Analysis of Stillbirth in Different Types of Sows

<正> Statistical analysis was conducted on sow stillbirth traits of three mating types with 1686 litters including Erhualian, Large White and F1. The number of stillborn piglets per litter (NSB) in Erhualian, Large White and F1 averaged 0.87, 0.32, 0.72, and the percentage born alive (PBA) averaged 95.1%, 97.1% , 95.7% , respectively. The Erhualian pig with a higher litter size also had a higher stillbirth rate. The results of the variance analysis indicated that the mating type, parity, farrowing year X farrowing season interaction and the total number born had highly significant effects on both NSB and PBA in sows (P < 0.001). Farrowing season had highly significant effects on NSB (P<0.01), and significant effects on PBA (P< 0.05). Farrowing year had no significant effects on NSB (P >0.05), and highly significant effects on PBA (P < 0.01). From parity 1 to parity 10, the least square means for NSB progressively increased with increasing parity, the least square means for PBA progressively decreased with in