Effect of Starter Diet Lipid Levels on Growth and Body Composition of Juvenile Spring Chinook

Current commercially produced starter diets are formulated with high (18-20%) lipid content to meet hatchery production goals. High lipid diets may not be ideal for certain hatchery programs, such as those for conservation, where the goal is to produce phenotypes that resemble wild juveniles.  We investigated the effects of lipids in starter diets on growth and body composition of spring Chinook (Oncorhynchus tshawytscha) to identify diets that produced fish that more closely resembled wild fish. Triplicate groups of fish (average starting weight 0.37g) were fed four experimental diets (4-6%, 8-9%, 11-12%, 18-20% lipid) and were compared to the commercially available starter diet (18-20% lipid) until they reached a size (3.0g) that was no longer supported by starter feed. At completion growth and body composition were compared across all five treatments. The results of this study provide important information for the feasibility of using low lipid starter diets to best emulate wild fish phenotypes, and are necessary for ongoing studies that rely on fish that more closely resemble their wild counterparts.