Challenging phosphorus requirement of large Atlantic salmon

Offentlig prosjektsammendrag

For adequate bone mineralisation dietary phosphorus (P) intake is essential in vertebrates. P deficiency can cause growth retardation and bone deformities in Atl. salmon. Historically, fishmeal is a good dietary P source to avoid such problems in Atl. salmon. To increase the sustainability of salmon aquaculture feeds with lower fishmeal content but higher inclusion of vegetable protein were introduced. It became common practice to add high available mineral phosphorus sources to the feeds to cover the essential P requirement of Atl. salmon. Addition of these high available P products is oriented to meet similar or even higher available P levels compared to a fishmeal rich diet. Comparing the development of the whole body P content of Atl. salmon, raised in seawater from 75 g to 5000 g, with the dietary P intake, revealed that approximately 35% of the dietary P is retained in the body. As phosphorus is mainly used for bone mineralisation and only little for metabolic purposes it must be assumed that nearly 75% of the dietary phosphorus is secreted via gills and feces into the environment. The main objective of this research project is therefore to investigate the effect of a dietary P reduction on growth performance, bone mineralisation and spinal deformities in large Atl. salmon.