Identification of feeding stimulants from a jack mackerel muscle extract for young yellowtail Seriola quinqueradiata

The feeding-stimulatory components of an aqueous extract of jack mackerel w hite muscle for young yellowtail were identified. The extract was fractiona ted using anion-exchange chromatography, and the feeding-stimulatory effect iveness of fractionated components examined by adding them to starch pellet s and feeding to yellowtail. The filtrate (FE) of the muscle extract filter ed through a membrane having a mol. wt. cut-off of 10,000 Da was found to h ave a high feeding-stimulatory effectiveness on the yellowtail. FE was frac tionated using DEAE-Sephadex A-25 at pH 5.5. The DEAE-Sephadex adsorbate (A (A)) showed an effectiveness close to but slightly weaker than that of FE. The DEAE-Sephadex non-adsorbate (N-A) had no appreciable effect. Subdividin g A(A) components by stepwise elutions with NaCl solutions suggested that i nosine-5'-monophosphate and lactic acid were largely responsible for the st imulatory effectiveness of A,. Some components in NA might also be synergis tic with A, components to elicit the full effectiveness of FE. (C) 2000 Els evier Science B.V. All rights reserved.