A commercial macroalgae extract in a plant-protein rich diet diminished saturated fatty acids of Oncorhynchus mykiss walbaum fillets

Leonardo Bruni,Giulia Secci,Simone Mancini,Filippo Faccenda,Giuliana Parisi

doi:10.1080/1828051x.2020.1745097

Leonardo Bruni, Giulia Secci + Show 3 more

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https://doi.org/10.1080/1828051x.2020.1745097

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Abstract

Seaweeds are considered novel feed ingredients, nutraceutical compounds and source of pigments and proteins. They appear to possess bioactive properties, such as hypolipidemic, antioxidant and immune-stimulative actions; furthermore, their proteins are considered just as nutritious as terrestrial vegetables. In the present work, rainbow trout (Oncorhynchus mykiss Walbaum) was fed for 95 days with three diets: a fishmeal-based positive control diet (C+), a vegetable protein-based negative control diet (C−) and a diet similar to C − where 5% of soybean concentrate was replaced by a commercial blend of seaweeds (T). The monitored parameters were fish performance, physical and marketable characteristics, fillet oxidative status and fatty acid content. The estimated indices of enzyme activities involved in lipid metabolism were calculated. Fish performances were reduced in C − and T fish; C − and T fillet fatty acid (FA) profiles globally showed the same pattern and were distinct from C+, i.e. with a lower content of polyunsaturated FAs and a higher content of monounsaturated and polyunsaturated n6 FAs; contrarywise, saturated FAs were significantly lower in T group in comparison to the other two groups (p < .01). The estimated indices of enzyme activity highlighted differences between dietary groups; desaturase activities of C18 and n3 FAs were higher in T in comparison to C− (p < .001). A slight impoverishment of antioxidant activity was found in T compared to C + group. Dietary seaweeds seemed to be capable of influencing fillet FA composition as well as the activity of enzymes related to lipid metabolism. Further studies in this regard are encouraged. Highlights Seaweeds are novel feed ingredients with nutraceutical properties Saturated fatty acids of rainbow trout fillets were lowered by seaweed inclusion in the diet Estimated desaturase activities of C18 and n3 fatty acids were higher in seaweed-fed trout

Highlights

The intensification and expansion of farmed fish production necessitate larger volumes of protein for feed formulation and in the last decades vegetable proteins have been the chief substitute of fishmeal
Summarising the obtained results, the colour indices seemed to differ between the three experimental diets, LÃ, aÃ and bÃ were lower in C þ in comparison to C À and T; the yellowness index showed the highest differences between the treatments
The fatty acid profile seemed to be similar between C À and T diets, but deeply different between C þ and the other two diets; SFA and PUFAn6 were lower, while PUFAn3 were higher in C þ in comparison to C À and T (Table 1), the n3/n6 ratio was higher in C þ diet in comparison to C À and T

Summary

Introduction

The intensification and expansion of farmed fish production necessitate larger volumes of protein for feed formulation and in the last decades vegetable proteins have been the chief substitute of fishmeal. Aquaculture industry takes particular consideration for this aspect as vegetable substitutes rarely have an optimal fatty acid (FA) profile and often contain antinutritive factors (Oliva-Teles et al 2015). Fish products are well-known for their high polyunsaturated fatty acid (PUFA) content and feed FA profile could negatively affect the fish characteristics. As counter-action, supplements and functional ingredients could be added to feeds in order to carry nutraceutical molecules and have been studied to leap over the hurdles carried by vegetable sources.

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