International Journal of Modern Biology and Medicine
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Table of Content for Vol. 10 No. 1, 2019

Direct and Maternal Genetic Trend Estimates for Growth Traits of Zaraibi Goats in Egypt Using Multivariate Animal Models
El-Awady, H. G., M.M. El-Moghazy, I.A.M. Abu El-Naser, and A.A. El-Raghi
      
 PP. 1 - 19
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ABSTRACT: The aim of the present study was to estimate direct and maternal genetic trends for growth traits of Zaraibi goats in Egypt by using data of 2998, 2752, 2713, 2604, 2507 and 2009 kids of 763 does mated with 75 bucks for body weight at birth (BW), 30 day (W30), 60 day (W60), weaning (WW), 120 day (W120) and 180 day (W180), respectively. Data were collected through the period from 2005 to 2012 from Zaraibi herd raised in El-Serw Experimental Station, located in the North Eastern part of the Nile Delta, belongs to Animal Production Research Institute (APRI), Ministry of Agriculture, Egypt. Variance and covariance components analyzed by Derivative-free restricted maximum likelihood (REML) using animal model. A multivariate animal model analysis was applied to predict the breeding values of individual for the studied traits. For each trait, genetic trends were obtained by regression the means of predicted breeding values on year of birth. Direct heritability estimates ranged from 0.23 to 0.43, 0.28 to 0.41, 0.20 to 0.31, 0.17 to 0.34, 0.15 to 0.32 and 0.24 to 0.28 for BW, W30, W60, WW, W120 and W180, respectively. Corresponding maternal heritability for mentioned traits tends to decline from BW (0.21) to W180 (0.07), indicating that maternal effects on BW, W30 and W60 of Zaraibi goats need to be considered in any selection program. The correlations between direct and maternal genetic effects (ram) were positive for W30 (0.34), W60 (0.42) and WW (0.37), while the negative signs were observed for BW (-0.19), W120 (-0.47) and W180 (-0.42). Estimates of the fraction of variance due to maternal permanent environmental effects decreased from 0.12 for BW to 0.05 for W180, indicating the adaptation of animal to environmental conditions in older ages. Direct and maternal genetic correlations among kids weights ranged from 0.40 (BW-W180) to 0.85 (W60-WW) and from 0.47 (BW-W180) to 0.90 (WW-W120), respectively. Meanwhile, phenotypic correlations ranged from 0.35 (BW-W180) to 0.96 (WW-W120). Annual direct genetic trends for BW, W30, W60, WW, W120 and W180 were 6.22, 16.64, 7.731, 33.501, 31.986 and 72.419 g/year, respectively. Corresponding maternal genetic trends were -5.200, 22.51, 15.215, 24.59, -24.05 and -23.805 g/year, respectively. Phenotypic trends for growth traits by year of calving were 3.05, 39.74, 27.75, 55.99, 8.24 and 59.82 g/year, while the maternal permanent environmental trends were 0.024, 0.1012, 0.1149, 0.1435, 0.2261 and 0.1464 g/year for mentioned traits respectively.