7. Associations between Polymorphisms in the DIO3 Gene and Reproductive Traits and Carcass Performance in Pigs

Recently, DIO3 gene has been proposed as a candidate gene for litter size in pigs. Moreover, it was shown that polymorphism in this gene is associated with carcass traits. In this study we identified several SNPs within coding sequence of DIO3 by HRM method and performed association study between two polymorphisms and reproductive and carcass traits in pigs bred in Poland. Analysis of 350 pigs of Landrace and Large White breed revealed several significant associations for rs80999359, like period between the second and third parities (2IP)(P<0.0008) in the whole population, period between the third and fourth parities (3IP) (P<0.022), number of piglets born alive (L3NBA) (P<0.0084) and number of piglets at 21 days (L3NB21d) (P<0.0176) at the third parity in Large White as well as period between the second and third parities (2IP) (P<0.0012) in Landrace breed. The second polymorphism (rs80983654) was associated with 1IP (P<0.0218), number of piglets born alive at the fourth parity (L4NBA, P<0.027), number of piglets at 21 day at the fourth litter (L4NB21d, P<0.01), in the whole population, average number of piglets born alive (ANBA, P<0.01250), average number of piglets at 21 day (ANB21d, P<0.009), average interparity period (AIP, P<0.016), age at the first parity (1AP, P<0.003), (1IP, P<0.001, L4NBA, P<0.017, L4NB21d, P<0.005) in Large White breed. In contrast, we have found only few associations between DIO3 polymorphisms and carcass traits. rs80999359 was associated with backfat thickness (p<0.01) while rs80983654 with the weight of ham. Our results suggest that polymorphisms within DIO3 gene may be associated with reproductive traits.