Could a Manipulation of Dietary Nutrient Contents Including Phosphorous Affect Compensatory Growth of Juvenile Olive Flounder Paralichthys olivaceus?

Abstract

I hypothesized that the manipulation of dietary nutrient contents including phosphorous could affect compensatory growth of juvenile olive flounder, Paralichthys olivaceus. Thirty fish averaging 34.8 g per tank were randomly chosen and distributed into 15 flow-through 180-L tanks. Three experimental diets were prepared: the control (C) diet, high protein and lipid (HPL) diet, and HPL diet with supplementation of calcium phosphate-monobasic (HPLP). Five treatments were prepared in triplicate: fish were hand-fed daily with the C diet twice a day for 8 weeks (C-8W); fish were starved for 1 week, and then fed with the HPL or HPLP diets twice a day for 7 weeks, and referred to as HPL-7W and HPLP-7W, respectively; and fish were starved for 2 weeks, and then fed with the HPL or HPLP diets twice a day for 6 weeks, and referred to as HPL-6W and HPLP-6W, respectively. The body weight of fish with C-8W, HPL-7W and HPLP-7W treatments was higher than fish with HPL-6W and HPLP-6W treatments on week 2, 4 and 6 after an initiation of the trial. At the end of the 8-week trial, fish with HPLP-7W and HPL-7W treatments overcompensated, as compared to fish with C-8W treatment. Full compensation was not achieved in fish subjected to the 2-week feed deprivation (HPL-6W and HPLP-6W treatments). Overall feed intake by fish was proportional to weeks of feeding. Feed conversion ratio of fish with HPLP-7W, HPL-6W and HPLP-6W treatments was higher than fish with C-8W treatment. The study showed that dietary supplementation of protein and lipid resulted in overcompensation of juvenile olive flounder subjected to a 1-week feed deprivation, but not a 2-week feed deprivation. Additionally, dietary supplementation of phosphorous did not further improve compensatory growth of fish.