Quantification of the critical dietary requirements in the sulfur amino acid catabolic pathway in juvenile tilapia
In present study, four experiments were conducted to reevaluate the dietary requirements for methionine, choline, and phosphatidylcholine for juvenile Oreochromis niloticus. The ability of betaine to spare the requirement for dietary choline was also investigated. In Experiment 1, graded additions of L-methionine significantly affected weight gain, feed efficiency and serum methionine concentrations of juvenile tilapia, whereas survival and liver lipid concentrations were not significantly affected. The methionine requirement for tilapia with an initial weight of 3 g was 5 g methionine/kg dry diet. In Experiment 2, weight gain and feed efficiency of tilapia was significantly affected by dietary methionine while liver lipid concentration and serum methionine were not. The choline requirement for 3 g tilapia was 3 g choline/kg dry diet. In Experiment 3, addition of phosphatidy1choline significantly affected weight gain and feed efficiency of juvenile tilapia, while survival and total liver lipid concentrations were not significantly affected. The phosphatidylcholine requirement for tilapia with an initial weight of 12.1–12.7 g was 15 g phosphatidylcholine/kg dry diet. Weight gain and feed consumption were significantly affected in Experiment 4 by the dietary betaine. Betaine was able to replace the dietary requirement for choline in tilapia with an initial weight of 9.6 g. Data in the first two experiments was analyzed using a factorial design. In Experiments 3 and 4 data was analyzed by one-way ANOVA. Results from this study will be useful in least costs diet formulation for tilapia and support the introduction of tilapia as an animal model for homocysteine study.
0792: Fish production