D.R. Tocher, G. Mourente, J.R. Sargent-1997
Aquaculture, 148: 213-231
Abstract:
Marine fish larvae have a requirement for large quantities of n-3 highly unsaturated fatty acids (HUFA), particularly docosahexaenoic acid (DHA; 22:6n-3), and dietary deficiencies of these induce a range of pathologies in fish including behavioural abnormalities. Therefore, there is a growing demand for natural lipids highly enriched in DHA as nutritional supplements during larval development. In the present study, DHA-rich products were obtained from fish neural tissues by a procedure involving ensiling in organic acids followed by neutralisation, drying, milling and sieving to produce the final particulate, crumbed products. Lipid content varied in the neural tissue silages from 5.5% to 46.5% but all lipid contained high percentages of DHA and high DHA:EPA (eicosapentaenoic acid; 20:5n-3) ratios ranging from 3.5 to 5.4. Tuna eye silage was a high lipid, high triacylglycerol (90.6% of total lipid) product and was particularly effective in increasing DHA content, outperforming a commercial product, in rotifer (Brachionus plicatilis) enrichment. Cod brain/eye silage had an intermediate content (18.2%) of lipid, which contained almost 50% as phospholipid, and proved as effective as a commercial enricher in increasing DHA content in Artemia nauplii. Moreover, Artemia nauplii, enriched with the cod brain/eye silage were more effective than nauplii enriched with a commercial enricher in increasing the DHA content of larval turbot brain. In conclusion, tuna eye and cod brain/eye silages are useful as enrichers of Artemia nauplii and rotifers for feeding marine fish larvae prior to weaning onto pelleted formulated diets.
(NERC Unit of Aquatic Biochemistry, Department of Biological and Molecular Sciences, University of Stirling, Stirling, FK9 4LA, UK)
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