Abstract: Reproductive performance of stock sows is one of the important factors of economic impactin pig farms. In this study, 8491 litter records from 2699 sows of Yorkshire, Landrace, and Duroc were analyzed usingfixed model to determine the effect of parity, mating season, and breed on total number born (TNB), number healthy birth (NHB), litter birth weight (LWB), number weak birth (NWB), stillbirth, mummy fetus, and deform fetus by the least square analysis. Genetic parameters of the above traits were estimated by restricted maximum likelihood (REML) procedure. In addition, the effectiveness of pure-breeding and cross-breeding on litter performance were compared. The results showed that, parity, mating season, and breed had significant effect on TNB, NHB, and LWB(P < 0.001).The effects of parity and breed were significant on NWB(P <0.001), while mating season had non-significant effect on NWB. Parity showed significant effect on still-birth, while the effect of mating season and breed was not significant. Parity, mating season, and breed had no significant effect on mummy fetus and deform fetus. Landrace♂×Large White♀ showed the best litter performance, including TNB, NHB, and LWB. Moreover, LWB of Landrace depicted the highest heritability, while other traits were all bellow 0.2. The genetic correlation between TNB and NHB, NHB and LWB were higher than 0.96 in the three breeds. These results pro-vided reference data for minimizing low-reproductive performance caused by non-infectious factors and improving sow reproductive performance in pig farms.

Key words: stock sow, reproductive traits, influence factors, genetic parameters