Expression levels of HSP70 and CPT-1 in three local breeds of chickens reared under normal or heat stress conditions after the introduction of the naked neck gene

Abstract The naked neck gene was introduced by crossbreeding into Egyptian breeds to improve body weight. Expression levels of HSP70 and CPT-1 were used to assess the heat tolerance of three Egyptian local breeds (Fayoumi, Dandarawi and Sinai) with and without the naked neck gene and under normal and heat stress conditions. There were two genotypes from each breed that had the same genetic origin (the naked neck and normal plumage genotypes). For each genotype, chicks were divided into two groups, a control group and a treated group. Chicks in the treated group were subjected to heat stress (40 °C) for four hours when they were between 3 and 5 days old. This treatment was associated with a highly significant increase in HSP70 and CPT-1 gene expression for the Dandarawi breed compared to the levels in the Fayoumi and Sinai breeds. Moreover, the introduction of the naked neck gene into these local breeds caused marked increases in CPT-1 gene expression, but these increases did not significantly differ among different naked neck genotypes. Therefore, it could be concluded that the Dandarawi breed exhibited the best heat tolerance, followed by the Sinai breed, whereas the Fayoumi breed was inferior in this respect. Furthermore, the naked neck gene improved heat tolerance by increasing HSP70 gene expression rather than only by reducing feather cover. The results obtained recommended using the Sinia naked neck chicken as a male line in commercial parent stock to produce broiler chicks adapted to the hot and warm climates.