Abstract
Background:
Heat stress is a major constraint in the production of tropical cattle, reducing performance and reproductive efficiency through cellular thermal and oxidative challenges. Heat shock proteins, including HSPB1 (HSP27) and HSP70, play central cytoprotective roles; however, information on genetic polymorphisms and haplotype diversity of these genes in indigenous Indonesian cattle, particularly Pesisir cattle, remains limited.

Aim:
This study aimed to characterize the sequence polymorphisms and haplotype diversity of the HSP27 (HSPB1) and HSP70 genes in Pesisir cattle.

Methods:
Blood samples were collected from 95 Pesisir cattle in Pesisir Selatan Regency, West Sumatra, Indonesia. Genomic DNA was extracted and PCR-amplified for HSP27 (1415 bp) and HSP70 (963 bp) fragments, followed by one-directional Sanger sequencing. Sequence alignment was performed to identify SNPs and insertions/deletions (indels). Genotype and allele frequencies, heterozygosity, HWE, and haplotype patterns were analyzed.

Results:
A total of 31 nucleotide variants were identified across both genes, comprising 20 in HSP27 and 11 in HSP70. HSP27 variants included 15 in intron 1 and 5 in exon 2, whereas HSP70 variants were detected within the coding region. Population-genetic analyses were conducted for 15 and 8 SNP loci in HSP27 and 8 SNP loci in HSP70. Heterozygosity indicated low-to-moderate genetic variation, and HWE departures were observed at multiple loci (HSP27: 11/15; HSP70: 6/8). Putative haplotype patterns were identified for both genes, indicating within-breed sequence diversity.

Conclusion:
HSP27 (HSPB1) and HSP70 genes in Pesisir cattle exhibit measurable polymorphism and haplotype variation. These baseline genetic data provide a foundation for future validation and genotype–phenotype studies related to thermotolerance, as well as for the development of conservation and genetic improvement strategies for Pesisir cattle.

Key words: Heat stress adaptation; HSPB1 (HSP27); HSP70; Genetic polymorphism; Pesisir cattle.