Genetic trends for lamb weights in flocks of Egyptian Rahmani and Ossimi sheep

Shaat, I.; Galal, Salah; Hussein, M. A.

doi:10.1016/s0921-4488(03)00185-8

Cited by 38 publications

(28 citation statements)

References 6 publications

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“…The genetic trends for 3 months weight (34 g/year) and 6 months weight (28 g/year), were greater than the ones observed by Dorostkar et al (2011) in Moghani sheep (5.3 and 5.2 g/year, respectively), and Lotfi et al (2011) in Arman sheep (7 and 8 g/year, respectively); however they were lower than that ones reported by Hassani et al (2010) in Baluchi sheep (55 and 72 g/year, respectively), Shaat et al (2004) in Rahmani sheep (92 and 135 g/year, respectively), and Bahreini and Aslaminejad (2010) in Kermani sheep (82 and 76 g/year, respectively). The estimation of direct genetic trend for yearling weight (24 g/year) was lower than those reported by Hassani et al (2010) in Baluchi sheep (88 g/year) and Dorostkar et al (2011) in Moghani sheep(84 g/year), while it was in accordance with the findings of Shrestha et al (1996) in Suffolk sheep (23 g/year) and it was higher than the ones reported by Bahreini and Aslaminejad (2010) in Kermani sheep (16 g/year).…”

Section: Body Weight Traitscontrasting

confidence: 56%

Study of the environmental, genetic and phenotypic trends for pelt traits and body weight traits in Zandi sheep

Khojastehkey

Aslaminejad

2013

Journal of Applied Animal Research

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In this study, the data of body weights and pelt records of Zandi sheep kept at the Khojir national park breeding station of Iran were used to estimate phenotypic, genetic and environmental trends for birth weight (BW), 3 months weight (3MW), 6 months weight (6MW), yearling weight (YW), curl type (CT), pattern score (PS) and Luster (Lu) of pelt. Data were analyzed for each trait using derivative-free REML procedures under a univariate animal model. Genetic, phenotypic and environmental trends were estimated by regression of the estimated mean of breeding values, phenotypic mean and difference between estimated mean of breeding values and phenotypic mean on birth year, respectively. The average additive direct genetic trends for BW, 3MW, 6MW, YW were 0.00190.001, 0.03490.004, 0.02890.007 and 0.02490.004 g/year and for CT, PS and Lu were 0.0069.002, 0.00190.002 and 0.00290.004, respectively. Although selection for body weight traits was effective and significant genetic improvements were obtained, limited genetic improvement in the pelt traits were detected.

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Section: Body Weight Traitscontrasting

confidence: 56%

Study of the environmental, genetic and phenotypic trends for pelt traits and body weight traits in Zandi sheep

Khojastehkey

Aslaminejad

2013

Journal of Applied Animal Research

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“…For example, the additive genetic correlation is 0.60 between BW and WW, falling slightly to 0.31 between BW and W9. This result is expected because an autocorrelation would exist among the genetic and environmental effects associated with the measurements (Shaat et al 2004). A result which has been frequently reported by different researchers (e.g., Abegaz et al 2005, Miraei-Ashtiani et al 2007, Eskandarinasab et al 2010 is the negative phenotypic correlation between pre-and post-weaning daily gain in spite of positive genetic correlation.…”

Section: Resultsmentioning

confidence: 62%

Genetic parameters for direct and maternal effects on growth traits of sheep

Ghafouri‐Kesbi

Baneh

2012

Arch. Anim. Breed.

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The aim of the present study was to estimate (co)variance components and corresponding genetic parameters for birth weight (BW), weaning weight (WW), 6-month weight (W6), 9-month weight (W9), average daily gain from birth to weaning (WWDG), average daily gain from weaning to 6 months (W6DG) and average daily gain from 6 months to 9 months (W9DG) for a nucleus flock of Iranian Makooei sheep. Genetic parameters were estimated by REML procedure fitting six animal models including various combinations of maternal effects. The Akaike information criterion (AIC) was used to determine the most appropriate model. Estimates of direct heritability (h 2 ) ranged from 0.13 (W6DG) to 0.32 (BW). Maternal effects were found to be important in the growth performance of the Makooei sheep, indicating the necessity of including maternal effects in the model to obtain accurate estimates of direct heritability. Estimates of maternal heritability (m 2 ) ranged from 0.05 (W6) to 0.16 (WWDG) and the estimates of proportion of maternal permanent environmental variance to phenotypic variance (c 2 ) were in the range between 0.05 (BW) and 0.10 (W6). Direct additive genetic correlations were positive in all cases and ranged from 0.00 (BW/W9DG) to 0.99 (WW/WWDG). Phenotypic correlations showed a broad range from −0.27 (WW/W9DG) to 0.99 (WW/WWDG). Estimates of genetic parameters showed that genetic improvement through selection programs is possible. WW would be a suitable selection criterion since it has acceptable direct heritability and relatively high genetic correlation with other traits.

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“…A higher litter size allows more selection pressure on other economically important traits [22]. Because the heritability of LS is usually low, a selection on phenotype will be quite ineffective in improving litter size.…”

Section: Introductionmentioning

confidence: 99%

Genetic parameters for litter size in sheep: natural versus hormone-induced oestrus

2004

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-The litter size in Suffolk and Texel-sheep was analysed using REML and Bayesian methods. Litters born after hormonal induced oestrus and after natural oestrus were treated as different traits in order to estimate the genetic correlation between the traits. Explanatory variables were the age of the ewe at lambing, period of lambing, a year*flock-effect, a permanent environmental effect associated with the ewe, and the additive genetic effect. The heritability estimates for litter size ranged from 0.06 to 0.13 using REML in bi-variate linear models. sheep / litter size / oestrus induction / heritability / genetic correlation

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Genetic trends for lamb weights in flocks of Egyptian Rahmani and Ossimi sheep

Cited by 38 publications

References 6 publications

Study of the environmental, genetic and phenotypic trends for pelt traits and body weight traits in Zandi sheep

Study of the environmental, genetic and phenotypic trends for pelt traits and body weight traits in Zandi sheep

Genetic parameters for direct and maternal effects on growth traits of sheep

Genetic parameters for litter size in sheep: natural versus hormone-induced oestrus

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