Heteroskedasticity for weaning weight of Charolais-Zebu crossbred calves

Toral, Fábio Luiz Buranelo; Júnior, Roberto Augusto de Almeida Torres; Lopes, Paulo Sávio; Cardoso, F. F.; Silva, Luiz Otávio Campos da

doi:10.1590/s1516-35982012000500013

Cited by 4 publications

(6 citation statements)

References 17 publications

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“…This result shows the superiority of the Angus breed, which stands out for having a greater precocity of growth and termination than Zebu. This may be related to the history of selection of the Angus breed, which is known and selected for precocity of growth, whereas the Nelore breed has only been recently selected for growth (Toral et al, 2012), not having been subjected to systematic selection processes in its location of origin.…”

Section: Resultsmentioning

confidence: 99%

Genetic evaluation models for post-weaning weight gain in a multibreed Angus-Nelore population

Prestes

Oliveira

Mello

et al. 2019

Pesq. agropec. bras.

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The objective of this work was to identify the most suitable model for the genetic evaluation of post-weaning weight gain in a multibreed Angus-Nelore population. Three models were tested using the Bayesian inference method: traditional animal model (M1), multibreed animal model without (M2) and with segregation (M3). The choice of the best model followed the criteria: number of parameters (Np), deviance information criterion (DIC), conditional predictive ordinate (CPO), and deviance based on Bayes factors. Spearman’s rank correlations were estimated for the top 10, 20, and 30% sires. M1 presented the highest values for all criteria, except for Np, and the lowest direct heritability estimate of 0.15±0.01. The heritability estimates for M2 and M3 were higher and similar, being 0.29±0.02 and 0.27±0.02, respectively. M3 showed the lowest values for mean deviance, DIC, and CPO, being the best-fitting model among the three tested. Spearman’s correlation between the predicted genetic values for the models ranged from 0.69 to 0.99. The multibreed models are the most suitable for the genetic evaluation of multibreed populations, and M3 shows the best fit for the studied population.

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Section: Resultsmentioning

confidence: 99%

Genetic evaluation models for post-weaning weight gain in a multibreed Angus-Nelore population

Prestes

Oliveira

Mello

et al. 2019

Pesq. agropec. bras.

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“…Other works on multiple trait evaluations, carried out with data on beef (Cardoso & Tempelman, 2004;Toral et al, 2012;Lukaszewicz et al, 2015) and dairy (Heins et al, 2011;VanRaden et al, 2011) cattle, showed that variances and heritabilities are specific to each genetic group. Similar results were obtained in the present study, since the additive genetic variances and heritabilities of AFC and 305MY were higher in the 1/2HG groups than in the 5/8HG and 3/4HG groups (Table 3).…”

Section: Resultsmentioning

confidence: 99%

“…The lowest averages a posteriori were observed in groups 5/8HG and 3/4HG. These differences may be a consequence of the different processes and intensities of selection to which the different genetic groups were subjected to (Toral et al, 2012).…”

Section: Resultsmentioning

confidence: 99%

Genetic analysis of productive and reproductive traits in multiple-breed dairy cattle populations

Ribeiro

Merlo²,

Gouveia

et al. 2017

Pesq. agropec. bras.

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-The objective of this work was to determine whether the random regression model using linear splines (RRMLS) is suitable to estimate the genetic parameters for productive and reproductive traits of a multiple-breed dairy cattle population, as well as to investigate the effect of the genetic group of the progeny on the genetic merit of the sire. The multiple-trait model (MTM) and the RRMLS with one knot fitted for every genetic group were used to obtain the genetic parameters. Records of 1/2 Holstein + 1/2 Gyr (1/2HG), 5/8 Holstein + 3/8 Gyr (5/8HG), and 3/4 Holstein + 1/4 Gyr (3/4HG) crossbreed dams were considered. The RRMLS showed better fitting. The additive and residual variances estimated by the MTM and the RRMLS were similar. Heritability varied from 0.20 to 0.33 for age at first calving, from 0.09 to 0.22 for first lactation length, and from 0.15 to 0.35 for first lactation 305-day milk yield, according to the genetic composition of the dams. The RRMLS is suitable to estimate the genetic parameters for productive and reproductive traits of multiple-breed dairy cattle populations. The genetic merit of the sires is affected by the genetic group of the progeny by which they are evaluated.Index terms: Gyr, heritability, heterosis, Holstein, selection. Análise genética de características produtivas e reprodutivas em populações multirraciais de bovinos leiteirosResumo -O objetivo deste trabalho foi verificar se o modelo de regressão aleatória com polinômios lineares do tipo spline (MRAPLS) é adequado para estimar os parâmetros genéticos de características produtivas e reprodutivas em uma população multirracial de bovinos leiteiros, bem como investigar o efeito do grupo genético da progênie sobre o mérito genético do touro. Foram utilizados o modelo multicaracterístico (Mult) e o MRAPLS com nós ajustados aos grupos genéticos, para obtenção dos parâmetros genéticos. Foram considerados os registros de vacas 1/2 Holandesa + 1/2 Gir (1/2HG), 5/8 Holandesa + 3/8 Gir (5/8HG) e 3/4 Holandesa + 1/4 Gir (3/4HG). O MRAPLS apresentou os melhores ajustes. As variâncias aditivas e residuais estimadas por Mult e MRAPLS foram semelhantes. As herdabilidades variaram de 0,20 a 0,33 para idade ao primeiro parto, de 0,09 a 0,22 para duração da primeira lactação e de 0,15 a 0,35 para produção de leite em até 305 dias na primeira lactação, de acordo com a composição genética das vacas. O MRAPLS é adequado para estimar parâmetros genéticos de características produtivas e reprodutivas em populações multirraciais de bovinos leiteiros. O mérito genético do touro é influenciado pelo grupo genético da progênie por meio do qual ele é avaliado.Termos para indexação: Gir, herdabilidade, heterose, Holandesa, seleção.

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“…Feeding systems and specific management for each breed group may be used to improve productivity in multiple-breed cattle production. This can result in heterogeneity of residual variance (Toral et al, 2012). In fact, models with heterogeneous residual variances presented a better fit when compared with the ones with homogeneous residual variances for the genetic evaluation of postweaning weight gain of Nellore-Hereford crosses (Cardoso et al, 2005).…”

Section: Field Datamentioning

confidence: 98%

“…The heterogeneity of variances and covariances among purebred and crossbred cows could occur in multiple breed populations (VanRaden et al, 2007) due to the use of different selection intensities and specific selection processes in groups with different genetic composition (Toral et al, 2012). Therefore, the development and implementation of genetic evaluations that account for genotypic means, genetic covariances among relatives (Lo et al, 1993), and the existence of specific genetic variances for each different breed group (Lukaszewicz et al, 2015) can contribute to the genetic improvement of multiple-breed populations.…”

Section: Introductionmentioning

confidence: 99%

Multiple trait and random regression models using linear splines for genetic evaluation of multiple breed populations

Ribeiro

Raidan

Barbosa

et al. 2019

Journal of Dairy Science

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This study aimed to verify if random regression models using linear splines (RRMLS) are suitable for identifying genetic parameters in multiple-breed populations and also to investigate whether an interaction exists between the breeding value (BV) of sires and their progeny breed group. Ten populations were simulated by crossing 2 breeds with distinct genetic variance and nonzero segregation variance. To obtain the genetic parameters, 2 models were used: a multiple-trait model (MULT), in which the trait was considered distinct when evaluated in each group (1/2P 1 + 1/2P 2 , 5/8P 1 + 3/8P 2 , and 3/4P 1 + 1/4P 2 ), and a RRMLS with the spline polynomial knots adjusted to these same groups. The genetic parameters estimated through MULT and RRMLS did not differ from the simulated values. The correlations between BV (simulated and estimated) of animals were high and varied from 0.74 to 0.76, which indicates the efficiency of using MULT and RRMLS for predicting BV. Using field data, the traits age at first calving (AFC), first lactation length (LL), and 305-d milk yield (MY-305) from a multiple-breed population of Holstein-Gyr cattle were analyzed. The BV of animals were modeled through RRMLS with 3, 5, and 7 knots, distributed in accordance with the fraction of Holstein breed in each progeny breed group. It was verified that RRMLS with 7 knots for adjusting mean trajectories and genetic effects, with homogeneous residual variance, best fit AFC and LL. For MY-305, the best fit for mean trajectory and genetic effects was the RRMLS with 5 knots and with homogeneous residual variance. The posterior means of heritability varied from 0.21 to 0.48, 0.21 to 0.38, and 0.10 to 0.33 for AFC, LL, and MY-305, respectively. Estimates from genetic parameters obtained by using RRMLS with field data showed that this model is a useful tool for genetic evaluations of populations formed by a great number of breed groups. An interaction occurred between the BV of sires and their progeny breed group, and the genetic parameters for AFC, LL, and MY-305 traits from a multiple-breed population depend on breed composition of the progeny from which the evaluations are based.

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Heteroskedasticity for weaning weight of Charolais-Zebu crossbred calves

Cited by 4 publications

References 17 publications

Genetic evaluation models for post-weaning weight gain in a multibreed Angus-Nelore population

Genetic evaluation models for post-weaning weight gain in a multibreed Angus-Nelore population

Genetic analysis of productive and reproductive traits in multiple-breed dairy cattle populations

Multiple trait and random regression models using linear splines for genetic evaluation of multiple breed populations

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