Weaning is a critical process in piglets, with increased risk of health problems and decreased performance. Previous studies have shown that fish oil, rich in long chain omega-3 fatty acids, has an anti-inflammatory effect in pigs, which has led to improved pig performance under infectious challenge conditions (Liu et al. 2003). When piglets are weaned onto diets containing plant proteins, local inflammatory responses in the gut can reduce feed intake and performance. This study was designed to investigate the effect of Docosahexaenoic Acid (DHA) edible algae, as an omega-3 fatty acid source, in sow lactation and piglet post-weaning diets on piglet health and performance, when diets of different potential antigenicity were fed after weaning. It was hypothesised that increased omega-3 intake, either in sows’ milk before weaning or in the diet at the time of weaning, might facilitate the transition to solid food.