In highly intensive pig production areas, manure disposal is a major problem especially for nitrogen, because of water pollution by nitrates and air pollution by gaseous ammonia emissions. The situations in three European countries (Denmark, The Netherlands and France) were compared, on average, it was estimated that 17 to 19% of N intake is excreted in the faeces, and 45 to 50% in the urine, corresponding to a total excretion of 65 to 67% of intake. The growing pig period has the major contribution to N excretion (72%) as compared to 18 and 10% for sows and weaners, respectively. The amount of N in the slurry can be predicted precisely from the protein intake and the performance of the pigs. It is possible to reduce N output through modifications in the feeding strategy. A better adaptation of the diets to each physiological or growing stage, and the improvement of protein quality through the use of industrial amino acids are two complementary approaches for reducing N excretion. With these cumulative beneficial effects, it may be expected that N output in the slurry and in the atmosphere can be reduced by 20 to 30% through better feeding management. The research that is carried out in the different countries on the evaluation of protein availability in feedstuffs and amino acid requirements, and the development of computerised pig models, should allow further reductions of N excretion, and promote the use of low protein feeding strategies in practice.