A high percentage of pigs born dead in litters in high-, intermediate- and low-performing herds.

The objectives of the present study were to measure a percentage of pigs born dead in the number of total pigs born (PPBD), and to investigate an association between PPBD and total pigs born by parity groups and three herd groups formed on the basis of the pigs weaned per mated female per 6 years (PWMFY). The studied data included 236,805 parity records of 51,443 sows in 110 herds. The three herd groups, high-, intermediate- and low-performing herds, were formed on the basis of the upper and lower 25th percentiles of PWMFY. Linear mixed-effects models were performed to analyze the data. Mean (+/- SEM) PPBD was 9.6 (+/- 0.03) %. Sows in high-performing herds had lower PPBD for all parity groups than those in low-performing herds (P<0.05). Parity 2 sows had the lowest PPBD between parity groups (P<0.05). The PPBD increased from 7.0 to 13.2% as the parity number increased from 2 to >or= 6. Parity 1 sows had higher PPBD than parity 2 and 3 sows (P<0.05). As the total pigs born increased from 10 to 16 pigs, PPBD increased in all the parity groups (P<0.05). In parity 3 or higher, PPBD in low-performing herds increased more steeply than that in high-performing herds as total pigs born increased form 6 to 10 pigs. We suggest that farrowing management including assisted farrowing improve PPBD for sows in parity 3 or higher.