Effects of dietary vegetable oil supplementation on fillet quality traits, chemical and fatty acid composition of African catfish (Clarias gariepinus)

Abstract. The effects of dietary fish oil (FO), soybean oil (SO) and linseed oil (LO) (12 % crude fat content each) in African catfish (Clarias gariepinus) diets were tested on the fillet flesh quality, chemical and fatty acid (FA) composition, after 3 and 6 weeks of feeding. The bodyweight gain of fish and the fillet dry matter, crude protein and crude fat content was not different among the divergent treatments. High (>20 %) total n3 FA supplementation significantly increased the moisture loss of fillet (FO, LO). Applying the simple FA dilution model (JOBLING 2004a, 2004b), the incorporation dynamics of the most largely dosed FAs were accurately predictable after 3 weeks (R² between observed and estimated data for total n3 FAs: FO 0.95, LO 0.73 and for α-linolenic acid, LO 0.97). In the fillet FA composition the metabolism of n3 acids was more pronounced. The large provision of α-linolenic acid (LO) had a pronounced effect on the longchain, polyunsaturated n3 FA proportions (eicosapentaenoic and docosapentaenoic acids), while no effect was experienced on docosahexaenoic acid. This study suggests that daily bodyweight gain is not, while fillet flesh quality and FA composition is slightly compromised when fish oil is substituted for vegetable oils.