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This study aims to elucidate the effects of single nucleotide polymorphisms (SNPs) in the 5′-flanking region of porcine heat shock protein 70.2 gene (HSP70.2) on semen quality in boars. Genomic DNA isolated from 55 boars (41 Duroc, nine Landrace, and five Yorkshire) was subjected to PCR amplification of the 5′-flanking region of HSP70.2. The nucleotide sequences were determined by automated sequencing. Five SNPs (sites 44, 232, 250, 345, and 393) were detected in this region. Semen quality was evaluated in terms of sperm motility, percentage of normal sperm, percentage of sperm with proximal plasma droplet, percentage of abnormal sperm, sperm concentration, semen volume per ejaculate and total sperm number per ejaculate. The effect of the SNPs on semen quality was evaluated based on breed-corrected data within a season. During the cool season, the sperm motility of boars with AA genotype at the 232 site was significantly higher than that of boars with CC genotype (P<0.05). Meanwhile, boars with AC genotype at the 232 site had higher total sperm number per ejaculate than did those with CC genotype. In the hot season, heterozygotes at both the 232 and 250 sites had significantly higher total sperm number of per ejaculate than AA homozygotes (P<0.05). Semen volume of boars with TT and TC genotypes at the 345 site was significantly larger than that of those with CC genotype (P<0.05). Meanwhile, semen quality for boars with TT genotype at the 345 site was significantly higher than that of boars with TC or CC genotype (P<0.05), that is the semen contained higher percentages of normal sperm and lower percentages of abnormal sperm or sperm with proximal plasma droplets. Results herein suggest that the SNPs in the 5′-flanking region of porcine HSP70.2 are associated with semen quality traits in the hot season. [Copyright &y& Elsevier]

The 5′-flanking region in heat-shock protein 70.2 gene (HSP70.2) has been found to be associated with meat quality, birthweight, and semen quality in pigs. This study examines the relation between the genotype of five polymorphic sites in the 5′-flanking region of porcine HSP70.2 with backfat thickness and growth performance under different environmental conditions, especially the cool (low temperature 12–19 °C, high temperature 19–25 °C) and hot (low temperature 21–25 °C, high temperature 28–33 °C) seasons. A total of 216 Duroc boars were performance tested in both seasons using segregated early weaning entrance. Haplotypes of the 5′-flanking region of the animals were determined using the single nucleotide polymorphisms of their siblings and/or parents. Additionally, six haplotypes were found in the tested samples and used to construct 15 genotypes. The animals with the most prevalent nine genotypes were further analyzed to determine the interaction between genotype and season. Genotype significantly influenced backfat thickness (P<0.001). Furthermore, the interaction of genotype and season was found to influence both backfat thickness (P<0.01) and feed efficiency (P<0.05). Most of the variation in backfat thickness and feed efficiency was caused by pigs of certain genotypes raised during the cool season. Taken together, we suggest that variation of backfat deposition under different weather conditions may occur in Duroc boars with different genotypes of the 5′-flanking region of HSP70.2. [Copyright &y& Elsevier]