Fatty acid composition of acid, biological and enzymatic fish silage

ABSTRACT

The use of the fish silage as an ingredient in feed for aquatic organisms is an alternative to solve sanitary and environmental problems caused by the lack of an adequate destination for the residues generated by the fishing industry. It would also lower the costs with feed, and consequently the fish production costs, since the expenses with the fedd account for approximately 60 per cent of the total cost. The objective of this study was to evaluate the fatty acid composition of the acid silage (AS), biological silage (BS) and enzymatic silage (ES) produced from discardings of the culture and from processing residues of the Nile tilapia(Oreochromis niloticus). The values found for lipids (dry matter basis) were 12.45; 12.25 and 12.17 g 100 g-1 for BS, AS and ES, respectivelly. The fatty acids present in the lipid fraction of the silages are predominantly unsaturated. Oleic acid was present inlarger amounts (30.49, 28.60 and 30.60 g 100 g-1 of lipids for BS, AS and ES, respectivelly. Amoung saturated fatty acids, palmitic and stearic acids were present in larger amounts. Only traces of eicosapentaenoic (EPA) and docosahexaenoic from discardings of the culture and processing residues of the Nile tilapia are not a good source of EPA and DHA for fish feeds.