Variance components due to direct and maternal effects and estimation of breeding values for 12-week weight of Welsh Mountain lambs

Saatcı, Mustafa; Dewi, I. Ap; Ulutaş, Zafer

doi:10.1017/s1357729800050918

Cited by 27 publications

(21 citation statements)

References 19 publications

(10 reference statements)

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“…Models 3 and 4, which included the additive maternal effect but not the maternal environmental effect, yielded smaller estimates of σ a 2 and h 2 d than did Models 1 and 2. The same result was found in previous reports which compared models for various goat and sheep breeds (Saatci et al, 1999;Ligda et al, 2000;Szwaczkowski et al, 2006;Roy et al, 2008). Meyer (1992) showed that models not accounting for maternal genetic effects could result in substantially higher estimates of additive direct genetic variance and, therefore, higher estimates of h 2 d .…”

Section: Resultssupporting

confidence: 87%

Genetic parameter estimates for birth and weaning weights in Raeini goats

Gholizadeh¹,

Mlanji²,

Hashemi³

et al. 2010

CZECH J ANIM SCI

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AbstRAct:The aim of the present study was to estimate variance components and genetic parameters for birth and weaning weights in Raeini goats. The data were collected from the Breeding Centre of Raeini (BCR) cashmere goats in Kerman province of Iran from 1986 to 2008. Random effects included direct and maternal additive genetic effects, maternal permanent environmental effects with direct-maternal genetic covariance and random residual effects. Variance and covariance components and genetic parameters were estimated using the DFREML program by fitting six single-trait animal models. Depending on the model, h d 2 varied from 0.057 to 0.323 for birth weight and from 0.043 to 0.229 for weaning weight. Estimates of m 2 ranged from 0.016 to 0.289 for birth weight and from 0.01 to 0.184 for weaning weight. The maternal permanent environmental effect was significant for both traits and ignoring maternal effects in the model caused the overestimation of direct heritability.

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Section: Resultssupporting

confidence: 87%

Genetic parameter estimates for birth and weaning weights in Raeini goats

Gholizadeh¹,

Mlanji²,

Hashemi³

et al. 2010

CZECH J ANIM SCI

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“…These reductions in, especially, σ 2 e were significant and amounts to 41% and 25% respectively for birth and weaning weight (not presented), indicating that some of the temporary environmental variance has been attributed to σ 2 e and some to σ 2 pe when c 2 te was not fitted. Similar general patterns were reported by Maniatis & Pollot (2002) for 8-week weight in Suffolk sheep and Saatci et al, (1999) for 12-week weight in Welsh mountain sheep. According to Al-Shorepy & Notter (1998) these effects include not only common environmental effects unique to the litter but also non-additive genetic effects expressed in full-sibs and genotype x year interaction effects expressed in the dam.…”

Section: Resultssupporting

confidence: 85%

Revised models and genetic parameter estimates for production and reproduction traits in the Elsenburg Dormer sheep stud

Wyk¹,

Fair²,

Cloete³

2004

SA J. An. Sci.

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Genetic parameters for production and reproduction traits in the Elsenburg Dormer sheep stud were estimated using records of 11743 lambs born between 1943 and 2002. An animal model with direct and maternal additive, maternal permanent and temporary environmental effects was fitted for traits considered traits of the lamb (birth and weaning weight and survival). Fixed effects were sex, birth status, year and age of dam. Weaning weights were pre-adjusted to a 100-day equivalent. For reproduction traits (considered as traits of the ewe), which included number and weight of lambs born and weaned, repeatability models were fitted. The random part consisted of direct additive and ewe and sire permanent environmental effects. Direct and maternal heritability estimates were 0.13 and 0.23 for birth weight and 0.07 and 0.09 for weaning weight. Corresponding proportions of total phenotypic variance due to maternal permanent and temporary environment were 0.09 and 0.28 and 0.06 and 0.22 respectively. The genetic correlation between animal effects was -0.23 in the case of birth weight. The results showed that temporary environment (full sibs within a year) generally has a major effect on all pre-weaning traits. The direct heritability estimate of survival was 0.02 while the temporary maternal environmental variance as a proportion of phenotypic variance was 0.10. The estimates obtained for number and weight of lambs born and weaned were generally low, ranging from 0.03 for number of lambs born to 0.11 for total weight at birth. The permanent environmental effect of the ewe accounted for 6-7% of the total phenotypic variance. Genetic correlations of total weight of lamb weaned with the other reproduction traits were generally high (0.64 to 0.92) with low standard errors. The corresponding phenotypic, environmental and ewe permanent environmental correlations were all medium to high and estimated with a fair deal of accuracy according to low standard errors. The genetic relationship between weaning weight of the ewe and her lifetime reproduction (accumulated over four lambing chances) ranged between 0.40 and 0.67. Correlations between number of lambs weaned per ewe and weight of lamb weaned per ewe were particularly high (0.8 -0.9). It was concluded that the maternal environmental effect should be partitioned into two components (permanent and temporary) when data sets involving multiple births over many generations are considered.

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“…Maternal heritability decreased with age, which confirms the proposal by Robison (1981) that maternal effects in mammals are substantial in young animals but diminish with age. Maternal heritability estimates of birth and weaning weights in this study were higher than values reported by Maria et al (1993), Snyman et al (1995), Yazdi et al (1997), Saatci et al (1999), Ligda et al (2000), Neser et al (2001), and Ekiz et al (2004) for several sheep breeds. The high estimates of maternal heritability for 9-month and yearling weights were unexpected because at these ages individuals do not depend on their mother and their weights should reflect only the direct effect of the genes on growth except for carry over maternal effects from before weaning.…”

Section: Resultscontrasting

confidence: 81%

Estimates of genetic parameters for growth traits in Kermani sheep

Behzadi

Shahroudi

Vleck

2007

J Animal Breeding Genetics

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Summary Birth weight (BW), weaning weight (WW), 6‐month weight (W6), 9‐month weight (W9) and yearling weight (YW) of Kermani lambs were used to estimate genetic parameters. The data were collected from Shahrbabak Sheep Breeding Research Station in Iran during the period of 1993–1998. The fixed effects in the model were lambing year, sex, type of birth and age of dam. Number of days between birth date and the date of obtaining measurement of each record was used as a covariate. Estimates of (co)variance components and genetic parameters were obtained by restricted maximum likelihood, using single and two‐trait animal models. Based on the most appropriate fitted model, direct and maternal heritabilities of BW, WW, W6, W9 and YW were estimated to be 0.10 ± 0.06 and 0.27 ± 0.04, 0.22 ± 0.09 and 0.19 ± 0.05, 0.09 ± 0.06 and 0.25 ± 0.04, 0.13 ± 0.08 and 0.18 ± 0.05, and 0.14 ± 0.08 and 0.14 ± 0.06 respectively. Direct and maternal genetic correlations between the lamb weights varied between 0.66 and 0.99, and 0.11 and 0.99. The results showed that the maternal influence on lamb weights decreased with age at measurement. Ignoring maternal effects in the model caused overestimation of direct heritability. Maternal effects are significant sources of variation for growth traits and ignoring maternal effects in the model would cause inaccurate genetic evaluation of lambs.

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Variance components due to direct and maternal effects and estimation of breeding values for 12-week weight of Welsh Mountain lambs

Cited by 27 publications

References 19 publications

Genetic parameter estimates for birth and weaning weights in Raeini goats

Genetic parameter estimates for birth and weaning weights in Raeini goats

Revised models and genetic parameter estimates for production and reproduction traits in the Elsenburg Dormer sheep stud

Estimates of genetic parameters for growth traits in Kermani sheep

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