Milk yield persistency in brazilian gyr cattle based on a random regression model.

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dc.contributorR. J. PEREIRA, UNESP; RUI DA SILVA VERNEQUE, CNPGL; P. S. LOPES, UFV; M. L. SANTANA JUNIOR, UFMT; M. R. LAGROTTA, UFV; R. A. TORRES, UFV; A. E. VERCESI FILHO, APTA; MARCO ANTONIO MACHADO, CNPGL.
dc.creatorPEREIRA, R. J.
dc.creatorVERNEQUE, R. da S.
dc.creatorLOPES, P. S.
dc.creatorSANTANA JUNIOR, M. L.
dc.creatorLAGROTTA, M. R.
dc.creatorTORRES, R. A.
dc.creatorVERCESI FILHO, A. E.
dc.creatorMACHADO, M. A.
dc.date2024-02-09T18:32:37Z
dc.date2024-02-09T18:32:37Z
dc.date2012-12-12
dc.date2012
dc.date.accessioned2026-07-07T03:51:18Z
dc.descriptionWith the objective of evaluating measures of milk yield persistency, 27,000 test-day milk yield records from 3362 first lactations of Brazilian Gyr cows that calved between 1990 and 2007 were analyzed with a random regression model. Random, additive genetic and permanent environmental effects were modeled using Legendre polynomials of order 4 and 5, respectively. Residual variance was modeled using five classes. The average lactation curve was modeled using a fourth-order Legendre polynomial. Heritability estimates for measures of persistency ranged from 0.10 to 0.25. Genetic correlations between measures of persistency and 305-day milk yield (Y305) ranged from -0.52 to 0.03. At high selection intensities for persistency measures and Y305, few animals were selected in common. As the selection intensity for the two traits decreased, a higher percentage of animals were selected in common. The average predicted breeding values for Y305 according to year of birth of the cows had a substantial annual genetic gain. In contrast, no improvement in the average persistency breeding value was observed. We conclude that selection for total milk yield during lactation does not identify bulls or cows that are genetically superior in terms of milk yield persistency. A measure of persistency represented by the sum of deviations of estimated breeding value for days 31 to 280 in relation to estimated breeding value for day 30 should be preferred in genetic evaluations of this trait in the Gyr breed, since this measure showed a medium heritability and a genetic correlation with 305-day milk yield close to zero. In addition, this measure is more adequate at the time of peak lactation, which occurs between days 25 and 30 after calving in this breed.
dc.identifierGenetics and Molecular Research, v. 11, n. 2., p. 1599-1609, 2012.
dc.identifierhttp://www.alice.cnptia.embrapa.br/alice/handle/doc/942286
dc.identifierhttps://doi.org/10.4238/2012.june.15.9
dc.identifier.urihttp://hdl.handle.net/123456789/444945
dc.languageeng
dc.rightsopenAccess
dc.subjectParametros genéticos
dc.subjectFunção de covariância
dc.subjectProdução de leite
dc.subjectGado Leiteiro
dc.titleMilk yield persistency in brazilian gyr cattle based on a random regression model.
dc.typeArtigo de periódico

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