Direct and maternal (co) variance components and heritability estimates for body weight at different ages and fleece traits in Afrino sheep

Snyman, M.A.; Erasmus, G.J.; Wyk, J.B. van; Olivier, J.J.

doi:10.1016/0301-6226(95)00071-2

Cited by 120 publications

(116 citation statements)

References 12 publications

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“…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 permanent environmental maternal effect (c 2 ) for birth weight (0.09) in our study was in agreement with the findings of Maria et al (1993) and Mandal et al (2006) in other sheep breeds. However, the estimates reported by Tosh and Kemp (1994) in Hampshire, Polled Dorset, and Romanov sheep; Snyman et al (1995) in Afrino sheep; Neser et al (2001) in Dorper sheep; and Ekiz et al (2004) in Turkish Merino lambs were higher as compared to the present findings. The permanent environmental effect (c 2 ) due to the dam can be ascribed to uterine environmental effects and the feeding level in late gestation of the ewe (Maria et al 1993;Snyman et al 1995).…”

Section: Birth Weightcontrasting

confidence: 81%

“…However, the estimates reported by Tosh and Kemp (1994) in Hampshire, Polled Dorset, and Romanov sheep; Snyman et al (1995) in Afrino sheep; Neser et al (2001) in Dorper sheep; and Ekiz et al (2004) in Turkish Merino lambs were higher as compared to the present findings. The permanent environmental effect (c 2 ) due to the dam can be ascribed to uterine environmental effects and the feeding level in late gestation of the ewe (Maria et al 1993;Snyman et al 1995). The high maternal effect at birth indicates that the maternal effect would have a considerable effect on selection response for this trait.…”

Section: Birth Weightcontrasting

confidence: 81%

“…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 Weightcontrasting

confidence: 78%

“…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). Hence, to achieve optimum progress in a selection program, both direct and maternal components should be taken into account, especially if there is an antagonistic relationship between them.…”

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 Weightsupporting

confidence: 89%

Section: Birth Weightcontrasting

confidence: 81%

Section: Birth Weightcontrasting

confidence: 81%

Section: Weaning Weightcontrasting

confidence: 78%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

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 direct and maternal (co)variance components as well as genetic parameters of growth traits in Nellore sheep

Kumar

Gangaraju

et al. 2017

Trop Anim Health Prod

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In the present study, (co)variance components and genetic parameters in Nellore sheep were obtained by restricted maximum likelihood (REML) method using six different animal models with various combinations of direct and maternal genetic effects for birth weight (BW), weaning weight (WW), 6-month weight (6MW), 9-month weight (9MW) and 12-month weight (YW). Evaluated records of 2075 lambs descended from 69 sires and 478 dams over a period of 8 years (2007-2014) were collected from the Livestock Research Station, Palamaner, India. Lambing year, sex of lamb, season of lambing and parity of dam were the fixed effects in the model, and ewe weight was used as a covariate. Best model for each trait was determined by log-likelihood ratio test. Direct heritability for BW, WW, 6MW, 9MW and YW were 0.08, 0.03, 0.12, 0.16 and 0.10, respectively, and their corresponding maternal heritabilities were 0.07, 0.10, 0.09, 0.08 and 0.11. The proportions of maternal permanent environment variance to phenotypic variance (Pe) were 0.07, 0.10, 0.07, 0.06 and 0.10 for BW, WW, 6MW, 9MW and YW, respectively. The estimates of direct genetic correlations among the growth traits were positive and ranged from 0.44(BW-WW) to 0.96(YW-9MW), and the estimates of phenotypic and environmental correlations were found to be lower than those of genetic correlations. Exclusion of maternal effects in the model resulted in biased estimates of genetic parameters in Nellore sheep. Hence, to implement optimum breeding strategies for improvement of traits in Nellore sheep, maternal effects should be considered.

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Direct and maternal variance components and genetic parameters for average daily body weight gain and Kleiber ratios in Nellore sheep

Illa

Gollamoori

Nath

2018

Trop Anim Health Prod

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The objective of the present study was to estimate variance components and genetic parameters for average daily gain from birth to weaning (ADGa), birth to 6 months (ADGb) and 3 to 6 months (ADGc) and corresponding Kleiber ratios (Ka, Kb, and Kc) in Nellore sheep. Data were collected from the records maintained at Livestock Research Station, Palamaner, for analysis and the data spread from 1993 to 2016 (23 years). Lambing year, sex of lamb, season of lambing, and parity of dam were included in the model as fixed effects, and ewe weight was kept as a covariate. Six animal models were fitted with various combinations of direct and maternal genetic effects using restricted maximum likelihood procedure. The Akaike's information criterion was employed to determine the best model for each trait. Direct heritability estimates obtained in the study for ADGa, ADGb, ADGc, Ka, Kb, and Kc were 0.37, 0.41, 0.34, 0.48, 0.46, and 0.37, respectively, and their corresponding maternal heritabilities ranged from 0.11, 0.21, 0.11, 0.24, 0.22, and 0.11, respectively. (Co)variance among the direct and maternal effects were found to be negative in all the traits. Direct genetic correlations among the studied traits were positive with few exceptions, and they ranged from - 0.03 (Ka-Kc) to 0.99 (ADGa-Ka); similarly, the phenotypic correlations ranged from low to high - 0.18 (ADGa-Kc and Ka-Kc) to 0.95 (ADGa-Ka). These results indicated the importance of maternal effects in affecting the growth rate and efficiency of feed utilization traits and also suggested the possibility of moderate genetic progress for these traits through selection.

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Direct and maternal (co) variance components and heritability estimates for body weight at different ages and fleece traits in Afrino sheep

Cited by 120 publications

References 12 publications

Genetic parameter estimates for growth traits in Iran-Black sheep

Genetic parameter estimates for growth traits in Iran-Black sheep

Estimates of direct and maternal (co)variance components as well as genetic parameters of growth traits in Nellore sheep

Direct and maternal variance components and genetic parameters for average daily body weight gain and Kleiber ratios in Nellore sheep

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