Genetic parameters for production traits of dairy Gyr (Bos indicus)×Holstein cattle estimated with a random regression model

Pereira, Rodrigo Junqueira; Ayres, Denise Rocha; Faro, Lenira El; Filho, Aníbal Eugênio Vercesi; Verneque, Rui da Silva; Albuquerque, Lúcia Galvão de

doi:10.1016/j.livsci.2013.10.003

Cited by 18 publications

(23 citation statements)

References 27 publications

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“…bras., Brasília, v.49, n.5, p.373-383, maio 2014 DOI: 10.1590/S0100-204X2014000500007 with the progress of lactation, but the RRMs showed a slight increase in the last month (Figure 1). This typical U-shape was reported in studies by Bignardi et al (2009) and Miglior et al (2009) with Holstein breed, and by Pereira et al (2013a) with Gyr breed. Possibly, the high estimate for the phenotypic variance, in the first and last months, was due to the smaller number of records in these months (in particular, in the last month not all the cows had test-day records because of the high frequency of short lactations in the breed) (Meyer, 1999).…”

Section: Resultssupporting

confidence: 80%

“…Also Pereira et al (2010) observed the similar estimates as the ones of the present study, but in a lager range (0.09 to 0.33). Costa et al (2005), using Legendre polynomials for the Gyr breed, found higher heritability values, which ranged from 0.71, at the start, to 0.21 at the end of lactation, while Pereira et al (2013aPereira et al ( , 2013b found lower estimates, which ranged from 0.12 to 0.24 and from 0.12 to 0.26, respectively. These last authors used Spline function for estimating heritabilities, which ranged from 0.16 to 0.29 .…”

Section: Resultsmentioning

confidence: 90%

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Random regression models to estimate genetic parameters for milk production of Guzerat cows using orthogonal Legendre polynomials

Peixoto

Santos

Aspilcueta-Borquis

et al. 2014

Pesq. agropec. bras.

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-The objective of this work was to compare random regression models for the estimation of genetic parameters for Guzerat milk production, using orthogonal Legendre polynomials. Records (20,524) of test-day milk yield (TDMY) from 2,816 first-lactation Guzerat cows were used. TDMY grouped into 10-monthly classes were analyzed for additive genetic effect and for environmental and residual permanent effects (random effects), whereas the contemporary group, calving age (linear and quadratic effects) and mean lactation curve were analized as fixed effects. Trajectories for the additive genetic and permanent environmental effects were modeled by means of a covariance function employing orthogonal Legendre polynomials ranging from the second to the fifth order. Residual variances were considered in one, four, six, or ten variance classes. The best model had six residual variance classes. The heritability estimates for the TDMY records varied from 0.19 to 0.32. The random regression model that used a second-order Legendre polynomial for the additive genetic effect, and a fifth-order polynomial for the permanent environmental effect is adequate for comparison by the main employed criteria. The model with a second-order Legendre polynomial for the additive genetic effect, and that with a fourth-order for the permanent environmental effect could also be employed in these analyses.Index terms: Bos indicus, covariance functions, lactation curve, test-day model. Modelos de regressão aleatória para estimação de parâmetros genéticos para produção de leite da raça Guzerá com uso de polinômios ortogonais de LegendreResumo -O objetivo deste trabalho foi comparar modelos de regressão aleatória para a estimação de parâmetros genéticos da produção de leite de Guzerá, com uso dos polinômios ortogonais de Legendre. Foram utilizados 20.524 registros da produção de leite no dia do controle (PLDC) de 2.816 vacas da raça Guzerá em primeira lactação. Agrupadas em 10 classes mensais, as PLDC foram analisadas quanto aos efeitos genéticos aditivos, e aos de ambiente permanente e residual (efeitos aleatórios); enquanto efeitos de grupo de contemporâneos, covariável idade da vaca ao parto (efeito linear e quadrático) e a curva média de lactação foram analisados como efeitos fixos. Trajetórias quanto aos efeitos aditivos genéticos e de ambiente permanente foram modeladas por meio de uma função de covariância com uso do polinômio de Legendre de segunda à quinta ordem. As variâncias residuais foram consideradas em 1, 4, 6 ou 10 classes de variância. O melhor modelo teve seis classes de variância residual. As estimativas de herdabilidade para os registros de PLDC variaram de 0.19 a 0.32. O modelo de regressão aleatória que utilizou o polinômio de Legendre de segunda ordem, quanto ao efeito genético aditivo, e o polinômio de quinta ordem, quanto ao efeito de ambiente permanente, é o mais adequado para a comparação dos principais critérios utilizados. O modelo que utilizou o polinômio de Legendre de segunda ordem, quanto ao efeito genético adi...

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Section: Resultssupporting

confidence: 80%

Section: Resultsmentioning

confidence: 90%

Random regression models to estimate genetic parameters for milk production of Guzerat cows using orthogonal Legendre polynomials

Peixoto

Santos

Aspilcueta-Borquis

et al. 2014

Pesq. agropec. bras.

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“…The heritability estimates tended to be lower in the first 60 d of the lactation and were highest in mid lactation (150-210 DIM), mainly because of the lower residual variances (Figure 4). The heritability estimates obtained were higher than those reported in crossbred B. taurus × B. indicus cattle in Brazil (Bignardi et al, 2009;Pereira et al, 2013), for B. indicus cattle in Kenya (Ilatsia et al, 2007), and from other studies for B. taurus animals raised under tropical environments (Rekaya et al, 1999;Druet et al, 2003;Muasya et al, 2014). The magnitude of the heritability estimate implies an opportunity for a reasonable response to selection for milk production within the dairy cattle population currently on smallholder farms.…”

Section: Parameter Estimates From Rrmcontrasting

confidence: 52%

Genetic evaluation of test-day milk yields from smallholder dairy production systems in Kenya using genomic relationships

Ojango

Mrode

Rege³

et al. 2019

Journal of Dairy Science

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Efforts to improve dairy production in smallholder farming systems of East Africa over the past decade have had limited impact because of the lack of records on performance to guide targeted breeding programs. Estimates of genetic parameters in these systems are lacking. Using data generated through a project ("Germplasm for Dairy Development in East Africa") in Kenya and a genomic relationship matrix from genotypic records, we examined the potential impact of different models handling contemporary groups or herd effects on estimates of genetic parameters using a fixed regression model (FRM) for test-day (TD) milk yields, and the covariance structure for TD milk yield at various stages of lactation for animals using a random regression model (RRM). Models in which herd groups were defined using production levels derived from the data fitted the data better than those in which herds were grouped depending on management practices or were random. Lactation curves obtained for animals under different production categories did not display the typical peak yield characteristic of improved dairy systems in developed countries. Heritability estimates for TD milk yields using the FRM varied greatly with the definition of contemporary herd groups, ranging from 0.05 ± 0.03 to 0.27 ± 0.05 (mean ± standard error). The analysis using the RRM fitted the data better than the FRM. The heritability estimates for specific TD yields obtained by the RRM were higher than those obtained by the FRM. Genetic correlations between TD yields were high and positive for measures within short consecutive intervals but decreased as the intervals between TD increased beyond 60 d and be-came negative with intervals of more than 5 mo. The magnitude of the genetic correlation estimates among TD records indicates that using TD milk records beyond a 60-d interval as repeated measures of the same trait for genetic evaluation of animals on smallholder farms would not be optimal. Although each individual smallholder farmer retains only a few animals, using the genomic relationship between animals to link the large number of farmers operating under specified environments provides a sufficiently large herd-group for which a breeding program could be developed.

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“…O pico de produção ocorreu, em média, entre os dias 35 e 79 da lactação, mais tarde do que o relatado por Pereira et al (2013aPereira et al ( , 2013b e a fase da lactação. Nas DIF analisadas dentro de cada fase da lactação (Tabela 2), observaram-se diferenças entre as classes de ∆F i .…”

Section: Resultsunclassified

“…Ferreira et al (1999) comparam modelos com ou sem o efeito fixo de F i , sobre características de crescimento de bovinos da raça Hereford, e concluíram que não houve diferenças entre as estimativas de herdabilidade ao compararem os modelos. As estimativas de herdabilidade variaram entre 0,17 e 0,22 e foram semelhantes às reportadas por Pereira et al (2013aPereira et al ( , 2013b, que trabalharam com parte do conjunto de dados utilizados no presente estudo.…”

Section: Fase De Lactaçãounclassified

Depressão endogâmica na produção de leite no dia do controle de bovinos Gir leiteiro

Pereira

Júnior

Ayres

et al. 2016

Pesq. agropec. bras.

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Resumo -O objetivo deste trabalho foi estimar o efeito da endogamia sobre a produção de leite e sua persistência durante a lactação, em bovinos Gir leiteiro, bem como determinar o impacto de se considerar ou não o efeito da endogamia na avaliação genética dessa característica. Utilizaram-se 89.490 registros de produção no dia do controle, de 11.675 vacas em primeira lactação. O coeficiente e o incremento de endogamia individuais e o número equivalente de gerações completas de cada indivíduo foram computados. A depressão por endogamia foi estimada pela inclusão do efeito do incremento individual de endogamia, em um modelo de regressão aleatória. As soluções para a depressão por endogamia, de acordo com a classe de incremento individual de endogamia e a quinzena da lactação, variaram entre -1,238 e -0,135 kg, o que indica a redução da produção de leite com o aumento da endogamia. Em níveis mais elevados, a endogamia reduziu a persistência da produção de leite. A inclusão do efeito da endogamia no modelo de avaliação genética não afetou as estimativas de parâmetros genéticos e, praticamente, não alterou a predição dos valores genéticos e a classificação dos animais. Pode-se incluir o efeito da endogamia no modelo estatístico para a avaliação genética da característica produção de leite.Termos para indexação: endogamia, parâmetros genéticos, persistência da produção de leite, regressão aleatória. Inbreeding depression in test-day milk yield of Gyr dairy cattleAbstract -The objective of this work was to estimate the effect of inbreeding on milk yield and its persistency during lactation, in Gyr dairy cattle, as well as to determine the impact of considering or not the effect of inbreeding on the genetic evaluation of this trait. Test-day records (89,490) for milk yield from 11,675 dairy cows at first lactation were used. The individual inbreeding coefficient, the individual increase of inbreeding, and the number of equivalent complete generations of each individual were computed. Inbreeding depression was estimated by including the effect of individual increase of inbreeding in a random regression model. The solutions for inbreeding depression, according to the class of individual increase of inbreeding and stage of lactation, ranged between -1.238 and -0.135 kg, which indicates a reduction of milk yield with the increase of inbreeding. At higher levels of inbreeding, the persistence of milk yield was reduced. The inclusion of the inbreeding effect in the genetic evaluation model did not affect the genetic parameter estimates, with practically no change of the predicted breeding values and rank of animals. The inbreeding effect can be included in the statistical model for the genetic evaluation of milk yield.

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Genetic parameters for production traits of dairy Gyr (Bos indicus)×Holstein cattle estimated with a random regression model

Cited by 18 publications

References 27 publications

Random regression models to estimate genetic parameters for milk production of Guzerat cows using orthogonal Legendre polynomials

Random regression models to estimate genetic parameters for milk production of Guzerat cows using orthogonal Legendre polynomials

Genetic evaluation of test-day milk yields from smallholder dairy production systems in Kenya using genomic relationships

Depressão endogâmica na produção de leite no dia do controle de bovinos Gir leiteiro

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