Growth responses and fatty acid composition of juvenile prawns ( Macrobrachium rosenbergii) fed a prepared ration augmented with shrimp head oil

Abstract

A prepared shrimp food was impregnated at 3% by weight with oil extracted from heads of Penaeus setiferus. This procedure brought about a reduction in the level of ω6 fatty acids and an increase in the percentages of ω3 fatty acids and saturated acids in the diet. The lipid-augmented ration was fed to juvenile Macrobrachium rosenbergii for 12 weeks in the laboratory, with the unmodified diet as a control. Prawns fed the augmented diet grew significantly larger than those given the control feed, and this difference was apparent by the sixth week of the study. Final mean biomass (g prawn/m 2 of tank floor) and efficiency of food utilization in the experimental group were about twice that in the control. Survival in the two groups was similar throughout the study and averaged 71 and 68%, respectively, for the experimental and control animals at the end of the experiment. Prawns fed both rations contained in their tissues about the same percentage of ω3 fatty acids as their diets, indicating conservation of these dietary acids and/or biosynthesis. In contrast, the animals contained substantially less 18:2ω6 (linoleic acid) than their diets, and the data suggested that some of this fatty acid may have been utilized as an energy source. Also, animals fed the augmented diet contained about 15 times more carotenoid pigments than those given the control ration. The study suggests that ω3 fatty acids are important in the nutrition of M. rosenbergii and that prawn diets might be made more effective by increasing the relative proportion of ω3 fatty acids in their composition. Waste shrimp heads may be one suitable source of fatty acids and pigments for use in prepared diets for aquaculture.