Estimates of (co)variance components and genetic parameters for growth traits in Suffolk lambs

Tamioso, Priscilla Regina; Filho, Jaime Luiz Alberti; Dias, Laila Talarico; Teixeira, Rodrigo de Almeida

doi:10.1590/s0103-84782013001200016

Cited by 13 publications

(9 citation statements)

References 22 publications

(20 reference statements)

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“…Based on the most appropriate models, direct heritability increased whereas maternal heritability decreased with increasing lamb age. Similar estimates of direct and maternal heritability were reported in Polypay (Hanford et al, 2006) and NSIP Suffolk lambs (Notter, 1998), but lower estimates were reported for Suffolk (Tamioso et al, 2013), NSIP Targhee (Notter and Hough, 1997), and NSIP Polypay lambs (Notter, 1998). Ratios of maternal heritability to direct heritability decreased with age, from 94% for BWT to 30% for PWWT, and were consistent with results summarized by Safari et al (2005).…”

Section: Discussionsupporting

confidence: 82%

“…Proper interpretation of parameter estimates derived from animal models for traits influenced by maternal effects depends on both the structure of the data and the model used for the analysis (Safari et al, 2005). Studies on various sheep breeds have shown important maternal effect on lamb BW (Lewis and Beatson, 1999;Bromley et al, 2000;Wilson et al, 2005;Koyuncu and Duru, 2009;Tamioso et al, 2013;Everett-Hincks et al, 2014). The significant (P < 0.05) maternal effects on BW in these Katahdin lambs show that failure to properly account for maternal effects leads to overestimation of heritability and may result in unrealistic expectations for improvement of additive breeding values.…”

Section: Discussionmentioning

confidence: 99%

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Variance components for direct and maternal effects on body weights of Katahdin lambs

Ngere¹,

Burke²,

Notter³

et al. 2017

Journal of Animal Science

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The aim of this study was to estimate genetic parameters for BW in Katahdin lambs. Six animal models were used to study direct and maternal effects on birth weight (BWT), weaning weight (WWT), and postweaning weight (PWWT) using 41,066 BWT, 33,980 WWT, and 22,793 PWWT records collected over 17 yr in 100 flocks. Models included fixed effects of management group, dam age, type of birth (for BWT) or birth and rearing (for WWT and PWWT), and lamb age at weighing (fitted as a covariate for WWT and PWWT; all < 0.05). Variance components for random effects were estimated in sequentially more complex models and tested for significance with likelihood-ratio tests. A model that fitted only an additive animal effect overestimated additive variance for all BW, resulting in larger estimates of direct heritability than models that included maternal effects. Maternal effects explained variation ( < 0.05) in all BW. Heritability estimates for optimal models were 0.15 ± 0.01 for BWT, 0.18 ± 0.02 for WWT, and 0.20 ± 0.02 for PWWT. Estimates of maternal heritabilities were 0.14 for BWT, 0.10 for WWT, and 0.06 for PWWT, with SE = 0.01. Permanent environmental maternal effects explained 4 to 6% (±1%) of total phenotypic variances for these BW. Litter effects included temporary environmental effects common to littermates and a proportion of the dominance genetic variance and accounted for 16 to 19% (±1%) of phenotypic variance. Correlations between additive direct and maternal genetic effects were -0.14 for BWT, -0.23 for WWT, and -0.04 for PWWT but differed from 0 ( < 0.05) only for WWT. The total heritability predicted the total response in direct and maternal genetic effects from mass selection and was 0.23 for BWT, 0.20 for WWT, and 0.23 for PWWT. Direct and maternal additive, maternal permanent environmental, residual, and phenotypic correlations between BWT and WWT were 0.53 ± 0.05, 0.58 ± 0.06, 0.51 ± 0.06, 0.39 ± 0.01, and 0.44 ± 0.01, respectively; those between BWT and PWWT were 0.45 ± 0.06, 0.58 ± 0.08, 0.36 ± 0.08, 0.33 ± 0.01, and 0.37 ± 0.01 respectively; and those between WWT and PWWT were 0.85, 0.99, 0.92, 0.77, and 0.81, respectively, with SE ≤ 0.02. Therefore, both direct and maternal effects had an important impact on BW in Katahdin lambs. Models that included both additive and permanent environmental maternal effects as well as a temporary environmental litter effect should result in more accurate estimates of breeding values and better selection decisions.

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Section: Discussionsupporting

confidence: 82%

Section: Discussionmentioning

confidence: 99%

Variance components for direct and maternal effects on body weights of Katahdin lambs

Ngere¹,

Burke²,

Notter³

et al. 2017

Journal of Animal Science

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“…Santana et al (2013) obtained similar results in an evaluation of various models in the same population of sheep, but using fewer data. In addition, Mohammadi et al (2015) reported similar results in Lori sheep and Tamioso et al (2013) in Suffolk sheep (BW, 0.17), as did Hanford et al (2003) and Gowane et al (2015) for WW (0.11 and 0.15, respectively), and Eler et al (1995) for BW (0.12) and WW (0.13) in Nelore cattle.…”

Section: (Co)variance Components and Genetic Parameterssupporting

confidence: 51%

“…However, these data are not in agreement with those of Mohammadi et al (2015), who reported low values in Lori sheep this discrepancy could be due to environmental effects. Other studies have also reported low to moderate values for weight gain at weaning and post-weaning of 0.07 and 0.22, respectively (Magalhães et al, 2013;Tamioso et al, 2013;Oliveira et al, 2014;Shiotsuki et al, 2014;Valerio et al, 2015). Therefore, the phenotype of these traits in this sheep population exhibited additive genetic variance, and are good indicators for selection.…”

Section: (Co)variance Components and Genetic Parametersmentioning

confidence: 52%

“…Therefore, improving the genetic quality of the flock through selection is necessary, as is estimating genetic parameters as precisely as possible, and taking into account direct genetic, maternal, and permanent environmental effects with respect to body weight traits. Pre-weaning body weight traits are particularly important (Tamioso et al, 2013;Carvalho et al, 2014;Gholizadeh and Ghafouri-Kesbi, 2015;Jannoune et al, 2015), as the maternal effect decreases with increasing age (Mohammadi et al, 2015). Taking these factors into account prevents selection bias, which may decrease efficiency.…”

Section: Introductionmentioning

confidence: 99%

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Estimation of genetic parameters and genetic changes for growth characteristics of Santa Ines sheep

et al. 2016

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ABSTRACT. Studying genetic parameters and genetic changes in SantaInes sheep is important, because it is the commonest breed in Brazil. This study obtained genetic data from 37,735 pedigree records of lambs over 12 years (2003)(2004)(2005)(2006)(2007)(2008)(2009)(2010)(2011)(2012)(2013)(2014) from 33 flocks in 10 Brazilian States; 11,851 records of performance were available. (Co)variance components, genetic parameters and breeding values estimates were obtained by derivative-free restricted maximum likelihood in a univariate analysis that included maternal additive genetic and maternal permanent environmental effects. Birth weight, weaning weight, weight at 180 days of age, weight at 270 days of age, average daily weight gain in the following states: from birth to weaning, from weaning to 6 months, from 6 months to 9 months, and from weaning to 9 months; presence of 2 E.L. Aguirre et al. Genetics and Molecular Research 15 (3): gmr.15038910 hair in fur and leg muscularity were assessed. (Co)variance component values increased in the weight traits with age. A significant maternal effect was found in the pre-weaned stage that decreased in the postweaned stage. High values were estimated for the maternal permanent environmental effect, possibly because of the extensive grassland that was available. High total heritability values were estimated for all of the traits evaluated. Significant, positive correlations were found between direct and maternal additive genetic traits with a gradual decrease as the lambs gained independence from their mothers. The genetic trends observed were irregular and incremental. Significant genetic variance suggests that direct selection for pre-weaning traits results in indirect selection of maternal abilities, and individual selection of any postweaning trait results in rapid genetic improvement.

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Estimation of (Co)Variance components and genetic parameters of fibre traits in Rambouillet sheep using multi-trait analysis

Ahmad

Khan

Chakraborty

et al. 2021

Trop Anim Health Prod

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Estimates of (co)variance components and genetic parameters for growth traits in Suffolk lambs

Cited by 13 publications

References 22 publications

Variance components for direct and maternal effects on body weights of Katahdin lambs

Variance components for direct and maternal effects on body weights of Katahdin lambs

Estimation of genetic parameters and genetic changes for growth characteristics of Santa Ines sheep

Estimation of (Co)Variance components and genetic parameters of fibre traits in Rambouillet sheep using multi-trait analysis

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