Performance of <i>Macrobrachium rosenbergii</i> 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 freshwater prawn Macrobrachium rosenbergii was evaluated in a 180-day trial. Three isonitrogenous and isolipidic diets containing different levels of fatty acids, high 18:2n-6 and n-3 HUFA concentrations, high 18:2n-6 and 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 higher amounts of 18:2n-6 (from 3 to 13 mg g-1 DW). As a consequence of higher fecundity, smaller eggs were obtained most likely because the number of oocytes competing for a limited amount of yolk was higher. The higher gonado-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 females fed high levels of 18:2n-6 and n-3 HUFA tended to present a better stress tolerance when exposed to 100 mg l-1 total ammonia for 24 h. No other differences were detected among larval characteristics from the different offspring groups. Results demonstrate that feeding M. rosenbergii broodstock with high levels of 18:2n-6 and n-3 HUFA (13 and 15 mg g-1 DW, respectively) improved fecundity, egg hatchability, and the overall quality of the larvae