Estimação de parâmetros genéticos para produção de leite de vacas da raça Holandesa via regressão aleatória

Dorneles, Cristian Kelen Pinto; Cobuci, Jaime Araújo; Rorato, Paulo Roberto Nogara; Weber, Tomás; Lopes, Jader Silva; Oliveira, Henrique Nunes de

doi:10.1590/s0102-09352009000200018

Cited by 6 publications

(3 citation statements)

References 11 publications

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“…B-spline and Wilmink showed similar estimates. Several studies in Holstein cattle using RRM reported similar trend for TD heritability estimates as obtained in this study, Olori et al (1999) and Kettunen et al (2000), and in Brazil by Cobuci et al (2005), Araújo et al (2006), Melo et al (2007) and Dorneles et al (2009).…”

Section: Resultssupporting

confidence: 88%

Random regression models using different functions to model test-day milk yield of Brazilian Holstein cows

Bignardi

Faro²,

Torres³

et al. 2011

Genet. Mol. Res.

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ABSTRACT. We analyzed 152,145 test-day records from 7317 first lactations of Holstein cows recorded from 1995 to 2003. Our objective was to model variations in test-day milk yield during the first lactation of Holstein cows by random regression model (RRM), using various functions in order to obtain adequate and parsimonious models for the estimation of genetic parameters. Test-day milk yields were grouped into weekly classes of days in milk, ranging from 1 to 44 weeks. The contemporary groups were defined as herd-test-day. The analyses were performed using a single-trait RRM, including the direct additive, permanent environmental and residual random effects. In addition, contemporary group and linear and quadratic effects of the age of cow at calving were included as fixed effects. The mean trend of milk yield was modeled with a fourth-order orthogonal Legendre polynomial. The additive genetic and permanent environmental covariance functions were estimated by random regression on two parametric functions, Ali and Schaeffer and Wilmink, and on B-spline functions of days in milk. The covariance components and the genetic parameters were estimated by the restricted maximum likelihood method. Results from RRM parametric and B-spline functions were compared to RRM on Legendre polynomials and with a multi-trait analysis, using the same data set. Heritability estimates presented similar trends during mid-lactation (13 to 31 weeks) and between week 37 and the end of lactation, for all RRM. Heritabilities obtained by multi-trait analysis were of a lower magnitude than those estimated by RRM. The RRMs with a higher number of parameters were more useful to describe the genetic variation of test-day milk yield throughout the lactation. RRM using B-spline and Legendre polynomials as base functions appears to be the most adequate to describe the covariance structure of the data.

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Section: Resultssupporting

confidence: 88%

Random regression models using different functions to model test-day milk yield of Brazilian Holstein cows

Bignardi

Faro²,

Torres³

et al. 2011

Genet. Mol. Res.

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show abstract

“…Estes valores diferiram dos relatados por Dionello et al (2006), os quais utilizaram modelos de repetibilidade e de regressão aleatória na estimativa de parâmetros genéticos para produção de leite, obtendo 7,08 kg 2 para VG, 7,79 kg 2 para VR e 16,76 kg 2 para VF. Entretanto, a VG relatada por Dorneles at al. (2009) foi semelhante a do presente trabalho (2,38 a 3,14 kg 2 ), sendo a variância residual bem inferior (3,88 vs 25,03 kg 2 ).…”

Section: Produção De Leiteunclassified

“…Em Dorneles et al (2009), o coeficiente de herdabilidade para a produção no dia do controle variou de 0,14 a 0,20 com gradual aumento no decorrer do período de lactação. Por outro lado, herdabilidades maiores foram observadas por Jamrozik e Schaeffer (1997), com valores variando de 0,40 a 0,48, com maior estimativa encontrada no início da lactação.…”

Section: Produção De Leiteunclassified

Parâmetros genéticos e fenotípicos do perfil de ácidos graxos do leite de vacas da raça holandesa

Rodriguez¹

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Graduação em "Ciência Animal e Pastagens" pela oportunidade de realização do doutorado. Ao orientador Prof. Dr. Gerson Barreto Mourão, pela orientação, ensinamentos e confiança depositada para o desenvolvimento deste trabalho. Ao amigo Fábio Pértile, pela imensa ajuda, dedicação, companheirismo e experiência transmitida nas análises de laboratório. Ao amigo Gregori Rovadoscki, pelo incentivo, carinho e apoio nas análises computacionais realizadas. Às queridas amigas Juliana Petrini, Johanna Ramírez Diaz e Laiza Helena de Souza Iung, pela dedicação exclusiva na condução deste trabalho, pelo apoio profissional e pessoal, e por torcerem muito para que esta etapa fosse concluída.

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Genetic parameters for production traits in primiparous Holstein cows estimated by random regression models

et al. 2011

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-The objective of this study was to estimate genetic parameters for milk, fat and protein yields of Holstein cows using 56,508; 35,091 and 8,326 test-day milk records from 7,015, 4,476 and 1,114 cows, calves of 359, 246 and 90 bulls, respectively. The additive genetic and permanent environmental effects were estimated using REML. Random regression models with Legendre polynomials from order 3 to 6 were used. Residual variances were considered homogeneous over the lactation period. The estimates of variance components showed similar trends, with an increase of the polynomial order for each trait. The heritability estimates ranged from 0.14 to 0.31; 0.03 to 0.21 and 0.09 to 0.33 for milk, fat and protein yield, respectively. Genetic correlations among milk, fat and protein yields ranged from 0.02 to 1.00; 0.34 to 1.00 and 0.42 to 1.00, respectively. Models with higher order Legendre polynomials are the best suited to adjust test-day data for the three production traits studied. herdabilidade variaram, respectivamente, de 0,14 a 0,31; 0,03 a 0,21; e 0,09 a 0,33 para as produções de leite, de gordura e de proteína. As correlações genéticas entre produções de leite, gordura e proteína do leite variaram de 0,02 a 1,00; 0,34 a 1,00 e 0,42 a 1,00, respectivamente. Os modelos com polinômio de Legendre de maior ordem são os mais adequados para ajuste da produção no dia do controle das três características produtivas.Palavras-chave: dia do controle, herdabilidade, produção de gordura, produção de leite, produção de proteína Revista Brasileira de Zootecnia

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Estimação de parâmetros genéticos para produção de leite de vacas da raça Holandesa via regressão aleatória

Cited by 6 publications

References 11 publications

Random regression models using different functions to model test-day milk yield of Brazilian Holstein cows

Random regression models using different functions to model test-day milk yield of Brazilian Holstein cows

Parâmetros genéticos e fenotípicos do perfil de ácidos graxos do leite de vacas da raça holandesa

Genetic parameters for production traits in primiparous Holstein cows estimated by random regression models

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