Research in Health and Nutrition (RHN) Volume 2, 2014
www.seipub.org/rhn
Total Lipid and Fatty Acid Content of Tilapia(GIFT Strain) Grown in a SemiIntensive System: A Descriptive View Ahmed Al-Souti1*, Claereboudt M.1 Department of Marine Science and Fisheries, College of Agricultural and Marine Sciences Sultan Qaboos University, PO Box 34, Al-Khod 123 Muscat, Sultanate of Oman 1
souti@squ.edu.om; michelc@squ.edu.om Received 21 May, 2013; Accepted 10 Nov, 2013; Published 10 Apr, 2014 Š 2014 Science and Engineering Publishing Company
Abstract Although the beneficial effects of long chain polyunsaturated fatty acids (PUFA) are generally accredited to oils from marine species, the lipids from freshwater fish can serve as a valuable source of essential fatty acids. Compared with marine fish, freshwater fish, including tilapia, generally contain higher levels of short chain polyunsaturated fatty acids, as well as considerable amounts of 20:5 n-3 (EPA) and 22:6 n-3 (DHA). A balanced n-3/ n-6 PUFA supply provided by the lipids of freshwater fish is important for both rearing healthy fish and producing a valuable food for human. In this study, the total lipid and fatty acids content of semiintensively farmed, Genetically Improved Farmed Tilapia (GIFT) strain (Oreochromisniloticus) was examined and the fatty acids content of both natural and supplemented feeds was determined. Analytical results from commercial feed revealed n-3 PUFA levels of 1.9% of total fatty acids. Plankton samples contain similar total amounts of n-3 PUFA (2.0% of total fatty acids) whilst dorsal muscle (fillet) samples contain 4.8% of total n-3 fatty acids. These results suggest the accumulation of n-3 PUFA in the muscle lipids. The amounts of EPA and DHA acids in the dorsal muscle samples were 0.9 and 2.9% of total fatty acids respectively. These values exceed those reported elsewhere for Nile tilapia grown in intensive culture systems with no access to natural food and provide evidence of the key role of natural plankton as a dietary source of n-3 PUFA. Keywords: Fish Feeds; N-3 Fatty Acids; Gifttilapia
Introduction There are different culture systems for culturing tilapia. These are described as extensive; semiintensive and intensive culture systems. In extensive
culture systems; the farmed tilapia feeds exclusively on the natural productions (planktonic or benthic) which takes place in large bodies of water with low concentration of fish. In contrast to extensive culture; intensive culture is rearing the fish at high densities in which all the food is provided (manufactured diets). Semi-intensive culture is linked to both extensive and intensive culture. It consists of supplementing the natural production consumed by fish in ponds with manufactured diets; which increases the natural production (Barnabe; 1994). Aquaculture has becomes a major contributor to global's fish supplies as production from capture fisheries has declined. Indeed; farmed fish have become very important in maintaining high quality protein with health-promoting n-3 PUFA for the consumers. Wild tilapia and tilapia reared under the extensive conditions possess a more favorable fatty acid profile for human consumption; higher in 18:3n-3; 20:5n-3; and 22:6n-3; higher n-3/n-6 PUFA ratios; with lower proportions of 18:2n-6 (Karapanagiotidiset al.; 2006). The muscle tissue of intensively cultured fish is characterized by increased fat deposition that is mainly saturated; MUFA and 18:2n-6 (Karapanagiotidiset al.; 2006). As intensive and semiintensive culture systems; the amounts of n-3 depends on the ingredients of diets given to the fish either containing high or low amounts of n-3. The varied composition of algae constituting the diet of the herbivorous fishO. niloticus and the herbivorous– omnivorous fish Rutilusrutilus L.; appears to be the predominant factor affectingthe quality of FA and lipids in these fish (Ahlgrenet al.; 1996; Zenebeet al.;1998a). In contrast; apparently due to a limited diet;
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