The covariance structure of growth traits in the Afrikaner beef population

Groeneveld, Eildert; Mostert, B.E.; Rust, T.

doi:10.1016/s0301-6226(98)00132-8

Cited by 13 publications

(12 citation statements)

References 14 publications

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“…Direct correlation estimates of post-birth weight traits with PWG was lowest for WW (0.5), higher for W205 and W12 (0.7) and close to unity for W18, while maternal estimates decreased from -0.5 to -0.3 as calf age increased. The direct genetic and maternal genetic correlations (Table 4) were similar to the estimates reported by Groeneveld et al (1998) and Mostert et al (1998), who also noted the very high direct genetic correlation between WW and YW, noting these two traits were closely related. Groeneveld et al (1998) also noted that herd-year-season (HYS) classification resulted in an over-parameterized model (many sub-classes with few observations) resulting in dependencies.…”

Section: Resultssupporting

confidence: 85%

“…The direct genetic and maternal genetic correlations (Table 4) were similar to the estimates reported by Groeneveld et al (1998) and Mostert et al (1998), who also noted the very high direct genetic correlation between WW and YW, noting these two traits were closely related. Groeneveld et al (1998) also noted that herd-year-season (HYS) classification resulted in an over-parameterized model (many sub-classes with few observations) resulting in dependencies. In order to overcome these dependencies while accounting for their importance, HYS was included as a random effect.…”

Section: Resultssupporting

confidence: 85%

“…Relatively large negative directmaternal genetic correlations were indicated for WW and W12. Groeneveld et al (1998) and Mostert et al (1998) report on parameters obtained from a four-trait model used to analyze field data of Afrikaner weights from the National Beef Performance Testing Scheme in South Africa (which did not include possible interactions with sire effects). Direct heritabilities were higher for BW, WW and YW (0.52, 0.23 and 0.17, respectively), but similar for W18 (0.17), while all maternal heritabilities were lower (0.03 to 0.10) and consistently large and negative (-0.5) direct-maternal correlations were shown for all the traits.…”

Section: Resultsmentioning

confidence: 99%

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Long-term selection experiment with Afrikaner cattle 2. Genetic parameters and genotype x environment interaction for calf growth traits

Beffa¹,

Wyk²,

Erasmus³

2009

SA J. An. Sci.

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________________________________________________________________________________ AbstractA selection and line x environment interaction study with grade Afrikaner cattle was established in 1956 at Matopos Research Station, Zimbabwe. Two selection lines of 100 cows each were reared in different management environments. The non-supplemented (NS) line relied on the range throughout the year and was mated to calve with the onset of the rains (December to February). The supplemented (S) line was offered protein-rich supplements during the dry season and mated to calve prior to the onset of the rains (October to December). In 1976, lines were sub-divided into 75 cows each, where one sub-line remained within each environment as a control; the remaining sub-lines were interchanged between environments. Bulls were selected on weaning weight within control lines, while replacement heifers were selected on weight at mating within sub-line. Data recorded over approximately six generations of selection (40 years) was analyzed. The direct heritability estimates were moderate for birth weight (0.4), but low (0.1 to 0.2) for the other traits, similarly maternal heritabilities were low (0.1 to 0.2). Permanent environmental effects due to dam were moderate (0.3) for weights at 205 days, weaning and at 12 months, and was still an important effect at 18 months. Relatively large negative (-0.4) direct-maternal genetic correlations were indicated for weaning and yearling weights. There were indications that all post-weaning weight traits evaluated were closely related giving rise to their joint inclusion in joint multivariate analysis. There were no indications of line x environment interactions, however, interaction of sire x year was important for all the traits highlighting the tremendous year to year variations experienced in the sub-tropics. There is a need to evaluate selection for genotypic stability, particularly for the more extensive farming environments. ________________________________________________________________________________

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Section: Resultssupporting

confidence: 85%

Section: Resultssupporting

confidence: 85%

Section: Resultsmentioning

confidence: 99%

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Long-term selection experiment with Afrikaner cattle 2. Genetic parameters and genotype x environment interaction for calf growth traits

Beffa¹,

Wyk²,

Erasmus³

2009

SA J. An. Sci.

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“…Historically, weaning weight and daily weight gain until weaning have been considered as important components of on farm testing programs, since the weaned calf represents the main source of income for breeders and farmers [12,17,20]. These traits have been used as an indication of the potential for rapid growth of the individual animal and as a measure of the maternal ability of the dam to raise the calf.…”

Section: Introductionmentioning

confidence: 99%

Correction factors for weight productive traits up to weaning in the Bruna dels Pirineus beef cattle breed

Casellas

Piedrafita

2002

Anim. Res.

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-Correction factors for sex of the calf, birth type and age of dam have been calculated regarding birth weight (BW), weaning weight (WW) and average daily weight gain (DWG) in the Bruna dels Pirineus breed. Standard deviations were heterogeneous for the two levels of sex and homogeneous for the two levels of birth type. Therefore, multiplicative correction factors were better for the sex of the calf, whereas additive correction factors were better for birth type. An age of dam correction resulted in either homogeneous (WW and DWG) or heterogeneous (BW) standard deviations depending upon the trait considered. It was observed that in general the additive correction was better, although this correction failed to completely homogenise the standard deviations within the levels of age of the dam for the respective variables. correction factors / beef cattle / productive traits / Bruna dels Pirineus Résumé -Facteurs de correction des caractéristiques de poids jusqu'au sevrage dans la race à viande bovine Bruna dels Pirineus. Les facteurs de correction relatifs au sexe du veau, au type de naissance (simple ou gémellaire) et à l'âge de la mère ont été calculés pour ce qui concerne le poids à la naissance (BW), le poids au sevrage (WW) et le gain de poids moyen quotidien (DWG) dans la race Bruna dels Pirineus. Les écarts types ont été hétérogènes pour les deux niveaux correspondant au sexe, et homogènes pour les deux niveaux correspondant au type de naissance. Par conséquent, les facteurs de correction multiplicatifs ont été meilleurs pour le sexe du veau, tandis que les facteurs de correction additifs ont été meilleurs pour le type de naissance. La correction prenant en compte l'âge de la mère a entraîné des écarts types homogènes (WW et DWG) ou hétérogènes (BW). En général, la correction additive a été meilleure, bien que cette correction n'ait pas rendu complètement homogène les écarts types dans les niveaux d'âge de la mère pour les variables étudiées.

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“…Maternal effects are present in a number of traits, especially for those which are expressed prior to weaning, in beef cattle populations. Direct and maternal additive components are assumed to be genetically correlated ( Meyer 1992a; Shi et al 1993; Robinson 1996a; Groeneveld et al 1998). Van Vleck (1990)extended the genetic grouping theory to accommodate maternal effects.…”

Section: Introductionmentioning

confidence: 99%

Effects of genetic groups on estimates of variance components for a maternally influenced trait in the Spanish Limousine

Díaz¹,

Mínguez²,

Carabaño³

2002

J Animal Breeding Genetics

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Summary Residual maximum likelihood (REML) estimates of variance components for standardized 210‐day weights were obtained in the Limousine breed from Spain under different animal models. All models were applied including (Gdm) or not (G00) genetic groups for the direct and the maternal components. Genetic groups were defined according to sex of progenitor and generation in two different approaches depending on whether the full pedigree information or reduced pedigree was used. For the most complex model, which included direct, maternal and permanent environmental variances as well as the direct–maternal covariance, genetic groups were imposed either to the direct (Gd0) or to the maternal (G0m) component treating genetic groups as covariates without the QP transformation. For the Gdm case (genetic groups for both direct and maternal effects) with the full pedigree information, the estimates of the direct genetic variance and the genetic covariance between direct and maternal genetic effects showed the largest reduction, while the estimate of maternal genetic variance was only slightly reduced, with respect to G00, a model without genetic groups. This result might be due to a less important variability among group effects for the maternal component, probably due to a lower selection intensity performed for this component. However, for the Gd0 case, estimates of genetic variances and especially the direct–maternal covariance were largely overestimated with respect to the Gdm case. Inclusion of direct and maternal grouping was deemed necessary for this population. Reduction of pedigree information did not seem to have a large impact on variance component estimation. Nevertheless, deeper pedigree information together with a correct definition of the generation to assign genetic groups is needed to accommodate the effect of selection on direct and maternal components of this trait, in this population.

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The covariance structure of growth traits in the Afrikaner beef population

Cited by 13 publications

References 14 publications

Long-term selection experiment with Afrikaner cattle 2. Genetic parameters and genotype x environment interaction for calf growth traits

Long-term selection experiment with Afrikaner cattle 2. Genetic parameters and genotype x environment interaction for calf growth traits

Correction factors for weight productive traits up to weaning in the Bruna dels Pirineus beef cattle breed

Effects of genetic groups on estimates of variance components for a maternally influenced trait in the Spanish Limousine

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