Climatic factors associated with abortion occurrences in Japanese commercial pig herds

Objectives were to determine climatic and production factors associated with abortions in commercial swine herds and to compare the reproductive performances and culling patterns between aborting and non-aborting females that were re-inseminated. There were 309,427 service records analyzed for 56,375 females entered into 100 herds. Climate data were obtained from 21 weather stations located close to the herds. Mean daily average temperatures (Tavg) for the 21-day pre-mating period for each female were combined with the female's reproductive data. Generalized linear model assessments were conducted for abortion risk per service. Abortion risk per service (±SE) was 0.7±0.06%, and mean value of Tavg (range) was 15.0 °C (-10.7 to 32.7 °C). Risk factors associated with an increased abortion risk per service were greater numbers of parities, delivering more stillbirth fetuses, greater mean Tavg for the 21-day pre-mating periods and re-servicing of females that did not get pregnant at the first servicing (P<0.05). Abortion risk per service for parities 1-5 increased by 0.1-0.3% when the Tavg increased from 20 to 30 °C (P<0.05), but there were no such associations for parities 0 and 6 or greater (P≥0.37). Aborting re-serviced females had 0.4 fewer pigs born alive than non-aborting re-serviced females (P<0.05). Also, 64.6% of all aborting females were culled for reproductive failure, compared with only 23.4% of non-aborting females. In conclusion, producers should closely monitor females at greater risk of aborting and apply more advanced cooling systems.