Partial replacement of fish oil by flaxseed oil in Atlantic halibut (Hippoglossus hippoglossus L.) diets: effects on growth,nutritional and sensory quality |
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Authors: | D ALVES MARTINS LMP VALENTE SP LALL |
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Institution: | 1. ICBAS – Instituto de Ciências Biomédicas Abel Salazar and CIIMAR/CIMAR – Centro Interdisciplinar de Investiga??o Marinha e Ambiental, Universidade do Porto, Porto, Portugal;2. National Research Council of Canada, Institute for Marine Biosciences, Halifax, NS, Canada;3. National Research Council of Canada, Institute for Marine Biosciences, Halifax, NS, Canada |
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Abstract: | Three isonitrogenous (520 g protein kg?1 DM) and isoenergetic (25 MJ kg?1 DM) diets containing increasing levels of flaxseed oil (FxO; 0%, 40% and 70% of total added oil) at the expense of fish oil (FO) were tested for 33 weeks in groups of 61 individually PIT‐tagged halibut (initial weight, 849 ± 99 g). Effects on fish growth performance, fillet nutritional and sensory quality were determined. Specific growth rate (0.2% day?1), feed conversion ratio (1.2–1.3) and nitrogen and energy retention were not affected by dietary treatments. Dietary fatty acid composition was reflected in fatty acid profiles of halibut muscle, liver and heart. Muscle of fish fed FxO diets contained higher 18:2n‐6 and 18:3n‐3 concentrations whereas 20:5n‐3 and 22:6n‐3 levels were significantly reduced. However, increasing FO replacement induced preferential retention of 22:6n‐3 especially in heart, and a trend for 20:5n‐3 conservation in heart and muscle was observed. FO replacement did not affect colour, texture and the characteristic fish odour and flavour of cooked fillets. By selectively retaining long‐chain polyunsaturated fatty acids halibut can adapt to a lower dietary supply without adverse effects on growth, feed conversion ratio, survival, and fillet nutritional and sensory quality. |
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Keywords: | Atlantic halibut fish oil flaxseed oil growth nutritional quality organoleptic quality |
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