. The model was not significant on estimates of maternal permanent environmental variance. The genetic direct-maternal correlation influenced all (co)variance estimates significantly (P<0,05). The ratios of genetic direct and maternal variances significantly affected (P<0,05) only estimates of genetic direct and maternal variances. Regarding negative direct-maternal genetic correlation, M1 underestimated direct and maternal variances while overestimated both when that correlation was positive. Reliable and accurate (co)variance estimates for weaning weight in beef cattle depend on the adequacy of the model as well as their actual values. [ABSTRACT FROM AUTHOR]
- Published
- 2011
- Full Text
- View/download PDF
5. Efeitos da inclusão ou não da covariância genética direta-maternal no modelo e dos valores reais das (CO)variâncias sobre suas estimativas para peso à desmama em bovinos de corte
- Author
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Raysildo Barbosa Lôbo, Arcadio de los Reyes Borjas, Roberto Carvalheiro, and Jorge Luís Ferreira
- Subjects
direct-maternal genetic correlation ,General Veterinary ,simulation ,lcsh:S ,Variance (accounting) ,Beef cattle ,Biology ,Genetic correlation ,Correlation ,lcsh:Agriculture ,Animal model ,cattle ,co-variance estimates ,Statistics ,VARIAÇÃO GENÉTICA (ESTIMATIVA) ,Trait ,Herd ,Animal Science and Zoology ,lcsh:Animal culture ,Selection (genetic algorithm) ,lcsh:SF1-1100 - Abstract
This study aimed to compare estimates of (co)variances considering the effect of direct maternal genetic correlation (-0,50; -0,25; +0,25; +0,50); the ratios between the direct and maternal genetic variances (75:75; 50:100; 100:50) and two models which included (M2) or not (M1) the direct maternal genetic covariance. Stochastic simulation of twenty replicates of a closed and randomly mated herd of cattle was carried out for twenty years of selection. The base population was not related, non-selected and randomly sampled. (Co)variance estimates were obtained under single trait animal model using MTDFREML application. The model was not significant on estimates of maternal permanent environmental variance. The genetic direct-maternal correlation influenced all (co)variance estimates significantly (P
- Published
- 2011
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