Replacement of fish oil with vegetable oils in diets for jundiá ( Rhamdia quelen Quoy and Gaimard 1824): effects on performance and whole body fatty acid composition.

The jundiá ( Rhamdia quelen) is a siluriform with great potential for aquaculture in South America. Fish oil is a raw material in diets for fish. However, the fisheries that provide fish oil have reached their limit of sustainability. Thus, the use of alternative sources for this ingredient is primordial. The aim of this study was to evaluate the performance and body composition of the jundiá fed with different sources of the vegetable oils. Jundiá (1.0±0.2 g) were fed for 31 days with five isonitrogenous (37%) and isoenergetic (19 kJ g−1) diets, in which the following oils were added: 50 g kg−1 corn oil (CO), 50 g kg−1 fish oil (FO), 50 g kg−1 linseed oil (LO), 33.4 g kg−1 fish oil and 16.7 g kg−1 linseed oil (1/3LO), 16.7 g kg−1 fish oil and 33.4 g kg−1 linseed oil (2/3LO). The performance did not show differences between treatments. The final fatty acid profile and n-3/n-6 ratio of the fish were highly influenced by the diet. Fish-fed diets with linseed and/or fish oil showed superior n-3/n-6 ratios to the minimal recommended by the World Health Organization; whereas fish fed diets with corn oil showed an inferior value. Albeit in the present study the commercial size of fish was not attained, these results show a clear tendency. The desaturation/elongation capacity was evidenced, in this species, for the first time. Linseed oil can be utilized as a substitute for fish oil in diets of jundiá without affecting their performance and for producing good-quality fish. However, more studies are necessary to confirm these results for commercial size. [ABSTRACT FROM AUTHOR]