Evaluating the dietary taurine requirement of hybrid striped bass, (Morone chrysops x M. saxatilis)

Abstract

A dietary requirement for the sulfonic acid taurine has been documented in many marine species. However, it has not been well studied in hybrid fish with freshwater and marine genes, such as the hybrid striped bass (Morone chrysops x M. saxatilis). Therefore, an 8-week feeding trial was conducted to evaluate the effects of various levels of dietary taurine on growth performance, health, and body composition of juvenile hybrid striped bass. Four diets were formulated from practical ingredients and supplemented with DL-methionine at 0.54% of dry weight to meet the hybrid striped bass' established total sulfur amino acid requirement of 1.0% of dry diet, and taurine was supplemented incrementally at 0, 0.5, 1, and 2% of dry weight. Two additional diets were prepared without DL-methionine supplementation to be marginally deficient in methionine (0.49% by weight) and either supplemented with or without taurine at 1% dry weight to evaluate the potential interactions between methionine and taurine. Diets containing increment levels of taurine were determined to show no significant (P > .05) differences in terms of weight gain, feed efficiency (FE), whole-body composition, hepatosomatic index (HSI), intraperitoneal fat ratio (IPF ratio), or muscle yield. However, hybrid striped bass fed the methionine-deficient diets had significantly (P < .05) reduced percentage weight gain and FE as well as reduced muscle yield and HSI compared to fish fed the methionine-supplemented diets. Interestingly, taurine inclusion at 1% in the diet containing 0.49% methionine increased weight gain and feed efficiency of fish compared to those fed the diet without supplemental taurine or methionine. These results indicated that growth performance and body composition of hybrid striped bass did not respond to taurine supplementation when dietary methionine was adequate but did respond when dietary methionine was limiting.