The intensification of agricultural systems has increased yields and efficiencies, reducing environmental impacts and production costs. However, nutrient cycles have become dissociated in many agricultural systems, including swine production systems. Losses of nitrogen (N) and phosphorus (P) from manure lead to severe eutrophication and acidification problems in many regions of the world, as well as greenhouse gases emissions; but they are also essential nutrients for crop production. In a dissociated nutrient cycle, the use of mineral phosphate and urea as fertilizers becomes essential. For animal, P is essential for growth performance and bone mineralization. Additionally, since it is a limited and non-renewable resource produce by few countries, phosphate, dictates our capacity to produce food. Therefore, an efficient use of plant P by pigs and a consequent use of excreted P as fertilizer for crop production is necessary. N is also essential for animal and plant production. N is not a finite resource, but production of mineral N fertilizers requires a high energy input and protein-rich feedstuffs can have a high negative environmental impact depending on production context which requires to reduce N excesses. These environmental challenges are even-more relevant for competitiveness given the higher prices of raw materials and N and P inputs for feedstuffs in recent years. In consequence, there is an urgent need to optimize utilisation of resources such as P and N. To achieve this, an accurate and robust feeding system for P (including calcium (Ca) given their many interactions) and N (including amino acids (AA)) is needed. This involves setting up a system that 1) accurately and robustly determines the P, Ca and AA content of feed ingredients, 2) determines precisely the P, Ca and AA requirements of animals, 3) provides these nutrients to animals as accurately as possible and 4) integrates innovative feeding strategies to optimize their utilization by animals.
