Effect of green wavelength light on stress and appetite responses of olive flounder (Paralichthys olivaceus) following feed deprivation and re-feeding
Cheol Young Choi, Jin Ah Song, Tae Ho Lee, Young‐Su Park
Abstract
Feeding regimes and light may influence the productivity and wellbeing of aquatic animals; however, little is known regarding any interactive effects. We investigated if short-term deprivation and refeeding regimes and green light promotes growth by reducing stress in the olive flounder, using two lights [white fluorescent bulb (white) and green-wavelength LED (green)] in 4 feeding trials (fed 4 weeks, 4F; fasted 1 week/fed 3 weeks, 1S-3F; fasted 2 weeks/fed 2 weeks, 2S-2F; fasted 4 weeks, 4S). At the end of the feeding periods, weight gain rate (WGR), daily feed intake (DFI), and cumulative food intake (CFI) of 4F green group were significantly higher than other groups (p < 0.05), and the 1S-3F green group reached the WGR and DFI of the 4F white group (p> 0.05). Also, 1S-3F green group showed the highest values in feed efficiency (FE) (p < 0.05). In addition, mRNA expressions of neuropeptide Y (NPY), melanin concentrating hormone (MCH), and insulin like growth factor (IGF-1) were significantly higher in the 1S-3F green group at 4 weeks than in the other periods (p < 0.05). Immunohistochemistry (IHC) staining of NPY in diencephalon revealed that the brown colored increased with longer fasting period under white light. These results suggested that the 1S-3F feeding regime in the short term (4 weeks) was the most effective for short-term feed deprivation and re-feeding. Furthermore, green light had an especially beneficial effect that reduced stress and promoted appetite for refeeding in cultured fish. Our findings are expected to work toward a positive aquaculture environment for animal welfare.