Aurantiochytriumsp. meal as DHA source in Nile tilapia diet, part II: Body fatty acid retention and muscle fatty acid profile

Abstract

Nile tilapia juveniles (8.35 ± 0.80 g) were fed on four levels (0.0%; 0.5%; 1.0%; 2.0%, 4.0%) of Aurantiochytrium sp. meal (ALL-G-RICH™), a source of docosahexaenoic acid (DHA). The 1% Aurantiochytrium sp. meal diet was compared to a control diet, which contained the same amount of DHA as cod liver oil (CLO) at 1.7% diet. Groups of 25 fish were stocked in 100 L tanks and fed twice daily until apparent satiation, for 57 days, at 28°C. Increasing dietary Aurantiochytrium sp. meal reduced the body retention of DHA and n-3 polyunsaturated fatty acids (n-3 PUFA) but increased the body retention of alpha-linolenic (α-LNA), linoleic (LOA) and n-6 polyunsaturated fatty acids (n-6 PUFA). Fatty acid profile in tilapia muscle was affected by increasing dietary inclusions of Aurantiochytrium sp. meal, with an increase in DHA, α-LNA, n-3 PUFA and n-3 long chain-polyunsaturated fatty acids (n-3 LC-PUFA) but a decrease in monounsaturated fatty acids (MUFA), n-6 PUFA and n-6 long-chain polyunsaturated fatty acids (n-6 LC-PUFA). There was a larger body retention of DHA, α-LNA, LOA, n-3 PUFA and n-6 PUFA fatty acids and a higher percentage of DHA, n-3 PUFA and n-3 LC-PUFA in muscle fatty acid profile in fish fed on CLO diets than in those fed on 1% Aurantiochytrium sp. Therefore, Aurantiochytrium sp. meal is an alternative source of DHA for Nile tilapia diets.