Effect of Fish Meal Quality on Biological Performance of Juvenile Dolphin, Coryphaena hippurus

Abstract

Three feeding experiments were conducted to evaluate the effect of fish meal quality on biological performance of juvenile dolphin, Coryphaena hippurus, and to correlate performance with chemical quality indices. In Experiment 1, fish were fed isocaloric, isonitrogenous diets containing fish meals prepared From freshly killed, whole, sub-adult dolphin that had been stored for various lengths of time (0, 7, and 14 days) and processed either at 150°C, designated as high temperature (HT), or at 75°C, designated as low temperature (LT). Chemical quality indices of the raw material, the processed meal, and growth and feed utilization of fish were evaluated. In Experiment 2, similar diets were prepared and evaluated using four high-quality and three standard-quality commercial fish meals. In Experiment 3, the effect of mixing a high performance and a low performance commercial fish meal in various ratios was tested. Growth of juvenile dolphin varied inversely, and feed conversion varied directly with duration of raw fish storage and fish meal processing temperature (Experiment 1). High-quality commercial fish meals were better utilized by dolphin than standard-quality fish meals (Experiment 2). In both Experiments 1 and 2, biological performance correlated with available lysine, Torry pepsin digestibility, total volatile nitrogen, and free fatty acid values. Substituting a high performance with a low performance fish meal (Experiment 3) reduced growth and feed utilization proportionately. Results demonstrated that the chemical quality of fish meal used in diets for juvenile dolphin has a profound effect on overall diet acceptability and utilization. In order to maintain rapid growth and low feed conversion in this species, only diets made with high quality fish meals manufactured from fresh raw material and processed at low temperatures are recommended. The combination of several in vitro quality assays provided good indicators of fish performance.