Growth, Survival, Digestive Enzyme Activities, and RNA/DNA Ratio in Japanese Flounder Paralichthys olivaceus Larvae Fed Live Food and Casein Peptide- and Fish Meal-Based Microdiets

Abstract

A feeding experiment was conducted to investigate the effects of feeding live food (LF) and two microdiets [MDs; commercial MD (CD) and peptide-based MD (PMD)] on the growth, survival, digestive enzyme activity, and RNA/DNA ratio in Japanese flounder Paralichthys olivaceus larvae. Flounder larvae at 21 days post hatching (dph) were fed two types of MDs with 1/6 LF or LF for 18 days. At 38 dph, significantly higher survival was observed in larvae fed LF than those fed CD + 1/6 LF and PMD + 1/6 LF. At 38 dph, significantly higher body weight was observed in larvae fed CD + 1/6 LF than LF and PMD + 1/6 LF. Significantly higher RNA/DNA ratios were observed in larvae fed LF than CD+1/6 LF or PMD + 1/6 LF during 23-32 dph. However, there was no difference in RNA/DNA ratios in larvae fed CD+1/6 LF and PMD+1/6 LF at all time examined. Significantly higher amylase, lipase and trypsin activities were observed in fish fed 1/6 LF at 29 and 32 dph. Protease activity of fish fed 1/6 LF was significantly higher at 35 dph. No marked difference was observed in enzyme activities in fish fed two MDs.