A preliminary study of dietary protein requirement of juvenile marbled flounder (Pseudopleuronectes yokohamae)

Abstract

An 8-week feeding trial was conducted to determine the optimal dietary protein level for juvenile marbled flounder. Five semi-purified test diets were formulated to contain different protein levels (CP) including 42.7%, 47.4%, 53.3%, 58.8%, and 64.5% (dry matter), named as CP42.7, CP47.4, CP53.3, CP58.8, and CP64.5, respectively. Five hundred and twenty-five juveniles (6.0 ± 0.1 g) were randomly distributed into 15 tanks (300 L tanks), resulting in 35 fish per tank ( n = 3 tanks). Fish were fed the test diets 5 times per day until satiation. The CP58.8 resulted in the highest gain in weight and the best efficiency in feed utilization among the tested protein levels ( P < 0.05). Fish fed the CP58.8 diet showed significantly higher whole-body protein and lipid contents than the fish that were fed the other diets ( P < 0.05). Fish fed the CP53.3, CP58.8, and CP64.5 diets showed a significantly higher dorsal-muscle lipid content than the fish that were fed the CP42.7 and CP47.4 diets ( P < 0.05). The one-slope straight broken-line regression analysis on the results of the thermal growth coefficient and feed conversion ratio indicated that the estimated optimum dietary protein level was 58.8%. Taken together, it is suggested that the dietary protein level of 58.8% is optimal for better growth and high efficiency in feed utilization for the juvenile marbled flounder.

Digestible protein levels and metabolic responses in juvenile piapara (Megaleporinus obtusidens)

“…Generally, protein is the first nutrient considered when determining the nutritional requirements of fish species (Oliva-Teles et al, 2020;Cho et al, 2021;Qian et al, 2022). There are several species exploited in aquaculture that have different eating habits, live in different habitats and temperatures, and may grow slower or faster (NRC, 2011), directly reflecting different nutritional requirements.…”