The retrospective index approach (Kanis et al., 2005) was
used to derive weights of traits related to welfare (PM,
WMI and LEGw). Total weights of these traits in scenario 3
were determined in order to make their genetic changes
positive. First, the effect of increasing one by one the
weight of sow's leg condition, piglet mortality and
weaning-to-mating interval, on the genetic response in
the breeding goal was performed to obtain the minimum
weight for the achievement of a gain in the trait. Secondly,
several combinations of weights on these three traits were
used to choose the breeding goal values corresponding to
improvement in all considered welfare traits.