Genetic parameter estimates for lamb growth traits and greasy fleece weight at first shearing in Turkish Merino sheep

Özcan, Mustafa; Ekiz, Bülent; Yılmaz, Alper; Ceyhan, Ayhan

doi:10.1016/j.smallrumres.2004.06.009

Cited by 66 publications

(71 citation statements)

References 21 publications

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“…Further, our estimate of the proportion of variance associated with permanent environmental maternal effects for weaning weight (c 2 00.15) was similar to the reported estimates of Rashidi et al (2008) in Kermani sheep (0.13), Tosh and Kemp (1994) in Romanov sheep (0.12), and Mandal et al (2008) in Muzaffarnagari sheep (0.10). Lower estimates were reported by Abegaz et al (2005) in Horro sheep (0.06), Ozcan et al (2005) in Merino sheep (0.08), and Matika et al (2003) in Sabi sheep (0.07) as compared to the present findings. However, the estimate of 0.23 in Poly pay (Notter 1998) was higher than our estimate.…”

Section: Weaning Weightcontrasting

confidence: 94%

“…The estimate of the direct heritability of weaning weight in the present study (0.14, model 5) was similar to the findings of Snyman et al (1995), Abegaz et al (2002), Matika et al (2003), and Ozcan et al (2005) in different breeds of sheep. However, higher heritability estimates for weaning weight as compared to those from the present study were reported by other workers in various sheep breeds (Snyman et al 1995;Notter 1998;El Fadili et al 2000;Assan et al 2002;Gizaw et al 2007), and lower heritabilities for this trait were reported by Notter (1998) in Polypay sheep (0.07) and Ekiz et al (2004) in Turkish Merino sheep (0.06).…”

Section: Weaning Weightsupporting

confidence: 89%

“…The estimate of maternal heritability for weaning weight from our data (m 2 00.05) was within the range of reported estimates for other sheep breeds (Yazdi et al 1997;Notter 1998;Ozcan et al 2005;Mandal et al 2008;Miraei-Ashtiani et al 2007). However, El Fadili et al (2000), Abegaz et al (2002), Safari et al (2005), and Savar-Sofla et al (2011) obtained higher estimates (0.10Á0.24) than the present study.…”

Section: Weaning Weightsupporting

confidence: 86%

“…In addition, effects of litter size are probably explained by the competition for uterine space and capacity during pregnancy and for milk before weaning among multiple-born lambs Baneh et al 2010). Significant effect of various environmental factors on body weight have been reported in several breeds of sheep (EftekhariShahroudi et al 2002;Ozcan et al 2005;Rashidi et al 2008;Baneh et al 2010). …”

Section: Environmental Effectsmentioning

confidence: 99%

“…Nasholm and Danell (1994) observed that when maternal genetic effects are important, but not considered in the statistical model, heritability estimates are biased upward and the realized efficiency of selection is reduced. A number of studies have demonstrated that maternal effects are substantial for growth-related traits in sheep and the inclusion of maternal effects in animal models has an important effect on the estimates of direct heritability (Maria et al 1993;Ozcan et al 2005;Mandal et al 2006;Rashidi et al 2008;Baneh et al 2010). Genetic and environmental relationships between direct and maternal effects for growth have often varied from moderately positive to highly negative in various sheep breeds (Maria et al 1993;Tosh & Kemp 1994;Snyman et al 1995;Nasholm & Danell 1996;Yazdi et al 1997;Notter 1998).…”

Section: Introductionmentioning

confidence: 99%

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Genetic parameter estimates for growth traits in Iran-Black sheep

Kamjoo

Baneh

Yousefi

et al. 2013

Journal of Applied Animal Research

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The present study was conducted to estimate variance components and genetic parameters for growth traits of Iran-Black sheep, maintained at the Abbasabad sheep breeding station, located in northeast of Mashhad, (Razavi Khorasan province of Iran) over a period of 24 years (1981 through 2004). Records of 4607 lambs descended from 155 rams, and 1227 ewes were used in the study. Traits included for the present study were birth weight (BW), weaning weight (WW), weight at 6 months (W6), weight at 9 months (W9), and yearling weight (YW). Analyses were carried out by restricted maximum likelihood (REML) fitting an animal model and ignoring or including maternal genetic or permanent environmental effects. Six different animal models were fitted for all traits. The most appropriate model was chosen after testing the improvement of the log-likelihood values. Heritability estimates for weight at birth; weaning; and 6, 9, and 12 months of age were 0.04, 0.14, 0.16, 0.19, and 0.18, respectively. Maternal heritability of body weight declined from 0.33 at birth to 0.04 at six months of age. The maternal permanent environmental component accounted for 6% to 15% to the total variance for all traits under study. The direct-maternal genetic correlation (r am ) was positive for all traits and ranged from 0.3690.27 for BW to 0.9990.98 for YW, but was never significant. The results showed that modest rates of genetic progress appear possible for all weights. Results also suggest that maternal additive effects were only important in early stages of growth, whereas a permanent environmental maternal effect existed at all ages up to 12 months of age, probably as a carry-over effect of maternal influences present at weaning. Direct genetic correlations (r a1,a2 ) between traits were positive and ranged from 0.82 (BW-WW) to 0.99 (W6-YW). The estimates of correlation between permanent environmental maternal effect among traits were close to those of r a1,a2 . Phenotypic and environmental correlations for all traits were generally lower than direct genetic correlations.

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Section: Weaning Weightcontrasting

confidence: 94%

Section: Weaning Weightsupporting

confidence: 89%

Section: Weaning Weightsupporting

confidence: 86%

Section: Environmental Effectsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Genetic parameter estimates for growth traits in Iran-Black sheep

Kamjoo

Baneh

Yousefi

et al. 2013

Journal of Applied Animal Research

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Estimates of (co)variance components and genetic parameters for growth traits of Avikalin sheep

Prince

Gowane

Chopra

et al. 2010

Trop Anim Health Prod

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(Co)variance components and genetic parameters for various growth traits of Avikalin 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. Records of 3,840 animals descended from 257 sires and 1,194 dams were taken for this study over a period of 32 years (1977-2008). Direct heritability estimates (from best model as per likelihood ratio test) for weight at birth, weaning, 6 and 12 months of age, and average daily gain from birth to weaning, weaning to 6 months, and 6 to 12 months were 0.28 +/- 0.03, 0.20 +/- 0.03, 0.28 +/- 0.07, 0.15 +/- 0.04, 0.21 +/- 0.03, 0.16 and 0.03 +/- 0.03, respectively. Maternal heritability for traits declined as animal grows older and it was not at all evident at adult age and for post-weaning daily gain. Maternal permanent environmental effect (c(2)) declined significantly with advancement of age of animal. A small effect of c(2) on post-weaning weights was probably a carryover effect of pre-weaning maternal influence. A significant large negative genetic correlation was observed between direct and maternal genetic effects for all the traits, indicating antagonistic pleiotropy, which needs special care while formulating breeding plans. A fair rate of genetic progress seems possible in the flock by selection for all traits, but direct and maternal genetic correlation needs to be taken in to consideration.

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Estimates of (co)variance components and genetic parameters for growth traits in Sirohi goat

Gowane

Chopra

Prakash

et al. 2010

Trop Anim Health Prod

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Data were collected over a period of 21 years (1988-2008) to estimate (co)variance components for birth weight (BWT), weaning weight (WWT), 6-month weight (6WT), 9-month weight (9WT), 12-month weight (12WT), average daily gain from birth to weaning (ADG1), weaning to 6WT (ADG2), and from 6WT to 12WT (ADG3) in Sirohi goats maintained at the Central Sheep and Wool Research Institute, Avikanagar, Rajasthan, India. Analyses were carried out by restricted maximum likelihood, fitting six animal models with various combinations of direct and maternal effects. The best model was chosen after testing the improvement of the log-likelihood values. Heritability estimates for BWT, WWT, 6WT, 9WT, 12WT, ADG1, ADG2, and ADG3 were 0.39 ± 0.05, 0.09 ± 0.03, 0.06 ± 0.02, 0.09 ± 0.03, 0.11 ± 0.03, 0.10 ± 0.3, 0.04 ± 0.02, and 0.01 ± 0.01, respectively. For BWT and ADG1, only direct effects were significant. Estimate of maternal permanent environmental effect were important for body weights from weaning to 12WT and also for ADG2 and ADG3. However, direct maternal effects were not significant throughout. Estimate of c (2) were 0.06 ± 0.02, 0.03 ± 0.02, 0.06 ± 0.02, 0.05 ± 0.02, 0.02 ± 0.02, and 0.02 ± 0.02 for 3WT, 6WT, 9WT, 12WT, ADG2, and ADG3, respectively. The estimated repeatabilities across years of ewe effects on kid body weights were 0.10, 0.08, 0.05, 0.08, and 0.08 at birth, weaning, 6, 9, and 12 months of age, respectively. Results suggest possibility of modest rate of genetic progress for body weight traits and ADG1 through selection, whereas only slow progress will be possible for post-weaning gain. Genetic and phenotypic correlations between body weight traits were high and positive. High genetic correlation between 6WT and 9WT suggests that selection of animals at 6 months can be carried out instead of present practice of selection at 9 months.

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Genetic parameter estimates for lamb growth traits and greasy fleece weight at first shearing in Turkish Merino sheep

Cited by 66 publications

References 21 publications

Genetic parameter estimates for growth traits in Iran-Black sheep

Genetic parameter estimates for growth traits in Iran-Black sheep

Estimates of (co)variance components and genetic parameters for growth traits of Avikalin sheep

Estimates of (co)variance components and genetic parameters for growth traits in Sirohi goat

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