Vegetable Oil Blends as Fish Oil Alternatives in the Diets of Heterobranchus longifilis Fingerlings

This study was undertaken to determine the suitability of vegetable oil blends as a major source of lipid in place of fish oil in the diet of Heterobranchus longifilis fingerlings. The fish were fed one of the six experimental diets twice daily to satiation for twelve weeks. The test diets were identical in composition, except for the source of supplemental lipid which was either fish oil (FO), palm oil (PO), soybean oil (SO), equal blend of FO and PO (FOPO), equal blend of PO and SO (POSO) or equal blend of FO, PO and SO (FOPOSO). The growth parameters were significantly different (P<0.05) among dietary treatments. However, the apparent digestibilities were not significantly different (P>0.05). Malic enzyme activities in the liver were not significantly different among dietary groups. On the other hand, the activities of glucose-6-phosphate dehydrogenase were significantly different and over six-fold higher malic enzyme. Results indicated that FO may be replaced with either PO, SO and their blends in H. longifilis diets.