Association of the estrogen receptor 1 and 2 polymorphisms with fat distribution in heavy pigs

More than 80% of Italy's pig production is used in the production of traditional dry cured ham. Dry cured ham production requires fresh legs with at least 15 mm of fat coverage. For decades, Italian pigs have been selected for fatness, as legs constitute almost 60% of the commercial value of the animal. Lately, however, thigh prices have dropped, increasing the economic importance of the Longissimus dorsi (L. dorsi) to the pig industry. This research sought to identify genes that can modulate fat repartitioning, resulting in fat legs and lean L. dorsi. As estrogens are known to control the distribution of body fat in humans and rodents, we investigated the polymorphisms in the estrogen receptor 1 (ESR^{PvuII5700/4200}) and estrogen receptor 2 (ESR2 A949G) genes in 612 pigs (278 females, 334 castrated males) and collected the following phenotypical data: carcass weight, lean percentage, leg weight, back fat and leg fat thickness. Castrated males of the ESR^{PvuII5700/5700} genotype had significantly more back fat (P < 0.05) with no significant effect on leg fat. Conversely, ESR^{PvuII5700/5700} females had significantly less leg fat (P < 0.05) with no significant effect on back fat. Both males and females of the ESR2 A949A genotype had less leg fat (P < 0.05) without any effect of the polymorphism on back fat. Our findings suggest that ESR^{PvuII5700/4200} and ESR2 A949G polymorphisms are associated with subcutaneous fat localization in pigs.