INTEGRATION OF QTL DETECTION OF GROWTH TRAITS AND ASSOCIATION STUDY FOR CHICKEN CHROMOSOME 4 | ||||
| Egyptian Poultry Science Journal | ||||
| Article 12, Volume 40, Issue 1, January 2020, Page 191-207 PDF (1.12 MB) | ||||
| Document Type: Original Article | ||||
| DOI: 10.21608/epsj.2020.78762 | ||||
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| Author | ||||
Tarik S.K.M Rabie
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| Animal Production and Fish Resources Dept., Faculty of Agriculture, Suez Canal University | ||||
| Abstract | ||||
| Quantitative trait locus (QTL) mapping opens a way for breeders to manipulate quantitative trait genes. The objective of this study is to detect the QTL related to growth performance in local breeds of chicken. A cross between three genetically different chicken’ breeds was used to produce two generations populations. Total of 16 Saso cocks, and 32 hens (16 of each of Alexandia and Fayoumi) as parents were used to produce first generation (G1). Data of 954 chicks produced during the auxiliary two generations of different crosses (S♂xF♀, S♂xA♀, SF♂xSF♀, SA♂xSA♀, SF♂xSA♀ and SA♂xSF♀) in such a way the genetic homogeneity from G0 to G2 recombinant populations has been considered. These populations were used for detection and localization of QTL related to the growth traits; body weight (BW), growth rate (GR), and average daily gain (ADG). A number of 25 microsatellite markers belong to chicken chromosome 4 (GGA4) have been genotyped, and the regression interval mapping approach was used to identify QTL. The results revealed that all selected markers were informative. There was a statistical evidence for QTL on GGA4 for BW at 8 and 12 weeks of age, whereas one QTL exceeded the significant threshold for the trait of BW at 8 weeks of age. The related trait, growth rate, reached the suggestive threshold. All of three QTL effects identified on GGA4 had their maximum test statistic in the region between 134-154 cM. In addition, most of significant markers (MCW0390, MCW0393, MCW0397, MCW0409, MCW410 and UMA0038) were associated with growth traits at all chicken ages. Although, the polymorphism information content (PIC) obtained over all microsatellite markers was 46%, that around 82% went to UMA0038 locus. Two private alleles were found for markers MCW0405 and MCW0409 with allele frequency around 0.025 in G1 and G2 respectively. Additionally, Chi-square test was used to investigate the deviation of loci from Hardy-Weinberg equilibrium individually, and four microsatellite markers (MCW0395, ADL0266, MCW0400 and UMA0038) were not in genetic equilibrium. In addition, analysis of molecular variance (AMOVA) revealed that 14% and 86% of variance were observed among and within individuals, respectively. The obtained small value of FST (ranged between 0.001 to 0.019) may reflect generous genetic differentiation. In conclusion, the recognized QTL, integrated with the association study, gave useful and practical information to distinguish molecular genetic factors that influence growth traits within the local populations of chicken. | ||||
| Keywords | ||||
| Poultry; QTL; Microsatellite markers; Crossing; Growth; GGA4 | ||||
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