Plots of average daily weight gain (period: post-vaccination to necropsy), of pigs after challenge with virulent
strain B204, preceded either (green) or not (yellow) by exposure to non-virulent
strain D28, grouped by individual type (seeder, receiver and both) and by vaccination treatment. Boxes indicate 25 and 75% quantiles: bars indicate 2.5 and 97.5% quantiles. Average daily weight gain given in kg.