الفهرس 
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Abstract
Poultry is one of the primary sources of cheap animal proteins in the form of meat and eggs. Great attention should be directed to meet the increased population demand through increased productivity and successful disease control, especially local breeds. Local breeds are characterized by high resistance to local environmental conditions due to their high vitality, high fertility rates, hatching, and their meat and eggs contain a low percentage of cholesterol, and they consume less food, and the Egyptian people prefer to eat meat and eggs over exotic chicken breeds. So, chicken has been selected for higher production performance over the years and is highly sensitive to changes in their environment. The average global temperature has increased over the century and is further expected to rise. In an open house rearing system, chicken is vulnerable to this increasing environmental temperature and may experience thermal stress. The chosen genotypes were in this study, El Fayoumi strain, as well as the Matrouh strain (to study the gene expression of the heat tolerance genes and the extent to which these strains tolerate heat stress) because El Fayoumi strain is considered one of the most critical pure local strains in Egypt, as its original origin is Upper Egypt, which is a dual-purpose breed to produce eggs and meat, while the Matrouh strain is a developed breed (from mating a white Leghorn male with a female Doki-4), and it is a dual-purpose breed to produce eggs and meat also.
HSPs are a highly conserved family of proteins playing an essential role in normal cellular physiology and cytoprotection against different stressors, including heat stress. In chicken levels, different HSP family members are increased in almost all the tissues in response to heat stress. This increased HSP level protects cellular proteins from heat stress-induced damage. They can function as molecular chaperones, facilitate protein folding, prevent protein aggregation, or target improperly folded proteins to degradative pathways.
Blood samples were collected from each strain to measure the gene expression related to the ability of the two Egyptian genotypes to withstand high temperatures using quantitative molecular genetics (qPCR) and gene sequencing. The following is a summary of the results.
RNA was extracted from frozen blood samples and converted into complementary DNA (cDNA); the qPCR using specific synthesized primers showed full induction of gene expression understudy in both genotypes but in different quantities. The current study demonstrated that El Fayoumi genotype is more tolerant to heat stress conditions through the high gene expression of the heat shock genes, while the Matrouh strain is the least tolerant of stress through a decrease in the gene expression of the heat shock genes.
The obtained results indicate that the native strains are more tolerant to heat stress conditions, as they showed the highest gene expression levels for both the hsp70 and hsf1 genes. Therefore, it is recommended to use the results of this study as a possible for transferring these genes (hsp70, hsf1) through appropriate crosses and transferring responsible genes for heat tolerance using genetic engineering technology.