Dairy-processing wastes as a replacement protein source in diets of rainbow trout

Dairy‐processing wastes, not previously used in domestic animal and fish feeds, were evaluated as a replacement protein source in the diet of rainbow trout (Salmo gairdneri). Dairy residue replaced 10% dried whey without reducing growth or feed efficiency, and feed costs were reduced. Growth and feeding efficiency were somewhat reduced when dairy‐processing wastes in the diet were 15 or 20%.