Proteins are made of 20 amino acids. Fish break down the proteins to its basic components: free amino acids and small, short chains of amino acids called peptides. Fish utilise these amino acids to build their own proteins on which they grow.
Amino acids can be obtained from many resources, such as fish meal, land animal by-products or vegetables. What matters for utilising a raw material is the number of amino acids that are available to the fish. If one amino acid is missing to complete the right amino acid profile needed by the fish, it can be compensated for by choosing an additional raw material that has the missing part. Yet, the right amino acid profile determines the potential performance of the feed and thereby of the fish.
Furthermore, if fish digest the proteins but are unable to break down the components (free amino acids or peptides) these components will not be able to create growth. Therefore, in aquaculture feeds, the digestibility of the proteins is more important than the raw material they originate from.
Fish require nutrients, not raw materials. To ensure the desired performance of the feed and the fish, it is crucial to identify the right amino acids profile and the digestible protein levels of each raw material, and to ensure the ideal mix of raw materials required by the fish.