Dietary Lysine and Arginine Requirements of Juvenile and Adult Zebrafish

Abstract

Use of zebrafish as a model organism in the biomedical field has increased dramatically in the past 20 years. Optimal culture conditions such as water temperature and water chemistry values have been established for zebrafish, while the development of a standardized diet has lagged behind. Failure to control dietary variables may influence experimental outcomes. In order for a standardized diet to be adequate, the feed must meet or exceed the zebrafish’s macronutrient requirements. To date, there has been no published data on quantitative macronutrient requirements of zebrafish. Two dose-response experiments utilizing isonitrogenous and isocaloric diets were performed in order to determine the dietary lysine and arginine requirements for zebrafish. Each experiment was divided into a juvenile and adult study. The dietary lysine requirement for juvenile and adult zebrafish was found to be 2.2% of dry diet and 5.6% of protein. The dietary arginine requirement for juvenile zebrafish was unable to be determined while the requirement for adult zebrafish was found to be 1.95% of dry diet and 6.5% of protein. Lysine-arginine antagonism was not observed in zebrafish. Plasma free arginine concentrations remained relatively stable in zebrafish fed diets ranging from 0.80 to 2.70% arginine. Plasma free proline decreased with decreasing dietary arginine, suggesting proline is being scavenged to synthesize arginine. In the future, adjustments should be made to experimental diet formulation with the goal of achieving growth performance similar to that of a reference diet.