Genetic and environmental variance components for milk yield across regions, time periods and herd levels for Holstein cattle in Mexico
Additive genetic, permanent environmental, and temporaryenvironmental variance components were estimated for 86,812milk yield records for different regions, time periods andherd-years according their standard deviation levels forHolstein cattle in Mexico. Variances were estimated usingREML and an an...
| Autores: | , , |
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| Tipo de recurso: | artículo |
| Estado: | Versión publicada |
| Fecha de publicación: | 2004 |
| País: | México |
| Institución: | Universidad de Guanajuato |
| Repositorio: | Redalyc-UG |
| OAI Identifier: | oai:redalyc.org:95914504 |
| Acceso en línea: | https://www.redalyc.org/articulo.oa?id=95914504 |
| Access Level: | acceso abierto |
| Palabra clave: | Veterinaria heritability repeatability genetic variance Heterogeneous variance |
| Sumario: | Additive genetic, permanent environmental, and temporaryenvironmental variance components were estimated for 86,812milk yield records for different regions, time periods andherd-years according their standard deviation levels forHolstein cattle in Mexico. Variances were estimated usingREML and an animal model. Additive genetic and residualvariances were bigger in the Northern region and for the mostrecent period 1991-1997, both being associated with higherproduction levels. Heritability estimates for regions were from0.27 to 0.31 ± 0.02, and for time periods were from 0.20 to0.27 ± 0.03 using all lactations. Heritability values for regionand time periods in first lactation cows were from 0.21 to0.25 ± 0.02 and 0.21 to 0.31 ± 0.02, respectively. Heritabilityaccording to the standard deviation levels were from 0.21 to0.24 ± 0.01. Repeatability values ranged from 0.36 to 0.51.Differences (P<0.05) in the additive and environmentalvariances were found classifying herds-years for milk yieldstandard deviation level, through regions, periods of time andtheir combinations. Different degrees of heterogeneity ofvariances were found according to the classification criterionused. Results obtained in this study suggest the need to letgenetic evaluation procedures account for these differences invariance according to region, in order to reduce bias and toincrease the accuracy of predicted breeding values |
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