Utilization of Semipurified Diets by Tautog

Abstract

Abstract Experiments were conducted to determine whether semipurified diets would support growth in the tautog Tautoga onitis, a stomachless fish. Semipurified diets contained 50% protein and either 7% or 12% lipid on a dry-matter basis. A commercial salmonid feed containing 54% protein and 15% lipid on a dry-matter basis was used as a reference feed. Semipurified diets were either “as is,” with intrinsic pH of 5.5-5.8 or with pH adjusted during preparation to 7.2-7.6. Experiments were conducted with 6-13-g tautogs at 20°C for 28-31 d, and diets were fed at daily rates providing 14 g protein/kg body weight. Alkalinizing the 7%-lipid semipurified diet pH from 5.5 to 7.2 resulted in a significant (P < 0.05) increase in tautog growth rate. However, growth of tautogs fed the reference feed was significantly (P < 0.05) greater than growth achieved by fish fed either of the 7%-lipid semipurified diets. Semipurified diets containing 50% protein and 12% lipid supported growth in tautog at a rate comparable to the...