The new breeding goals for pigs are influenced by changes in societal opinions and in technological developments. Especially in the developed countries, societal concerns call for an improvement of health and welfare of sows and finishers. Therefore, pig breeding companies (e.g. Topigs Norsvin) extend the selection and breeding goal traits with longevity traits of sows and robustness traits of piglets. Longevity of sows is negatively influenced by the incidence of leg injuries and lameness and the incidence of uterine prolapses. These are heritable traits, e.g. the heritability for the incidence of uterine prolapses is 0.20-0.30. Robustness traits of finishers will be improved by selection for survival of piglets and finishers. Variation in daily feed intake is used as an indicator of robustness and expresses the resilience of an animal (less variation in daily feed intake = more robust and more resilience). Natural selection against the Porcine Reproductive and Respiratory Syndrome (PPRS) is under development and gene-editing (see chapter 7.9) is in this respect in discussion. The technique is promising in this respect, but the societal opinion is, at least in the European Union, negative.
The European Food Safety Authority (EFSA) express the societal concern in recommendations towards breeding companies for the welfare of pigs: to avoid excessive competition within a litter, the litter size should not exceed the number of functional teats of a sow. To improve the longevity of a sow the EFSA believes that the average number of piglets born alive should not exceed 12-14. Breeding companies should anticipate on free farrowing systems with selection on piglet weight and viability, and on maternal behavior, good leg conformation and good udder quality of sows.
Castration of boars is or will be banned in developed countries and therefore (genomic) selection against boar taint is required. Biting behavior is still a point of concern. Research is performed by breeding companies with video techniques to study behavior and to find the biters and the victims.
Fortunately, the technological developments create opportunities to record new selection traits intensively and to extend the breeding goal with new traits that meet societal wishes and improves health and welfare of sows and finishers.