THE EFFECT OF DIETARY N-3 HUFA AND 22 6N-3/20/5N-3 RATIO ON WHITE SHRIMP LARVAE AND POSTLARVAE/

The influence of varying dietary n-3 HUFA concentrations and ratios of 22:6n-3/20:5n-3 (DHA/EPA) on culture performance and fatty acid compo sition of white shrimp (Penaeus vannamei) larvae and postlarvae was ve rified in two experiments. In a first experiment, shrimp (zoea 2 - pos tlarvae 11) were fed rotifers (Brachionus plicatilis) and Artemia spp. nauplii that were enriched with different self-emulsifying concentrat es: one HUFA-free coconut oil (T1), and three iso-HUFA concentrates wi th DHA/EPA ratios of 0.6 (T2), 2 (T3) and 4 (T4), respectively. In a s econd experiment, postlarvae were fed for 25 days (starting from postl arvae 10) on isolipidic semi-purified diets: one HUFA-free control (TA ), and four iso-HUFA diets with DHA/EPA ratios of 0.6 (TB), 0.9 (TC), 1.8 (TD) and 3.64 (TE), respectively. Experiment 1 revealed no signifi cant differences in production characteristics, except that resistance to a countercurrent stress in postlarvae 11 was significantly lower i n T1 than in T2 and T3 (p < 0.05). In experiment 2, postlarvae of TA h ad a significantly lower dry weight than the other treatments at the e nd of the trial. The effect of the DHA/EPA ratio within the experiment al limits could not be demonstrated. Analysis of the fatty acid compos ition of the shrimp showed notable changes of n-3 HUFA concentrations during the metamorphosis from mysis to postlarvae, and a different res ponse to the dietary concentrations of DHA compared to EPA.