The effect of microdiet supplementation of dietary digestive enzymes and a hormone on growth and enzyme activity in yellow perch juveniles

Juvenile yellow perch Perca flavescens were evaluated to assess their needs for exogenous digestive enzyme and hormone supplementation in dry diets. Evidence exists to support the hypothesis that these supplements may assist young fish in digestion. Four diets were tested: a commercially available trout starter; an experimental diet based on high quality fish meals and squid meal; and the experimental diet supplemented with either 0.1% (by weight) bombesin (digestive tract neurohormone) or pancreatin (digestive enzyme extract). Fish fed all diets had similar growth. Survival was high and was not significantly different between treatments. Specific activities for both trypsin and chymotrypsin were not significantly different between diets, indicating that digestive enzyme supplementation was not necessary in tested juveniles. Specific activities for pepsin were also not significantly different between treatments, indicating supplementation of dry diets with the digestive hormone bombesin did not affect gastric enzyme secretion in yellow perch juveniles. we conclude that these juvenile fish have digestive tracts that are fully formed and that diet supplementation is unnecessary.