EFFECTS OF SALINITY AND DIETARY DHA (22 6N-3) CONTENT ON LIPID-COMPOSITION AND PERFORMANCE OF PENAEUS-KERATHURUS POSTLARVAE/

A two-way ANOVA experiment was designed to study the effects of salini ty and dietary docosahexaenoic acid (DHA; 22:6n-3) on lipid compositio n and performance of postlarvae from the marine shrimp Penaeus kerathu rus (Forskal, 1775). Shrimp were reared from 1- to 8-d-old postlarvae at 35 and 25 parts per thousand S with Kelko-enriched Artemia sp. [20. 0 mu g (n-3)HUFA mg(-1) dry weight; 9.1 mu g DHA mg-l dry weight] and nonenriched Artemia sp. [14.2 mu g (n-3) HUFA mg(-1) dry weight; 0.3 m u g DHA mg(-1) dry weight]. Dietary DHA content did not affect either total length or survival but influenced the nutritional status represe nted by condition indices (triacylglycerol/total polar lipid and triac ylglycerol/free cholesterol) of 8-d-old postlarvae at the end of the e xperiment. Culture salinity affected final total length and condition indices but did not show any effect on survival in the different exper imental treatments. The interaction of dietary DHA and culture salinit y was not significant for total length and survival but was significan t for both condition indices used. P. kerathurus 8-d-old postlarvae sh owed better growth, survival and nutritional condition when reared at 35 parts per thousand S and when fed on Kelko-enriched Artemia sp., bu t the differences with postlarvae from other treatments were very poor ly marked. The results demonstrate that 8-d-old postlarvae may have su fficiently developed osmoregulatory capabilities to resist 25 parts pe r thousand S under good conditions, although (n-3) HUFA-enriched diets may also enhance osmotic stress resistance, general performance and d isease resistance.