Performance of Rainbow Trout as Affected by Amount of Dietary Protein and Feeding Rate

Abstract

Abstract Rainbow trout (Salmo gairdneri) with an initial average weight of 13 g were fed four experimental dry pelleted diets (1-4) and a commercial trout feed at a hatchery constant of 18 for 266 d, 23 for 244 d, or 28 for 196 d. The components of diets 1-4 included about 13% crude fat and 23.9-38.5% crude protein (19.7-31.9% digestible protein). The minimum amounts of dietary crude protein and digestible protein required for satisfactory fish performance were near 33 and 28%, respectively, with 13% dietary fat. Weight gain, feed conversion, and percent dress-out weight of fish fed this diet were equal to or better than those noted for fish fed any other diet at a hatchery constant of 28. The feed cost per kilogram of fish produced was somewhat lower for fish fed this diet than any other diet at the three feeding rates. Manipulating the growth rate of rainbow trout by altering the diet formulation is far less efficient and less economical than feeding a single diet with an optimum amount of protein and fat within a range of feeding rates.