Genomic analysis association of tolerance to heat stress in subtropical Egyptian goats Raised in hot dry environment

The study investigated subtropical Egyptian goat populations (382 does) from different hot dry ecological zones (Upper Egypt, Coastal Zone of Western Desert, and New Valley Desert Oasis) to identify genes associated with tolerance to heat stress. Animals were encouraged to walk for 7 km under direct solar radiation from 12:00 to 14:00 pm in July and August (imitating summer grazing on poor pasture under hot dry conditions). Temperature Humidity Index (THI) ranged from 98.6 to 109.3, indicating that the animals were under severe heat stress. Physiological parameters were measured at rest (7:00 am) and after exposure to heat stress (14.00 pm). Animal heat tolerant index (AHTI) was estimated from their response in the four main physiological parameters ranged from (0: high tolerant to 4: low tolerant). The GWAS analysis revealed 90 marker SNPs associated with heat stress in 108 genotypes of Egyptian goat. Ninety markers are found in forty-seven distinct genes distributed across the genome. In terms of the markers (SNPs) that have direct effect on these traits via homozygous alleles, twenty-eight SNPs are connected to heat stress. The snpeff approach revealed that KDM6A, TRPM3, USP54, GLTSCR2, NAALADL2, GATAD2A, CTNNA2, LOC102175876, ZBTB8A, ETNPPL, LRRC43, SNTB1, RPS6KA5, and ARHGAP26 genes influence tolerance to heat stress. These genes offer crucial insights into the biological mechanisms that enhance resilience to elevated temperature conditions. The studied subtropical Egyptian goat breeds showed a high ability to tolerate heat stress and identifying these genomic loci can be utilized to monitor and control tolerance of subtropical goat to heat stress, while maintaining their production performance.