| Summary: | Postlarval (PL) Litopenaeus vannamei of 0.9 and 1.0 mg mean initial weight were reared for20 and 21 days in fiberglass tanks in experiments 1 and 2, respectively, to determine the optimal dietarycrude protein level for this species and growth stage reared in recirculating systems. Six semi-purified dietsformulated to contain crude protein levels of 10, 18, and 25 %, and crude lipid levels of 3 and 11 % wereevaluated in experiment 1. In experiment 2 semi-purified diets formulated to contain crude protein levels of5, 10, 15, 20, and 25 %, and 8 % crude lipid were evaluated. Mean PL survival in experiment 1 was notsignificantly affected by protein level, but was significantly lower for feeds containing 11 % lipid. Mean PLsurvival in experiment 2 was above 90% for all treatments and no significant differences were detected.Diets with 18 and 20 % protein level were adequate to provide similar PL growth as higher protein levels inthese culture conditions in experiments 1 and 2, respectively. Lipid level did not affect growth significantlyin experiment 1. Quadratic regression analysis of weight gain data for experiments 1 and 2 indicated theoptimal dietary crude protein level (Xmax) to be 21.4 % and 24.5 %, respectively, while broken-line analysisindicated to be 20.2 % and 21.5 %, respectively.
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