Replacement of dietary fish oil with palm fatty acid distillate elevates tocopherol and tocotrienol concentrations and increases oxidative stability in the muscle of African catfish, Clarias gariepinus

Abstract

An 8-week feeding trial was conducted to determine the effect of substituting fish oil with palm fatty acid distillate (PFAD), a by-product from crude palm oil refining, on growth, feed utilization, vitamin E deposition, and oxidative stability in the muscles of African catfish. Five isonitrogenous, isoenergetic, and isolipidic (10%) practical diets were formulated to contain 0%, 25%, 50%, 75%, or 100% substitution of fish oil with PFAD. Growth of African catfish was significantly ( P<0.05) better in fish fed the 25% PFAD diet compared to fish fed the control diet, with fish oil as the sole lipid source. Higher levels of dietary PFAD supplementation did not cause further improvement in growth performance of catfish. Muscle concentrations of α-tocopherol, α-tocotrienol, and γ-tocotrienol increased linearly in response to increasing dietary concentrations originating from the added PFAD. α-Tocopherol constituted 68.5–80.2% of the vitamin E composition of catfish muscle, with total tocotrienols maintaining an equilibrium of 13.4–26.7% irrespective of dietary composition. Thiobarbituric acid-reactive substance (TBARS) concentrations in the muscles of catfish decreased significantly with increasing levels of dietary PFAD. The present study showed that the use of PFAD in catfish diets could offer protection against lipid peroxidation in muscles that would translate to longer shelf-life for seafood products. In fish meal-based diets for African catfish, PFAD can totally replace added fish oil. The use of PFAD is a practical and cost-effective way to produce high-energy diets without the damaging side effects of increased lipid radicals.