Title Genetic Analysis of HSP70 and HSF3 Polymorphisms and Their Association with Egg Production Traits of Bangladeshi Hilly Chickens

In hot environments, thermoregulation in poultry is regulated by heat shock protein 70 (HSP70), a member of HSPs, and its expression is controlled by the heat shock factor 3 (HSF3). Although the association between genetic polymorphism of these genes and thermotolerance as well as reproductive traits has been extensively studied in mammals but scarce in chickens. This study aimed to explore the relationship between single nucleotide polymorphisms (SNPs) in these genes and egg production traits of Bangladeshi Hilly chickens. To detect new SNPs and perform genotyping, sequencing and allele-specific PCR (AS-PCR) were used. We identified two novel SNPs(G-399A and A-68G) in the 5’-flanking regions of the HSP70 that were significantly associated with higher egg numbers(EN) at 161–190 days and increased egg weight(EW) at 40 weeks of age respectively. Furthermore, SNPs A258G, C276G, and C1431A in HSP70  and A-1388G in HSF3 also existed and were associated with EN at different ages. Haplotype and combined genotypic effects of these two genes were found to be associated with age at sexual maturity(ASM), body weight at ASM, EN, and EW. Identified SNPs and corresponding haplotypes might be useful in selective breeding to enhance the productivity of chickens in hot environments..