Performance of Macrobrachium rosenbergii broodstock fed diets with different fatty acid composition

The effect of Linoleic acid (18:2n - 6) and n - 3 highly unsaturated fatty acids (HUFA) on the reproductive performance and offspring quality of the f reshwater prawn Macrobrachium rosenbergii was evaluated in a 180-day trial. Three isonitrogenous and isolipidic diets containing different levels of f atty acids, high 18:2n - 6 and n - 3 HUFA concentrations, high 18:2n - 6 an d low n - 3 HUFA, and low 18:2n - 6 and n - 3 HUFA, were fed ad libitum to three groups of six females. Fecundity was improved by the addition of high er amounts of 18:2n - 6 (from 3 to 13 mg g(-1) DW). As a consequence of hig her fecundity, smaller eggs were obtained most likely because the number of oocytes competing for a limited amount of yolk was higher. The higher gona do-somatic index of females fed diets with high levels of 18:2n - 6 and n - 3 HUFA levels further supports this hypothesis. The fatty acid composition of the eggs reflected to some extent the composition of the diets. Eggs of females fed high levels of 18:2n - 6 and n - 3 HUFA had the highest n - 3 HUFA content and had increased hatchability. Eight-day-old larvae from fema les fed high levels of 18:2n - 6 and n - 3 HUFA tended to present a better stress tolerance when exposed to 100 mg 1(-1) total ammonia for 24 h. No ot her differences were detected among larval characteristics from the differe nt offspring groups. Results demonstrate that feeding M. rosenbergii broods tock with high levels of 18:2n - 6 and n - 3 HUFA (13 and 15 mg g(-1) DW, r espectively) improved fecundity, egg hatchability, and the overall quality of the larvae. (C) 1999 Elsevier Science B.V. All rights reserved.