Variance components due to direct and maternal effects for growth traits of Australian beef cattle

Genetic and phenotypic parameters of growth traits from birth to 1 year of age were compared in a multibreed Beef Synthetic (SY) and a purebred Hereford (HE) population managed together under the same environmental conditions and selected for growth rate from 1961 to 1979. Growth traits studied were birth weight, preweaning and postweaning gains. Records of 2077 calves of 70 HE and 100 SY paternal half-sib families were used for analysis. Except for birth weight, phenotypic variances of growth traits were similar for the synthetic (SY) and purebred (HE) populations, but genetic variances were larger in SY than in HE for all growth traits except postweaning gain in males. The coefficients of variation were comparable for all the traits studied in the two populations, indicating that phenotypic variations in the multibreed population and the purebred population were similar. Key words: Variance components, heritability, beef cattle

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

Ciência Rural ◽

10.1590/s0103-84782013001200016 ◽

2013 ◽

Vol 43 (12) ◽

pp. 2215-2220 ◽

Cited By ~ 6

Author(s):

Priscilla Regina Tamioso ◽

Jaime Luiz Alberti Filho ◽

Laila Talarico Dias ◽

Rodrigo de Almeida Teixeira

Keyword(s):

Maternal Effects ◽

Variance Components ◽

Genetic Parameters ◽

Growth Traits ◽

Genetic Effect ◽

Additive Genetic Effect ◽

Ratio Test ◽

Effect Model ◽

Estimate Heritability ◽

Heritability Estimates

The study aimed to estimate the components of (co)variance and heritability for weights at birth (BW), weaning (WW) and 180 days of age (W180), as well as the average daily gains from birth to weaning (ADG1), birth to 180 days of age (ADG2) and weaning to 180 days of age (ADG3) in Suffolk sheep. Thus, three different single-trait animal models were fitted, considering the direct additive genetic effect (Model 1), the direct additive genetic and maternal permanent environmental effects (Model 2), and in Model 3, in addition to those in Model 2, the maternal additive genetic effect was included. After comparing models through the likelihood ratio test (LRT), model 3 was chosen as the most appropriate to estimate heritability for BW, WW and ADG1. Model 2 was considered as the best to estimate the coefficient of heritability for W180 and ADG2, and model 1 for ADG3. Direct heritability estimates were inflated when maternal effects were ignored. According to the most suitable models, the heritability estimates for BW, WW, W180, ADG1, ADG2 and ADG3 were 0.06, 0.08, 0.09, 0.07, 0.08 and 0.07, respectively, indicating low possibility of genetic gain through individual selection. The results show the importance of including maternal effects in the models to properly estimate genetic parameters even at post-weaning ages.

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Estimates of direct and maternal genetic parameters for weight traits and backfat thickness in a multibreed population of beef cattle

Canadian Journal of Animal Science ◽

10.4141/a99-014 ◽

1999 ◽

Vol 79 (4) ◽

pp. 433-439 ◽

Cited By ~ 11

Author(s):

J. J. Tosh ◽

R. A. Kemp ◽

D. R. Ward

Keyword(s):

Beef Cattle ◽

Maternal Effects ◽

Variance Components ◽

Genetic Parameters ◽

Genetic Correlations ◽

Backfat Thickness ◽

Residual Effects ◽

Parameter Estimates ◽

Ratio Test ◽

Environmental Correlations

Variance components were estimated for weight at birth, weaning, and 365 d of age, and yearling ultrasonic backfat thickness in a multibreed population of beef cattle. Data (n = 5880) were available on F1 animals and various crosses leading up to, and including, a composite breed (7/16 British, 1/4 Charolais, 1/4 Simmental, and 1/16 Limousin). Single- and two-trait analyses were conducted using an animal model and derivative-free REML procedures. Covariates representing fractional contributions of each of the four purebred groups and average heterotic effects, both direct and maternal, accounted for breed composition. Direct and maternal genetic, maternal permanent environmental, and residual effects were the random variables. Only minor differences existed between parameter estimates obtained from the various analyses. Mean direct heritabilities were 0.51, 0.33, 0.48, and 0.37 for weight at birth, weaning, and 365-d, and backfat, respectively, which, though well within the range of published estimates, seemed higher than average, indicating diversity in the founding purebreds. Mean maternal heritabilites were 0.09, 0.13, and 0.08 for the three consecutive weights. A likelihood ratio test showed maternal heritability and(or) the direct-maternal correlation was important (P < 0.001) for 365-d weight. Averaged across weights, the direct-maternal correlation was 0.07, lacking evidence of genetic antagonism. No age of dam or random maternal effects on backfat were apparent. Phenotypic correlations between weight at birth and weaning and weight at weaning and 365-d were 0.46 and 0.76, respectively. Though moderate between birth and weaning weight, maternal genetic and permanent environmental correlations between weaning and 365-d weight approached unity, demonstrating maternal carryover effects. Phenotypic and genetic correlations of 0.19 and –0.13, respectively, implied a limited association between 365-d weight and backfat, which possibly would have been stronger had fat been measured later in life. Estimates of variance components suitable for general use can be obtained from data from multibreed animals by considering breed and heterotic effects. Key words: Beef cattle, crossbreds, genetic parameters, heritability, maternal effects

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Estimation of (Co)variance Components and Genetic Parameters of Growth Traits in Beef Cattle

Journal of Applied Animal Research ◽

10.1080/09712119.2004.9706512 ◽

2004 ◽

Vol 26 (2) ◽

pp. 77-82

Author(s):

Hailu Dadi ◽

S. J. Schoeman ◽

G. F. Jordaan

Keyword(s):

Beef Cattle ◽

Variance Components ◽

Genetic Parameters ◽

Growth Traits

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Across population genetic parameters for wool, growth, and reproduction traits in Australian Merino sheep. 2. Estimates of heritability and variance components

Australian Journal of Agricultural Research ◽

10.1071/ar06162 ◽

2007 ◽

Vol 58 (2) ◽

pp. 177 ◽

Cited By ~ 36

Author(s):

E. Safari ◽

N. M. Fogarty ◽

A. R. Gilmour ◽

K. D. Atkins ◽

S. I. Mortimer ◽

...

Keyword(s):

Maternal Effects ◽

Variance Components ◽

Genetic Parameters ◽

Growth Traits ◽

Fibre Diameter ◽

Production Traits ◽

Merino Sheep ◽

Reproduction Traits ◽

Fleece Weight ◽

Australian Merino

Precise estimates of genetic parameters are required for genetic evaluation systems. This study combined data from 7 research resource flocks across Australia to estimate variance components and genetic parameters for production traits in the Australian Merino sheep. The flocks were maintained for several generations and represented contemporary Australian Merino fine, medium, and broad wool bloodlines over the past 30 years. Over 110 000 records were available for analysis for each of the major wool traits, and 50 000 records for reproduction and growth traits with over 2700 sires and 25 000 dams. A linear mixed animal model was used to analyse 6 wool traits comprising clean fleece weight (CFW), greasy fleece weight (GFW), fibre diameter (FD), yield (YLD), coefficient of variation of fibre diameter (CVFD), and standard deviation of fibre diameter (SDFD), 4 growth traits comprising birth weight (BWT), weaning weight (WWT), yearling weight (YWT), and hogget weight (HWT), and 4 reproduction traits comprising fertility (FER), litter size (LS), lambs born per ewe joined (LB/EJ), and lambs weaned per ewe joined (LW/EJ). The range of direct heritability estimates for the wool traits was 0.42 ± 0.01 for CFW to 0.68 ± 0.01 for FD. For growth traits the range was 0.18 ± 0.01 for BWT to 0.38 ± 0.01 for HWT, and for reproduction traits 0.045 ± 0.01 for FER to 0.074 ± 0.01 for LS. Significant maternal effects were found for wool and growth, but not reproduction traits. There was significant covariance between direct and maternal genetic effects for all wool and growth traits except for YWT. The correlations between direct and maternal effects ranged from –0.60 ± 0.02 for GFW to –0.21 ± 0.10 for SDFD in the wool traits and from –0.21 ± 0.03 for WWT to 0.25 ± 0.08 for HWT in the growth traits. Litter effects were significant for all wool and growth traits and only for LS in reproduction traits. The mating sire was fitted in the models for reproduction traits and this variance component accounted for 21, 17, and 8% of the total phenotypic variation for FER, LB/EJ, and LW/EJ, respectively. The implications of additional significant variance components for the estimation of heritability are discussed.

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Estimating dominance genetic variances for growth traits in American Angus males using genomic models

Journal of Animal Science ◽

10.1093/jas/skz384 ◽

2019 ◽

Vol 98 (1) ◽

Author(s):

Carolina A Garcia-Baccino ◽

Daniela A L Lourenco ◽

Stephen Miller ◽

Rodolfo J C Cantet ◽

Zulma G Vitezica

Keyword(s):

Genetic Variation ◽

Beef Cattle ◽

Variance Components ◽

Growth Traits ◽

Ratio Test ◽

Genomic Evaluation ◽

Male Population ◽

Genomic Relationships ◽

Nonadditive Effects ◽

Genomic Model

Abstract Estimates of dominance variance for growth traits in beef cattle based on pedigree data vary considerably across studies, and the proportion of genetic variance explained by dominance deviations remains largely unknown. The potential benefits of including nonadditive genetic effects in the genomic model combined with the increasing availability of large genomic data sets have recently renewed the interest in including nonadditive genetic effects in genomic evaluation models. The availability of genomic information enables the computation of covariance matrices of dominant genomic relationships among animals, similar to matrices of additive genomic relationships, and in a more straightforward manner than the pedigree-based dominance relationship matrix. Data from 19,357 genotyped American Angus males were used to estimate additive and dominant variance components for 3 growth traits: birth weight, weaning weight, and postweaning gain, and to evaluate the benefit of including dominance effects in beef cattle genomic evaluations. Variance components were estimated using 2 models: the first one included only additive effects (MG) and the second one included both additive and dominance effects (MGD). The dominance deviation variance ranged from 3% to 8% of the additive variance for all 3 traits. Gibbs sampling and REML estimates showed good concordance. Goodness of fit of the models was assessed by a likelihood ratio test. For all traits, MG fitted the data as well as MGD as assessed either by the likelihood ratio test or by the Akaike information criterion. Predictive ability of both models was assessed by cross-validation and did not improve when including dominance effects in the model. There was little evidence of nonadditive genetic variation for growth traits in the American Angus male population as only a small proportion of genetic variation was explained by nonadditive effects. A genomic model including the dominance effect did not improve the model fit. Consequently, including nonadditive effects in the genomic evaluation model is not beneficial for growth traits in the American Angus male population.

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