Why reforming extreme litter size selection in commercial pigs is a welfare imperative and what better breeding objectives look like.
Litter size reform in commercial pigs requires confronting a case where one production metric — total piglets born — has been pursued to the point of creating compounding welfare problems at multiple levels. The sow cannot nourish so many piglets effectively; the smallest piglets cannot access teats competitively; pre-weaning mortality becomes the inevitable consequence of a design that prioritises birth numbers over birth viability. The welfare case for selecting against extreme litter size — or at minimum selecting for adequate total teat number and colostrum production alongside litter size — is compelling. Some breeding companies have recognised this and are moderating their selection pressure, but the change is not yet widespread or rapid enough to match the welfare need.