GROWTH PERFORMANCE AND FEED EFFICIENCY OF ADULT FLORIDA POMPANO Trachinotus carolinus FED SEMI-PURIFIED DIETS WITH GRADED LEVELS OF METHIONINE

Methionine is one of the first limiting EAAs in many fish diets, especially those containing higher levels of plant protein sources such as soybean meal, peanut meal and copra meal (Goff and Gatlin, 2004). Many investigators have reported the quantitative methionine requirements of commonly cultured fish species with a range from 18 to 40 g kg^-1.  More recently, Niu et al. (2013) reported the requirements of methionine in golden pompano, Trachinotus ovatus (10.6 g kg ^-1 diet). The results of this study are valuable, but the study was performed with small fish (initial body weight: 12.5 g - final body weight: 72 g). Our study focused on determining the growth performance and feed efficiency of large Florida Pompano, Trachinotus carolinus (initial weight: 208 ± 26 g - final weight: 505 ± 67 g) fed six semi-purified, isonitrogenous and isocaloric experimental diets with graded levels of methionine. The lowest inclusion of Met started at 5 g kg^-1 in Diet 1, which increased by increments of 2 g kg^-1 to the highest inclusion at 15 g kg^-1 in diet 6 (D1:5, D2:7, D3:9, D4:11, D5:13, D6:15). The six formulations all shared equal inclusion levels of four practical ingredients: Fishmeal at 125 g kg^-1, Regular Soybean Meal at 75 g kg^-1, Soy Protein Concentrate at 75 g kg^-1, and Wheat Flour at 120 g kg^-1. All fish were individually weighed and distributed to each of 18 polyethylene plastic tanks (1000 L).

Results indicated (Table 1) that after 60 days of culture, fish fed all diets exhibited excellent growth, comparable to commercial conditions.  The first results of our investigation suggest that Florida pompano adults perform well with respect to growth and feed efficiency with values of methionine at 5.0 g kg^-1. These values of methionine are below those published for Trachinotus ovatus juveniles.