Research in Zoology 2012, 2(5): 23-30 DOI: 10.5923/j.zoology.20120205.02 The Influence of Palm Oil and Extracted Fishmeal on Growth Performance and Tissue Fatty Acid Composition of Heterobranchus Longifilis Fingerlings T. O. Babalola 1,* , D. F. Apata 2 1 Department of Animal Science, Landmark University, Omu Aran, Nigeria 2 Department of Animal Production, University of Ilorin, Nigeria Abstract Little is known about the effects of the dietary intake of palm oil and extracted fishmeal on growth performance and tissue fatty acid composition of Heterobranchus longifilis. Twenty H. Longifilis fingerlings were allotted for each treatment tanks in triplicate groups at random and were fed ten isonitrogenous and isoenergetic diets during a 12-week feeding trial. Diets were prepared by replacing fish oil with palm oil (PO) at 0, 25, 50, 75 or 100% (of fish oil) in extracted and un-extracted fishmeal-based diets in a 2 x 5 factorial design. Feeding H. longifilis fingerling with various levels of PO did not result in differences in fish growth and feed utilization parameters (P > 0.05). This suggests that complete replacement of FO with PO can support growth comparable to a FO based diet. However, reduced growth and feed utilization parameter values were observed in H. longifilis fingerling fed un-extracted fishmeal-based diets (P < 0.05). Extraction of lipids from fishmeal resulted in lower concentration of tissue eicosapentaenoic acid, docosahexaenoic acid and total n-3 PUFA (p < 0.05). While the tissue concentration of saturated, monounsaturated, n-9, n-6 and 18:2n- 6 fatty acids increased in the extracted than the un-extracted groups (P < 0.05). PO and extracted fishmeal resulted in increased index of atherogenicity and index of thrombogenicity of the fillet (P < 0.05), but the value was less than 1.00 considered to be healthy for human consumer. From the results of this study we conclude that H. longifilis fingerling be fed diets containing PO and extracted fishmeal, to enhance fish growth, survival and feed efficiency. Keywords Growth Performance, Fatty Acids, Fish Oil, Palm Oil, Heterobranchus Longifilis, Fishmeal 1. Introduction Dietary lipids play an important role as a source of energy for fish growth and as carriers for fat soluble vitamins. Fish oil is widely used in the production of fish feed because of its high content in monounsaturated fatty acids (MUFA) used by fish as metabolic energy source and omega-3 long chain polyunsaturated fatty acids (n-3 lcPUFA) that are essential to biological structure, stress resistance, normal function of cell membranes and development of immunity in fish.[1, 2] The dynamic development of aquaculture with a global average growth rate of 8.8% per year since 1970[3] has resulted in increased demand for fish oil which has reached its limit of sustainability.[4[ On the contrary, production of global vegetable oil has steadily increased reaching a volume of 100 times more than fish oil.[5] Therefore, replacement of fish oil with vegetable oils appears to be a viable option given their availability, low cost and absence of dioxins and pollutants.[6 – 10]. * Corresponding author: tobabalola@yahoo.com (T.O. Babalola) Published online at http://journal.sapub.org/zoology Copyright © 2012 Scientific & Academic Publishing. All Rights Reserved Among the vegetable oils, palm oil (PO) is currently the most abundantly produced in the world.[11] PO contains high level of saturated fatty acids especially 16:0 and also contains monounsaturated fatty acids principally made up of 18;1n-9;[12] both classes of fatty acids are good sources of energy for fish.[13] Crude palm oil (CPO) has a deep orange-red colour due to the high content of carotenoids and is a rich source of vitamin E.[14] The use of palm oil at various levels in diets for catfish,[8, 15, 16] Atlantic salmon,[17] and climbing perch[18] resulted in growth and feed utilization efficiency comparable to fish fed with equivalent levels of dietary fish oil. Lim et al.[19] found that the inclusion of at least 8% CPO or RBDPO in African catfish diets significantly improved growth performance, dietary protein retention and fillet vitamin E concentration of this fish. In recent past, CPO and RBDPO have been evaluated as dietary lipids for fish and this was done in the presence of residual fish oil from the fishmeal component in the experimental diets.[16 - 19, 20] However, fishmeal contains approximately 10% fish oil as purchased, which might provide sufficient HUFA to meet the essential fatty acid requirement of H. longifilis and obviate the effects of the lipid of interest. In the present study, the nutritive value of palm oil as a