High mortality in the pig industry is a welfare problem and it reduces the farmer’s income. The Danish Pig farmers have decided to reduce the mortality with 20% before 2020 compared to the 2011 level. For each percent the mortality is reduced in the farrowing units the gross margin per sow per year is increased by 6 euro. The objective of this study was to assess the impact of cross fostering and later movements of piglets on preweaning mortality.
The hypothesis was that cross fostering, later movements, and birth weight of pigs are associated with preweaning mortality. The study was performed as a cohort study in 9 farrow-to-finish herds with more than 1.8 stillborn piglets per litter. Approximately 70 consecutive farrowings in each herd were included in the study. For sows their ID, parity, farrowing data, and treatments were recorded. Each piglet was weighed and ear tagged at birth. All pig treatments, cross fostering and later movements were recorded. Cross fostering was movements of pigs on the day of birth. Movements from day 2 were analyzed separately. Cross fostering and movements from day 2 were analyzed as time dependent variables. Only the first cross fostering on the day of birth and the first movement from day 2 was included in the analysis. Additional cross fostering or additional movements from day 2 were not included in the analysis. Birth weight was included as a covariate.
A total of 8611 live born piglets were included in the statistical analysis and 1615 piglets died in the farrowing units (18.3%). On the day of birth 26% of the piglets were cross fostered. Between day 2 and day 20 30% of the pigs were moved. The hazard ratio for cross fostered pigs was 0.77 compared to not cross fostered pigs. This means that cross fostered pigs had approximately 23% lower risk dying before weaning. The hazard ratio for pigs moved from the second day was 2.49 compared to pigs that were not moved. This means that the moved pigs had approximately 2.5 times higher risk for dying before weaning. The hazard ratio for pigs with birth weights < 1 kg and 1.0-1.5 kg compared to pigs > 1.5 kg were 6.43 and 1.50, respectively.
This study indicates that cross fostering was associated with lower risk for preweaning mortality. Moving pigs from the second day and low birth weight was associated with higher risk for preweaning mortality.
Markku Johansen, Jan Dahl, Poul Baekbo. Effect of cross fostering on preweaning mortality. 24th International Pig Veterinary Society Congress. 2016.