Causes and control of sow losses.

Pigs weaned/sow/year increases after the first litter to a maximum at about the third litter, after which it declines such that the sixth litter size is the same as the first, with a gradual decline thereafter. The cost of producing a weaned pig decreases with increasing numbers of litters weaned up to the third, then gradually increases. Average sow culling rates on commercial farms are 24-40% annually. The average time from weaning of pigs to culling of sows is 50-60 days. Sow mortality ranges between 2% and 14%, with a 6-8% average.