Sow level risk factors for stillbirth of piglets in organic sow herds

Summary

In Danish organic pig production, one-third af total bom piglets die befare weaning, and stillbirth has previously crudely been estimated to account for 2 7% af the total preweaning mortality. The objective af this study was to evaluate season, litter size, parity and body condition af the sow as risk factors for stillbirth in nine commercial Danish organic pig herds. The study was conducted over a 1-year period, and the data included registrations an 5170 farrowings with 82 906 total bom piglets. The average number af total bom piglets per titter was 16. 0, and the number af stil/bom piglets per titter was 1.1. A significant effect af season was seen with an odds ratio for stillbirth af 1. 15 during summer (May to August) compared with the remaining part af the year. A non-linear effect af titter size was seen where an increase in litter size from 11 to 16 resulted in an odds ratio af stillbirth af 1.11. An increase in titter size from 16 to 21 resulted in an odds ratio af stillbirth af 1 .45. A significant interaction between body condition and parity was present. In first parity sows, an increase in body condition score from 2 (thin) to 3 (moderate) and from 3 to 4 (fat) increased the probability af stillbirth with an odds ratio af 1.23 and 1.36, respectively. In sows with parity above 4, an increase in body condition score from 2 to 3 and from 3 to 4 decreases the probability af stillbirth with an odds ratio af 0.68 and 0. 79, respectively. In conclusion, increasing litter size and being bom during the summer months af May to August were found to be risk factors for stillbirth. Furthermore, an interaction between body condition and parity showed that thin sows with parity above 4 had a substantially increased risk of stillbirth compared with normal and fat sows with parity above 4. In contrast, for parity 1 sows risk af stillbirth was increased in fat sows.