Genetic parameter estimates in Sabi sheep

Matika, Oswald; Wyk, JB van; Erasmus, G.J.; Baker, R. L.

doi:10.1016/s0301-6226(02)00129-x

Cited by 134 publications

(113 citation statements)

References 45 publications

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“…The estimate obtained in the present study (0.02), although non significant (i.e. at a level of two times the corresponding standard error), accords well with literature values which vary between 0.00 and 0.09 (Olivier et al, 1998;Snyman et al, 1998;Cloete et al, 2001;Matika et al, 2003). Lamb survival is a complex trait influenced by the lamb's own ability to survive and by its dam's rearing ability (Burfening, 1993).…”

Section: Resultssupporting

confidence: 90%

“…Estimates of the present study of 0.13 for h², 0.22 for m² and 0.09 for c² pe generally accords well with the range of literature values cited above. Corresponding estimates for weaning weight were 0.07, 0.08 and 0.07 respectively, which are in accordance with those of Boujenane & Kansari (2002) and are within the range of other literature values (0.06 to 0.39) (Cloete et al, 2001;Matika et al, 2003).…”

Section: Resultssupporting

confidence: 89%

“…Parameter estimates fitting most appropriate models for production traits and survival (lamb traits) are presented in Table 4. In the case of birth weight, genetic parameters obtained from a wide range of sheep breeds ranged from 0.07 to 0.23 for h², 0.07 to 0.30 for m² and from 0.08 to 0.25 for c² pe (Matika et al, 2003). Estimates of the present study of 0.13 for h², 0.22 for m² and 0.09 for c² pe generally accords well with the range of literature values cited above.…”

Section: Resultssupporting

confidence: 87%

“…In the present study the genetic correlation between direct and maternal effects (r am ) was -0.23 for birth weight. The estimate was intermediate compared to other literature values (-0.63 to +0.52) when fitting the same model without temporary environment (Matika et al, 2003). The estimate is lower than that of -0.35 found by Van Wyk et al (1993b) Dormer, using part of the same data set.…”

Section: Resultscontrasting

confidence: 80%

“…Literature estimates, using different models and breeds, indicated that σ 2 pe accounted for 8 to 19% of the total phenotypic variance in weaning weight (Matika et al, 2003). The estimate of the current study is lower than some literature estimates and can be attributed to the inclusion of c 2 te in the model.…”

Section: Resultscontrasting

confidence: 73%

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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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Section: Resultssupporting

confidence: 90%

Section: Resultssupporting

confidence: 89%

Section: Resultssupporting

confidence: 87%

Section: Resultscontrasting

confidence: 80%

Section: Resultscontrasting

confidence: 73%

See 3 more Smart Citations

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 analysis of growth rate and Kleiber ratio in Zandi sheep

Ghafouri‐Kesbi

Abbasi

Afraz

et al. 2011

Trop Anim Health Prod

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Genetic parameters for average daily gain from birth to weaning (ADGa), birth to 6 months (ADGb), weaning to 6 months (ADGc), weaning to yearling age (ADGd), and corresponding Kleiber ratios (KRa, KRb, KRc, and KRd) were estimated by using records of 3,533 Zandi lambs, descendent of 163 sires and 1265 dams, born between 1991 and 2005 at the Zandi Sheep Breeding Station at Khojir National Park, Tehran, Iran. A derivative-free algorithm combined with a series of six single-trait linear animal models was used to estimate phenotypic variance and its direct, maternal, and residual components. In addition, bivariate analyses were done to estimate (co)variance components between traits. Estimates of direct heritability (h(2)) were 0.11, 0.15, 0.09, 0.10, 0.10, 0.10, 0.06, and 0.07 for ADGa, ADGb, ADGc, ADGd, KRa, KRb, KRc, and KRd, respectively, thereby indicating the presence of low additive genetic variation for growth rate and Kleiber ratio in this population of Zandi sheep. Maternal genetic component was found to be significant on ADGa and KRa and contributed 3% and 5%, respectively, in total phenotypic variance of ADGa and KRa. A widespread range of genetic correlations among traits studied was observed. Except for negative genetic correlations between ADGa and KRc, ADGa and KRd, and between KRa and KRc, in other cases, genetic correlations were positive and moderate to very high. Phenotypic correlations ranged from -0.49 (ADGa/KRd) to 0.94 (ADGc/KRc). These results indicate that selecting for improved growth rate or Kleiber ratio in Zandi sheep would generate a relatively slow genetic progress.

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The Damara in the context of Southern Africa fat-tailed sheep breeds

Almeida

2011

Trop Anim Health Prod

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Sheep production is one of the most important activities in animal production in tropical regions. Southern Africa (SA) fat-tailed sheep such as the Afrikaner, Namaqua Afrikaner, Nguni, Persian Black Head, Tswana, Pedi, Sabi, and particularly the Damara are important animal genetic resources very well adapted to their harsh home environments. In this review, autochthonous sheep genetic resources of SA are reviewed regarding history and productive performance. A special focus is made to the most internationalized of such breeds: the Damara. The following aspects are reviewed: history, standards, productive performance in SA, and importation to Australia. Finally, a reference is made to the influence of fat-tailed sheep formation of composite breeds such as the Dorper or the Meatmaster.

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Genetic parameter estimates in Sabi sheep

Cited by 134 publications

References 45 publications

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

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

Genetic analysis of growth rate and Kleiber ratio in Zandi sheep

The Damara in the context of Southern Africa fat-tailed sheep breeds

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