Genetic Analysis of HSP70 and HSF3 Polymorphisms and Their Associations with the Egg Production Traits of Bangladeshi Hilly Chickens.

Simple Summary: Heat stress is a challenging environmental factor that affects poultry production. Adaptation to heat stress is regulated by heat shock proteins (HSPs). In chickens, HSP70 expression is controlled by heat shock factor 3 (HSF3). The genetic diversity of heat shock genes is thought to be closely associated with the productive and reproductive performance of farm animals. The present study aimed to explore the relationships between single-nucleotide polymorphisms (SNPs) in the genes of Bangladeshi hilly chickens and their egg production traits. Sequencing and allele-specific PCR identified two novel SNPs (G-399A and A-68G) in the 5′-flanking regions of HSP70. In addition, three previously identified SNPs in HSP70 (A258G, C276G and C1431A) and two SNPs in HSF3 (A-1388G and A-1703G) were also genotyped. A population of 150 breeding hilly chickens was used to analyze the associations between SNPs in these genes and the chickens' egg production traits. Among the analyzed SNPs, the two novel SNPs (G-399A and A-68G) were significantly associated with egg number and egg weight, respectively. In addition, all other SNPs except A-1703G were also found to be associated with egg production traits. These results suggest that the identified SNPs in these genes might be useful in a selective breeding program to enhance productivity in warm environments. In warm environments, thermoregulation in poultry is controlled by heat shock protein 70 (HSP70), whose expression is controlled by heat shock factor 3 (HSF3). Although the association between genetic polymorphisms in these genes and thermotolerance as well as reproductive traits has been extensively studied in mammals, the association has not yet been studied in poultry. This study aimed to explore the relationship between single-nucleotide polymorphisms (SNPs) in these genes and the egg production traits of Bangladeshi hilly chickens. Sequencing and allele-specific PCR (AS-PCR) were used to detect new SNPs and perform genotyping. We identified two novel SNPs (G-399A and A-68G) in the 5′-flanking regions of HSP70 that were significantly associated with egg numbers (ENs) at 161–190 days and increased egg weight (EW) at 40 weeks of age. Furthermore, three SNPs in HSP70 (A258G, C276G and C1431A) and one SNP in HSF3 (A-1388G) were associated with EN at different ages. The haplotype and combined genotypic effects of these two genes were found to be associated with age at sexual maturity (ASM), EN, EW, and body weight at ASM. The identified SNPs and their corresponding haplotypes may be useful in selective breeding to enhance the productivity of chickens in warm environments. [ABSTRACT FROM AUTHOR]