The objective of this study was to determine the effect of an Eco-friendly pig diet on nitrogen excretion, manure characteristics and ammonia emissions. We compared two different diets: a Control diet in accordance with practices in European commercial farms and an Eco-diet formulated with a multiobjective (MO) method considering nutrient requirements, feed cost and environmental impacts calculated by Life Cycle Assessment (LCA). At feed level, the Eco-diet reduced environmental impacts in comparison with the Control-diet. We did not observe any significant effect of the dietary treatment on growth performance (feed intake, daily gain, water consumption). Although N intake was similar between the two experimental groups, the N excretion in feces was higher with the Eco-diet than with the Control-diet. The urinary N excretion was similar between the two experimental groups. As a result, the repartition of N between feces and urine was different between the two experimental groups. We did not observe any effect of the dietary treatment on ammonia volatilisation from slurries in storage condition.