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Can we predict which sows die?

On a farm with excellent labor and limited feeding competition in gestation, poor structural conformation did not have a high association with sow mortality.

March 2, 2023

3 Min Read
Sow card.jpg
National Pork Board

Sow death loss continues to be an animal well-being, economic and sustainability challenge for pig farmers. The majority of sow death loss occurs during late gestation and lactation. Unborn piglets are not able to survive when a sow dies in late gestation. During lactation, sow death (depending on stage of lactation) reduces the availability of colostrum, milk and functional teats to a batch of piglets. Hence, sow mortality impedes reproductive throughput.

We characterized sow mortality at a 2,600 head commercial sow farm in eastern North Carolina over a 27-week period. The selected farm had a high quality labor force, one of the best I have worked with. Sows were housed in individual stalls during gestation. In late gestation, sows were evaluated for abnormalities (i.e. structural conformation, overgrown toes and dew claws, perineal swelling, behavior, etc.). Farm recorded sow mortality codes included difficult farrow (7%), lameness (32%), prolapse (21%) and unknown (40%). Of the 3,340 sows evaluated, 190 (5.7%) died between day 95 of gestation and 30 days post-farrow.

Recorded sow abnormalities are shown in Table 1 and Figure 1. Perineal swelling was recorded in late gestation for 57 sows. Of those 57 sows, 14 (24.6%) died by 30 days post-farrow. Sows with perineal swelling died due to lameness (two sows), prolapse (eight sows) and unknown (four sows). Therefore, perineal swelling was related to several sow mortality codes.

NC State Table 1 030223.JPG

Long toes or dew claws were noted on 27 sows. Of those, only 2 (7.4%) died between day 95 of gestation and 30 days post-farrow. Hence, on a farm with limited feeding competition in gestation, long toes and dew claws did not have a high association with sow mortality.

Swollen leg or injury was recorded for 16 sows. Of those 16 sows, 8 (50%) died by 30 days post-farrowing. The majority of those deaths were due to lameness (seven sows), yet one sow with a swollen rear hock died in late gestation of unknown causes.

Poor structural conformation was noted on only 14 sows. Visual observations suggest this particular production system has superior gilt structural conformation when compared to other production systems using the same genetics. Of the 14 sows with poor structural conformation, none died by day 30 post-farrow. Hence, on a farm with excellent labor and limited feeding competition in gestation, poor structural conformation did not have a high association with sow mortality.

NC State Fig 1 030223.JPG

Revisiting our original question, can we predict which sows die? The answer is yes and no. Yes, abnormalities were more likely to be recorded in late gestation for sows that died by 30 days post-farrow when compared to sows that lived (15.3 vs. 4.5%). However, abnormalities were not recorded for the majority (84.7%) of sows that died by 30 days post-farrow. Perhaps more abnormalities would have been noted if we would have evaluated sows more than a few times in late gestation.

Results from the current study challenge the author's paradigm that poor stockmanship and structural conformation are largely related to the sow U.S. sow mortality dilemma. While good stockmanship and proper structural conformation are still very important, there may be other, more important factors driving sow death loss.

The author would like to thank North Carolina pig production systems for their continued support towards characterizing and solving industry problems. Questions can be sent to Mark Knauer via email.

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