Milk yield persistency in Brazilian Gyr cattle based on a random regression model


Autoria(s): Pereira, R. J.; Verneque, R. S.; Lopes, P. S.; Santana, M. L.; Lagrotta, M. R.; Torres, R. A.; Vercesi Filho, A. E.; Machado, M. A.
Contribuinte(s)

Universidade Estadual Paulista (UNESP)

Data(s)

20/05/2014

20/05/2014

01/01/2012

Resumo

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

With 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.

Formato

1599-1609

Identificador

http://dx.doi.org/10.4238/2012.June.15.9

Genetics and Molecular Research. Ribeirao Preto: Funpec-editora, v. 11, n. 2, p. 1599-1609, 2012.

1676-5680

http://hdl.handle.net/11449/4969

10.4238/2012.June.15.9

WOS:000305519600087

WOS000305519600087.pdf

Idioma(s)

eng

Publicador

Funpec-editora

Relação

Genetics and Molecular Research

Direitos

openAccess

Palavras-Chave #Dairy cattle #covariance function #Genetic parameter #Milk yield persistency
Tipo

info:eu-repo/semantics/article