ISSN 2375-0715
African Journal of Fisheries Science ISSN 2375-0715 Vol. 5 (3), pp. 238-248, March, 2017. © International Scholars Journals
Full Length Research Paper
Effect of varying dietary proportions of linseed and olive oils on fatty acid composition of Nile tilapia and African catfish under aquaponics culture system
1Omolo Kevin Mbogo*, 2Onyango Arnold, 1,5Magoma Gabriel, 3Munguti Jonathan,4Ogila Kenneth and 6Masinde WP
1Department of Biochemistry, Jomo Kenyatta University of Agriculture and Technology. P.O Box 62000-00200 Nairobi,
2Department of Food Science and Technology, Jomo Kenyatta University of Agriculture and Technology P.O Box 62000-00200 Nairobi,
3Kenya Marine & Fisheries Research Institute, National Aquaculture Research, Development & Training Center, Sagana. Kenya.P.O Box 451-10230 Sagana,
4Department of Zoology, Jomo Kenyatta University of Agriculture and Technology, P.O Box 62000-00200 Nairobi,
5Pan-African University, Institute for Basic Sciences , Technology and Innovation , P. O. Box 62000 00200 Nairobi,
6Department of Horticulture, Meru University of Science and Technology P.O Box 972-60200 Meru.
*Corresponding author E-mail: [email protected]
Accepted 03 February, 2017
Abstract
This study evaluated the effect of varying proportions of linseed and olive oils in fish diets on the fatty acid composition of tilapia and catfish liver and muscles under aquaponics culturing system after 150 days of feeding period. Experimental diets contained linseed, sunflower and olive oils at a varying composition of between 0 to 100% and commercial diet as a control feed (table 1). Gas chromatography was used to analyze fish tissue fatty acid profiles. Significantly high composition of n-3 fatty acids were observed in tilapia fed diet 1 (p<0.05) with DHA (C22.6) being the dominant n-3 fatty acids at 12.2% and 10.8% in tilapia muscles and liver respectively (table 4 and 5). In catfish, muscle and liver had 10.4% and 9.7% DHA content respectively (table 6 and 7). The muscle accumulation of n-3 fatty acid was significantly higher than liver in both fish species an efficiency in their retention and relative resistance of DHA to β-oxidation in the fish muscles. In both tilapia and catfish, the tissue n-3 fatty acids decreased with the reduction in linseed oil proportion in the diet feed suggesting direct influence of dietary oil composition on tissue fatty acid composition.
Keywords: Catfish, tilapia, DHA, EPA, n-3 fatty acids, linseed oil.