Genetic parameters for growth traits for a composite terminal sire breed of sheep.

Mousa, E.; Vleck, L.D. Van; Leymaster, K. A.

doi:10.2527/1999.7771659x

Cited by 67 publications

(46 citation statements)

References 23 publications

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“…Selecting for either birth weight or weaning weight without changing ewe weight would be difficult. This is in agreement with other reports (Nasholm & Danell, 1996;Yazdi et al, 1997;Mousa et al, 1999).…”

Section: Resultssupporting

confidence: 94%

Phenotypic and genetic relationships between lamb and ewe traits for the Sabi sheep of Zimbabwe

Matika¹,

Wyk²,

Erasmus³

et al. 2001

SA J. An. Sci.

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Genetic and phenotypic correlations were estimated between lamb and ewe traits in a flock of Sabi sheep reared at the Matopos Research Station. Direct additive estimates of heritability were: 0.28 ± 0.04; 0.17 ± 0.00; 0.25 ± 0.01; 0.39 ± 0.01; 0.59 ± 0.01; 0.50 ± 0.01; 0.68 ± 0.03; 0.12 ± 0.003; 0.25 ± 0.01; 0.11 ± 0.00; 0.12 ± 0.00; for birth weight, weaning weight (120 days), 12 month weight, 18 month weight, ewe mating weight, post partum weight, ewe weight at weaning of lamb, total weight of lamb weaned, slaughter weight, hot and cold carcass weights respectively. Genetic correlations between birth weight and other weights to 18 months were high (0.75-0.85), whilst the relationship between weaning, 12 month and 18 month weight was close to unity. The genetic correlation between birth weight and ewe weights (mating, post-partum and dam weight at weaning of lamb) were moderate viz. 0.51 ± 0.08, 0.40 ± 0.09, 0.49 ± 0.07 respectively and were close to unity at 18 months of age viz. 0.96 ± 0.02, 0.92 ± 0.03, and 0.84 ± 0.03 respectively. Total weight of lamb weaned was moderately correlated to birth weight (r g = 0.46 ± 0.15) but tended to be highly correlated with 18 month weight (0.92 ± 0.10) and ewe weights (0.75 ± 0.09-0.91 ± 0.07). The genetic correlation between birth weight and slaughter and carcass weight was moderate and was high at 18 months. The heritability estimates from a univariate logit transformed analysis for fertility, prolificacy and lamb survival were 0.08 ± 0.04, 0.22 ± 0.03, and 0.01 ± 0.02 respectively. The genetic correlation between fertility and lamb weight and ewe weights was low (-0.08 ± 0.004, to 0.06 ± 0.02) and some estimates had large standard errors. The genetic correlation between prolificacy and birth weight was close to zero. The genetic correlations between prolificacy and weaning weight, 12 month weight, 18 month weight, ewe mating, post-partum and ewe weight at weaning were 0.07 ± 0.02; 0.12 ± 0.00; 0.07 ± 0.02; 0.22 ± 0.00; 0.13 ± 0.00; 0.24 ± 0.00 respectively, and that between fertility and prolificacy was negative (-0.17 ± 0.07). Genetic correlations between lamb survival and birth weight, weaning weight, 12 month weight, 18 month weight and total weight of lamb weaned were 0.18 ± 0.00, 0.26 ± 0.00, 0.15 ± 0.00, 0.15 ± 0.00, 0.13 ± 0.00 respectively. Selection for birth weight and total weight of lamb weaned have possible uses in a selection index for the Sabi flock. _______________________________________________________________________________________

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Section: Resultssupporting

confidence: 94%

Phenotypic and genetic relationships between lamb and ewe traits for the Sabi sheep of Zimbabwe

Matika¹,

Wyk²,

Erasmus³

et al. 2001

SA J. An. Sci.

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“…The low heritability estimate for BWT in Bharat Merino sheep may be attributed to the general poor nutritional level of ewes giving a leeway for large environmental variation. Our h 2 estimate for BWT was within the range of earlier reported estimates by Conington et al (1995), Nasholm and Danell (1996), Mousa et al (1999), Janssens et al (2000) and Mandal et al (2006b). Higher estimate of heritability for BWT (0.23) in Bharat Merino sheep was reported by Dixit et al (2001), by paternal half-sib method for the data over the years 1982 to 1996.…”

Section: Resultssupporting

confidence: 86%

Estimates of (co)variance components and genetic parameters for body weights and first greasy fleece weight in Bharat Merino sheep

Gowane

Chopra

Prince

et al. 2010

Animal

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(Co)variance components and genetic parameters of weight at birth (BWT), weaning (3WT), 6, 9 and 12 months of age (6WT, 9WT and 12WT, respectively) and first greasy fleece weight (GFW) of Bharat Merino sheep, maintained at Central Sheep and Wool Research Institute, Avikanagar, Rajasthan, India, were estimated by restricted maximum likelihood, fitting six animal models with various combinations of direct and maternal effects. Data were collected over a period of 10 years (1998 to 2007). A log-likelihood ratio test was used to select the most appropriate univariate model for each trait, which was subsequently used in bivariate analysis. Heritability estimates for BWT, 3WT, 6WT, 9WT and 12WT and first GFW were 0.05 6 0.03, 0.04 6 0.02, 0.00, 0.03 6 0.03, 0.09 6 0.05 and 0.05 6 0.03, respectively. There was no evidence for the maternal genetic effect on the traits under study. Maternal permanent environmental effect contributed 19% for BWT and 6% to 11% from 3WT to 9WT and 11% for first GFW. Maternal permanent environmental effect on the post-3WT was a carryover effect of maternal influences during pre-weaning age. A low rate of genetic progress seems possible in the flock through selection. Direct genetic correlations between body weight traits were positive and ranged from 0.36 between BWT and 6WT to 0.94 between 3WT and 6WT and between 6WT and 12WT. Genetic correlations of 3WT with 6WT, 9WT and 12WT were high and positive (0.94, 0.93 and 0.93, respectively), suggesting that genetic gain in post-3WT will be maintained if selection age is reduced to 3 months. The genetic correlations of GFW with live weights were 0.01, 0.16, 0.18, 0.40 and 0.32 for BWT, 3WT, 6WT, 9WT and 12WT, respectively. Correlations of permanent environmental effects of the dam across different traits were high and positive for all the traits (0.45 to 0.98).

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“…Estimates of direct heritability obtained in this study for the other traits were generally small, but still fell within the ranges of previously reported estimates, which ranged from 0.03 to 0.37 for WWT (Notter, 1998;Lewis and Beatson, 1999;Mousa et al, 1999), from 0.14 to 0.55 for later BW (Notter, 1998;Lewis and Beatson, 1999;Jones et al, 2004), and from 0.27 to 0.44 for FD and MD (Roden et al, 2003;Jones et al, 2004). Conversely, the maternal heritability estimates for BWT and WWT reported here were greater than those reported in the literature, where estimates ranged from 0.17 to 0.24 for BWT (Mousa et al, 1999) and from 0.04 to 0.15 for WWT (Notter, 1998;Lewis and Beatson, 1999).…”

Section: Discussionsupporting

confidence: 89%

Prediction of prion protein genotype and association of this genotype with lamb performance traits of Suffolk sheep1,2

Sawalha

Villanueva

Brotherstone

et al. 2010

Journal of Animal Science

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ABSTRACT:The association of the prion protein (PrP) gene with susceptibility to scrapie has formed the basis of selection programs aimed at eradicating the disease from sheep populations. Animals are genotyped for the PrP gene and those with the less susceptible genotypes are selected. The objectives of this study were to determine the effectiveness of predicting PrP genotypes by using information from relatives and to investigate the association of the PrP genotype with lamb performance traits in Suffolk sheep. Data were obtained from a scrapie-affected flock maintained in Scotland. A total of 643 were animals genotyped at codon 171 of the PrP gene with 2 alleles, R and Q. The genotypes of these animals were used to predict the genotypes of 5,173 nongenotyped animals in the same flock using segregation analysis. The genotype of nongenotyped animals was predicted from the probabilities for each possible genotype; further, an overall index for each animal was calculated to reflect the accuracy of prediction. Association analyses of the PrP gene (using animals with both known and inferred genotypes) with BW at birth, at weaning (56 d), and at 150 d, and for backfat and muscle depths at 150 d of age were carried out. A linear mixed model with random direct and maternal additive genetic effects, maternal permanent and temporary environmental effects, and year of birth was tested, and the most appropriate model was used for each trait. The expected number of Q alleles carried (from 0 to 2) by each animal was calculated and used in the model as a linear and quadratic covariate to test for associations with possible additive and dominance PrP gene effects, respectively. Results showed that the genotypes of relatively few animals (235) were inferred with certainty (compared with the 5,173 nongenotyped animals). Approximately 25% of the 5,173 predicted genotypes were inferred with a genotype probability index of 50% and greater. There was no significant association of the PrP gene with any of the performance traits studied (there were no significant additive or dominance effects). Such was the case whether data on animals with known or with both known and predicted genotypes were considered. It can be concluded that selection for PrPresistant alleles in Suffolk sheep is unlikely to affect performance directly.

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Genetic parameters for growth traits for a composite terminal sire breed of sheep.

Cited by 67 publications

References 23 publications

Phenotypic and genetic relationships between lamb and ewe traits for the Sabi sheep of Zimbabwe

Phenotypic and genetic relationships between lamb and ewe traits for the Sabi sheep of Zimbabwe

Estimates of (co)variance components and genetic parameters for body weights and first greasy fleece weight in Bharat Merino sheep

Prediction of prion protein genotype and association of this genotype with lamb performance traits of Suffolk sheep1,2

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