استخدام المعلمات الوراثية فى التوصيف الوراثى والحفاظ على بعض السلالات والخطوط المحلية للدجاج المصرى

INTRODUCTION:

Chickens provide an important source of human food around the globe through their egg and meat production. In 2005, the world’s total chicken meat production was 266 million tons (about 27% of the world’s total meat production), and the world’s total egg production was about 65 million tons (http://faostat.fao.org/). The chicken also serves as a model organism for studies in biology and agriculture (Siegel et al. 2006). As a result of many years of domestication and breeding, a wide range of chicken breeds exist today. However, an increasing number of local chicken breeds are under threat of extinction, and valuable genotypes and traits are at risk of being lost (Blackburn 2006). Based on analysis done in DNA pools of a wide range of populations, genetic diversity among chicken breeds seems to be lower than in other domesticated species (Hillel et al. 2003). Loss of genetic diversity in the chicken gene pool may be the result of intensive selection in breeding programs.

To conserve genetic diversity in this species, a comprehensive characterization of chicken breeds collected from around the world is required. The extent of genetic diversity depends on the genetic founders of the populations as well as the management that these populations have undergone. The characterization of indigenous animal genetic resources is a requisite step in providing needed information for the conservation of useful genotypes against future needs (Osei-Amponsah et al. 2010).

In developing countries selection pressure for production traits is low and traditional chicken breeds are used in rural animal production systems. It is especially favorable to the smallholder systems of the developing countries of the tropics due to low capital investments, high cost efficiency and low production risk. Though the importance of local chicken populations in human supply, information on their genetic description with respect to performance, adaptability, resistance, genetic variability and genetic relationships is scarce. This is mostly recognized as the loss of rare breeds especially in developed countries. This led to the sense that the identification of important genetic resources and the prevention of further loss of genetic variation is an important task. Therefore the evaluation of exotic local breeds as genetic resources is of interest in efforts to maintain genetic variation. An important contribution to the identification of genetic resources is the estimation of genetic variation within and between populations.

We expect that over the coming years we will see a growing number of major genes being directly selected for in poultry breeding programs. Taken together, we predict that within ten years from now selection procedures based on genomic information will be an essential part of every poultry breeding program. We believe that such selection procedures could well turn into the core of the breeding program. After all, the genome is the core of genetic variability, the livelihood of breeding companies. Thus, molecular breeding technology contains all aspects of what is called a breakthrough development.

So the current research project aimed to open a new horizon in Egypt using gene banking and molecular genetics as new techniques in gene pool preservation and to study genetic description and variation in some local breeds and strains of chicken.

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