Abstract

Barki is a sheep breed that is well-adapted to the harsh environmental conditions in Egypt without compromising its reproduction and productivity. Further, it remarkably contributes to the livelihood of many breeders, particularly in the desert regions of Egypt. This study investigated potential polymorphisms in the HSF1 and HSPA6 genes and their impacts on growth, adaptation traits, and blood parameters in 194 Barki lambs. Growth traits included birth weight, weaning weight (WW), and weights at 6 (W6) and 9 (W9) months of age. Adaptation traits included respiration rate, heart rate, body temperature, rectal temperature, and hormonal and biochemical blood profiles. The PCR-Restricted Fragment Length Polymorphism technique was applied to detect the allelic and genotypic frequencies of HSF1 and HSPA6 genes using SmaI and Cfr42I (SacII) restriction enzymes, respectively. The HSF1 exhibited two alleles (A and B) with only two genotypes, AB (0.46) and BB (0.52). However, the HSPA6 gene showed a monomorphic pattern. Association analysis revealed a significant effect of the HSF1 polymorphism on WW, W6, and W9. However, neither HSPA6 nor HSF1 polymorphisms significantly influenced adaptation traits or blood parameters. Lambs carrying AB genotypes had a relatively higher WW (16.14 kg) than BB lambs (13.7 kg). The fixed effect of lamb sex was significant on the weight at 9 months, with values of 34.43 kg for males and 28.17 kg for females. Male lambs were significantly heavier than females. Furthermore, lamb sex had a significant effect on respiratory rate (69.35 rpm for males and 60.48 for females), heart rate (87.48 rpm for males and 95.1 for females), urea (74 mg/dl for males and 41.21 mg/dl for females), aspartate aminotransferase (92.6 IU/L for males and 87.92 IU/L for females) and T3 hormone (2.75 ng/ml for males and 2.29 ng/ml for females). These findings elucidated that the HSF1 gene can be considered a functional candidate for improving growth performance in Barki lambs.