Selective breeding for increasing pig litter sizes has created welfare tradeoffs between sow reproductive success and individual piglet viability and welfare outcomes.
Increasing litter size without corresponding improvements in piglet viability represents a welfare failure built into the genetic selection process. Each additional piglet born to a sow with insufficient teats or milk represents a piglet likely to experience hunger, competition, crushing, and higher mortality. Welfare-informed breeding requires balancing litter size against sow milk production capacity, teat number, and individual piglet birth weights. Progress is possible - some breeding companies now publish piglet mortality rates alongside other productivity metrics - but market pressures toward productivity continue to outweigh welfare considerations in many breeding programs.