Association of Hsp70 locus polymorphism with thermotolerance and ailment occurrence in Gulf Creole cattle within intensive systems

Objective: To estimate thermotolerance by analyzing physiological constants and ailment occurrence in Gulf Creole bovine cattle (GCB) and to relate them to Hsp70 locus polymorphism under an intensive production system. Design/Methodology/Approach: Using a 440 bp fragment, we genotyped leukocyte DNA from 60 BCG through PCR-RFLP (Fok I). Physiological variables were estimated at 7-day intervals for four months during the hottest season. The variables considered were respiratory rate (RR) and layer temperature (LT). Environmental variables—temperature and humidity— were also recorded to determine thermal comfort. Using the production system database, we categorized the animals’ ailments during the studied period. Results: The Hsp70 gene in GCB is polymorphic. The frequency of the AB heterozygous genotype was 0.77; for the AA homozygous genotype, it was 0.23. We observed a predominance of the A allele (0.61). Data analysis allowed us to find differences in RR in GCB with AA and AB genotypes (p<0.05). LT showed no differences (p>0.05). The genotype did not affect ailment occurrence in GCB (p>0.05). Study limitations/implications: Since the intensive system is dynamic, and the GCB stay period is short, few animals were available for the study. Findings/Conclusions: The Hsp70 gene present in GCB is polymorphic, and the animals are thermotolerant. Their performance regarding the occurrence of clinical conditions is favorable.