Back

Mostafa K. Nassar

Mostafa K. Nassar

Cairo University, Egypt

Title: Mapping Quantitative Trait Loci affecting polygenic traits in chicken

Biography

Mostafa K. Nassar is an Assistant Professor of Poultry Breeding, Genetics and Genomics at the Faculty of Agriculture, Cairo University, Egypt. He obtained PhD from Humboldt-Universitätzu Berlin, Germany in 2012 in the field of Breeding Biology and Molecular Genetics. He received MSc and B.Sc. from Cairo University, Egypt. Dr. Nassar is interested in discovering genes and their polymorphisms affecting polygenic traits as well as genetic diversity in chickens in order to improve breeding program efficiency. He also published several papers in peer-reviewed journals and in international conferences. Additionally, Dr. Nassar acts as a reviewer in Poultry Science Journal (PSA), US. He awarded several prizes, fellowships and grants.

Abstract

Growth traits are polygenic traits that are genetically determined by many genes. Knowledge of genes contributing to chicken growth can be used to identify polymorphisms of these genes in production lines to improve breeding program efficiency. A genome-wide scan was performed to detect chromosomal regions that affect 24 growth performance (body weight and body weight gain) and body composition (muscle mass, carcass parts and fat deposit) traits at different ages in reciprocal F2crosses (n = 579) between the inbred lines New Hampshire (NHI) and White Leghorn (WL77). The lines NHI and WL77 had been selected for high body weight at the age of 20 weeks and for low egg weight during laying period, respectively. Afterwards, the lines were inbred (Goraga et al. 2010). NHI chickens show a two-fold higher body weight at selection age compared to WL77.Linkage analyses provided evidence for highly significant quantitative traits loci (QTL) controlling growth performance and body composition on GGA2, 4 and 27. The peak QTL positions for different traits were located on GGA2 between 33.1 and 112.4 Mb, on GGA4 between 75.2 and 79.3 Mb, and on GGA27 between 3.6 and 3.8 Mb. The distal region of GGA4 (42.1 - 88.4 Mb) showed the highest effects on all analysed phenotypes. This region accounting for 4.6 to 40.2% of the phenotypic F2 variances of the corresponding affected traits (Nassar et al. 2012; 2013). Additional genome-wide significant and highly significant QTL for different analysed traits were mapped on GGA1, 5, 7, 10, 11, 12, 15, 26 and 27. For intramuscular fat content, a suggestive QTL was located on GGA14. Some loci have been reported in other studies. Other QTL effects were described for the first time. The majority of identified loci showed additive effects. The directions of the QTL effects were consistent in both reciprocal crosses, but the magnitude was higher in the high cross direction NHI x WL77. The difference between the parental lines and the highly significant QTL effects on GGA4 will further support fine mapping and candidate gene identification for growth traits in chicken.