Phylloquinone CONTENT OF MACROALGAE FROM THE PORTUGUESE COASTAL AREAS
Very few studies so far have focused on the use of macroalgae as an ingredient in fish feeds to meet the dietary needs in micronutrients like vitamins or minerals. A balanced supply of micronutrients is essential for maximizing fish growth and survival rates, and preventing the incidence of skeletal deformities. Skeletal deformities are frequently observed in aquaculture produced fish, representing a major bottleneck for the industry. Optimizing feeding strategies allied to good husbandry and monitoring techniques are used to diminish the incidence of deformities1. Previous studies have shown that dietary supplementation with phylloquinone (vitamin K1; VK1) has beneficial effects in improving skeletal development and reducing the incidence of deformities, while also impacting in reproduction2,3. Macroalgae have been shown to have high concentrations of VK14, compared to land based vegetable resources. With this in mind, we determined the concentration of VK1 in several macroalgae species collected along the coast of Portugal to assess their potential as an alternative natural source of this vitamin for use in fish feed formulations.
Methods: Macroalgae were collected by snorkelling in the subtidal of several locations along the south and west coast of Portugal, including in the salt-marsh lagoon system of Ria Formosa (Algarve). After collection the algae were rinsed with fresh water, frozen and freeze dried protected from light. Four commercially off the shelf species were also included for analysis. Quantification of phylloquinone was performed using 500 mg of dried algae for extraction of liposoluble fraction followed by UPLC (AQUAGROUP).
Results and conclusion: The species P. Cartilagineum had the highest content of VK1, with values around 1000 mg/kg. P. raphelisiaum and S. vulgare followed up with values around 800. All other species had VK1 below 200, and consequently too low to be considered as a feed additive. The incorporation of P. cartilagineum at 5% in fish diets is capable of meeting VK1 requirements for fish growth and can be used to replace the use of the sinthetic menadione (VK3), while decreasing the previously observed hepatoxicity associated with its use, particularly in larvae and juveniles.
References: 1-Soares et al 2014. Chapter 7. in Diseases and Disorders of Finfish in Cage Culture; 2-Richard et al 2014. Marine Biotech. 16, 522-537; 3-Fernandez et al 2019. BBA 1863 (1): 39-51; 4-Kaila 2015. PhD thesis
Acknowledgements: This work was co-financed by the European Maritime and Fisheries Fund (EMFF/FEAMP) through the National Operational Programme MAR2020 (grant ALGASOLE-16-02-01-FMP-0058); and by the FCT (grant UID/Multi/04326/2019).
