Modern sows have been selected to increase prolificity in order to increase their productivity, writes animal nutrition expert Dr Francesc Molist. The continued increase in prolificity has resulted in a greater number of piglets born with a low body weight (< 1 kg). Based on this situation, Schothorst Feed Research (SFR) tried to answer the question of what has a greater effect on performance and economic result of the growing-finishing pigs; birth weight or weaning weight?