Quantification of fatty acids in tilapia fingerlings (Oreochromis niloticus) fed with different sources of vegetable oils<br>Quantificação de ácidos graxos de alevinos de tilápia do Nilo (Oreochromis niloticus) alimentados com diferentes fontes de óleos vegetais

The present work aimed to quantify the fatty acids in total lipids of Nile tilapia fingerlings (Oreochromis niloticus) fed with different sources of vegetable oils mechanically extracted. Were used 320 tilapias (O. niloticus) with average initial weight and average total initial length of 2.55±0.57 g and 5.59±0.43 cm, respectively, fed for a period of 60 days, in a randomized block design with eight treatments and four replications. The diets were prepared with 320 g/kg crude protein and 3.500 kcal of digestible energy per kg of feed enriched with eight different oils: sunflower, canola, sesame, linseed, peanut, Para’s nut soy and macadamia, with an addition of 4%. Among the major fatty acids the oleic, palmitic, linolenic and linoleic were obtained in higher concentration (mg/g of LT) in fish from all treatments. The sums of polyunsaturated fatty acids after 60 days of cultivation had increased in all treatments compared to the 30 days of the experiment. This is due to the addition of oils with high contents of n-6 and n-3 fatty acids. The fatty acids in the carcass are a reflection of the energy source of oil used. As a conclusion it is recommended the use of linseed oil in the diet of tilapia fingerlings due to great improvement in the relationship between n-6/n-3.<p><p> O presente trabalho teve como objetivo quantificar os ácidos graxos nos alevinos de tilápias do Nilo (Oreochromis niloticus) alimentadas com diferentes fontes de óleos vegetais extraídos mecanicamente. Foram utilizadas 320 tilápias com peso inicial médio e comprimento total inicial médio de 2,55±0,57 g e 5,59±0,43 cm, respectivamente, alimentados por um período de 60 dias, num delineamento em blocos casualizados com oito tratamentos e quatro repetições. As rações foram elaboradas com 320 g/ kg proteína bruta (PB) e 3.500 kcal de energia digestível (ED) por kg de ração, enriquecidas com oito diferentes óleos: girassol, canola, gergelim, linhaça, amendoim, castanha do Pará, soja e macadâmia, com uma inclusão de 4%. Dentre os ácidos graxos majoritários o oléico, palmítico, linolênico e linoléico foram os obtidos em maior concentração (mg/g de LT) nos peixes em todos os tratamentos. As somatórias dos ácidos graxos poliinsaturados aos 60 dias de cultivo apresentaram aumento em todos os tratamentos em comparação aos 30 dias de experimento. Isto se deve a adição dos óleos com alto conteúdo de ácidos graxos n-6 e n-3 nas rações. Os ácidos graxos na carcaça são o reflexo da fonte energética de óleo utilizada. Como conclusão recomenda-se o uso do óleo de linhaça na alimentação de alevinos de tilápias, devido à grande melhoria na razão entre n-6/n-3

Incorporation of conjugated linoleic acid (CLA) and &#945;-linolenic acid (LNA) in pacu fillets

The objective of this study was to evaluate the incorporation of conjugated linoleic acid and &#945;-linolenic acid in fillets of pacu fish raised in net cages and fed diets enriched with these acids. The fish were fed for 49 days, and at the end of this period the fatty acid content in the fillets was determined by gas chromatography. Concentrations of &#945;-linolenic acid, eicosapentaenoic acid, and the total omega-3 (n-3) fatty acid in the fillets increased, improving the n-6/n-3 ratio. In addition, the incorporation of conjugated linoleic acid in the fish fillets proved well established. This study showed that the use of diets enriched with conjugated linoleic acid and &#945;-linolenic acid results in the incorporation of these acids in the of pacu fish fillets, improving their nutritional quality