Evaluation of Direct and Maternal ( CO ) Variance Components and Heritabilities for Some Body Weights and Growth Traits in Barki Sheep

El-Wakil, Salwa I.; Gad, S. M. A.

doi:10.12816/0005051

Cited by 4 publications

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“…In this study, the value of direct heritability of WW was 0.35, which is higher than the values of Aguirre et al [48] in the Santa Ines (0.20), Hammoud and Salem [49] in the Barki (0.012) and in Rahmani (0.139), Kumar et al [50] in Nellore (0.03), Mallick et al [51] in Bharat Merino lamb (0.16), Jawasreh et al [27] in Awassi (0.19), and Tariq et al [28] in Mengali sheep (0.125); it is similar to the results of Kariuki et al [52] in Dorper (0.28), Aksoy et al [29] in Karayaka (0.27), Hassen et al [30] in Awassi sheep in Ethiopia (0.33), Gamasaee et al [53] in Mehraban (0.30), El-Wakil and Gad [31] in Barki (0.30), and Hassen et al [30] in Nation (0.31); and it is lower than the values of El-Awady et al [54] in Rahmani (0.42) via Reml. In addition, the direct heritability of WW was estimated by Nassiri et al [55] in Zandi lambs (0.169), Barbosa et al [19] in Santa Ines (0.09), and Gowane et al [18] in Malpura (0.40) using Bayesian methodology.…”

Section: Resultssupporting

confidence: 77%

“…However, no important steps were taken in order to evaluate these records accurately to estimate parameters that would be the basis for ongoing selection programs. In the literature, there are many studies using the REML method to estimate genetic parameters of different breeds [27][28][29][30][31][32]. However, some researchers used different animal models under the Bayesian approach in small ruminant animals [18,19].…”

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confidence: 99%

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Estimation of genetic parameters for weaning weight of Awassi lambs by using classical and Bayesian methods

Tatliyer¹,

Baş²

2020

Turk J Vet Anim Sci

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IntroductionVariance sources are the basis for organization of progeny testing, calculation of genetic-environment interaction, construction of selection index, calculation of mixed model BLUP, estimation of phenotype-environment correlation, planning of improvement program with identified genetic structure in quantitative characters, estimation of variance components, and estimation of accurate breeding value [1,2]. Accuracy of estimation of variance components depends on factors that include observations, statistical model used, and method [3]. Therefore, many researchers have tried to improve different methods for estimation of variance components [4][5][6][7][8][9]. ANOVA, ML, and REML are the most used methods for estimation of genetic variance [10]. These methods have been called classical approaches (frequentist, Berkeley methods) and are based on normality assumption. However, the existence of threshold traits and the observation of binary data in animal breeding violates the rule of normality assumption [11,12]. Therefore, the Bayesian approach, another alternative method to overcome this concern, has been developed and this approach that does not require normality can be alternatively used to estimate variance components by using posterior distribution in discrete and continuous distributed traits [13][14][15][16]. In this respect, the Bayesian approach has more advantages than the classical approach in practice [17]. At the same time, no negative variance can be estimated under the Bayesian approach [18]. In the genetic evaluation of animals, the use of the MCMC algorithm in Bayesian approach has been a good option and this approach has been reducing bias in the estimations even when the dataset is too small [19]. At the same time, the Bayesian approach is statistically more flexible for estimations of variance components than the REML procedure [15]. In addition, some researchers have suggested that the use of the MCMC algorithm in the Bayesian approach is more feasible although it is computationally more expensive [20,21]. However, with the developed computer technology, various programs such as MTGSAM [22], GIBANAL [23], MCMCglmm [24], and FlexQTLs [25,26] have increased the popularity of the Bayesian approach. Under the National Small

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Section: Resultssupporting

confidence: 77%

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confidence: 99%

Estimation of genetic parameters for weaning weight of Awassi lambs by using classical and Bayesian methods

Tatliyer¹,

Baş²

2020

Turk J Vet Anim Sci

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“…Maternal correlation coefficients (either genetic or environmental) among the studied body weights (BW, WW and YW) appeared to be positive and higher than the corresponding phenotypic and direct ones (either genetic or environmental) as seen from Table (2). These results probably emphasize the importance of maternal effects to control the studied body weights and growth traits in Barki sheep as reported earlier by El-Wakil and Gad (2014). It seems that body weight from birth to the yearling stage is largely influenced by similar genes of the dam in terms of maternal genetic effects.…”

Section: Correlation Coefficientssupporting

confidence: 83%

“…That breeding program has been evaluated recently from the perspectives of genetic, phenotypic and environmental trends for some body weights (El-Wakil and Elsayed, 2013). The idea of the present study came to the interest since the importance of maternal effects on body weights of Barki sheep has been emphasized recently (El-Wakil and Gad, 2014) and the implications of maternal influences on the genetic improvement program has not been fully investigated in Barki sheep. It would be of interest to study direct and maternal genetic correlations among the studied traits and asses such implemented breeding program by investigating direct and Egyptian J. Anim.…”

Section: Introductionmentioning

confidence: 99%

Direct and Maternal Genetic Parameters and Genetic Trends for Some Body Weights and Growth Traits in Barki Sheep

El-Wakil

Gad

2014

Egyptian Journal of Animal Production

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Body weight records of 3189 Barki lambs progenies of 186 sires and 1748 ewes were obtained from Barki sheep flock maintained at Ras Elhekma (from 1963 to 1972) and Maryout (from 1973Maryout (from to 2004 research stations which belong to the Desert Research Centre in order to assess direct and maternal genetic parameters and genetic trends to evaluate the breeding strategies implemented for improving growth performance in Barki sheep. The present study dealt with body weights at birth, BW; weaning, WW and yearling, YW as well as average daily gain from birth to weaning, DGBW and from weaning to yearling, DGWY. Data were analyzed by fitting a direct-maternal animal model using the MTDFREML program to estimate direct and maternal expected breeding values and correlations. Breeding values were plotted against year of birth to obtain genetic trends for the studied traits.Results indicated the importance of maternal effects on the studied body weights and growth traits in Barki sheep. Maternal correlation coefficients (either genetic or environmental) were positive and higher than the corresponding phenotypic and direct ones. Genetic trend analysis for the studied traits indicated, on one hand, that there is virtually no difference between direct and maternal breeding values and hence genetic trends across the examined years which reveal that maternal genetic effects are of importance and probably have the same impact as the direct genetic effects. On the other hand, two distinct trends were clearly illustrated in which the positive genetic trends in body weight exhibited till 1975-1976 and then dropped and remained constant, thereafter. This time probably coordinated when the sheep flock had just moved from Ras Elhekma to Maryout research station. At Ras Elhekma research station, genetic progress achieved in the studied traits appeared to be generally significant and positive but of little magnitude throughout the examined years with slightly higher maternal genetic improvement compared with the respective direct genetic one. However, the annual direct and maternal genetic trends were generally negative, not significant and almost zeros at Maryout research station. Such no or minor genetic response exhibited for the studied traits during the evaluated years might be a result of lacking effective directional selection, management system applied and incompatible environmental conditions. Likewise, it could probably be attributed to neglecting the maternal influences either genetic or environmental throughout the implementation of breeding program which used to depend entirely on direct genetic effects. Implications of including both direct and maternal effects into the breeding program to improve growth performance in Barki sheep have been discussed.

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“…They are fat-tailed and while it is a dual-purpose sheep (meat and wool), they are mostly kept for their mutton production. For faster genetic improvement and increasing the efficiency of the prevailing production system, accurate genetic parameters for economically important traits are prerequisite in order to obtain reliable estimates to enhance the accuracy of selection for breeding animals (El-Wakil and Gad, 2014). Meat yield is a complex polygenic trait that is highly affected by non-genetic and genetic factors.…”

Section: Introductionmentioning

confidence: 99%

Estimation of Genetic Parameters for Body Measurements and Their Relationship With Body Weight in Barki Lambs

Gad

2014

Journal of Animal and Poultry Production

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The aim of the present study was to investigate the importance of direct and maternal effects on the body measurements and live weight of Barki lambs. Data of 214 lambs progenies from 36 sires and 98 dams recorded of Barki of Sheep flock in Maryout Research Station at Desert Research Center was used to estimate the genetic parameters of body measurements and yearling live weight in Barki lambs. The used traits in present study were: body length (BL), height at withers (HW), heart girth (HG) and yearling weight (YW). The estimations were done by using DFREML software. Direct heritability by single trait analysis was estimated 0.10, for BL, 0.18, for HW, 0.10, for HG, and 0.10, for YW. The effect of permanent environmental due to dam was estimated 0.05, 0.02, 0.06 and 0.04 for BL, HW, HG and YW, respectively. Using bivariate analysis, additive genetic correlations were estimated 0.75, 0.76 and 0.93 between YW and each of BL, HW and HG, respectively. High and positive genetic and phenotypic correlations indicate that an improvement in body measurements both at the genetic and phenotypic level is expected through selection on body weight and vice versa. keywords: Barki lambs,direct heritability, permanent environmental and genetic correlation.

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Evaluation of Direct and Maternal ( CO ) Variance Components and Heritabilities for Some Body Weights and Growth Traits in Barki Sheep

Cited by 4 publications

References 0 publications

Estimation of genetic parameters for weaning weight of Awassi lambs by using classical and Bayesian methods

Estimation of genetic parameters for weaning weight of Awassi lambs by using classical and Bayesian methods

Direct and Maternal Genetic Parameters and Genetic Trends for Some Body Weights and Growth Traits in Barki Sheep

Estimation of Genetic Parameters for Body Measurements and Their Relationship With Body Weight in Barki Lambs

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