Macroalgae as a sustainable aquafeed ingredient

Abstract

Macroalgae, commonly known as seaweed, offer a novel and added-value dietary ingredient in formulated diets for fish. Production of biomass can be achieved without reliance on expensive arable land, as seaweed may be collected from coastal regions or farmed. There are three taxonomic groups represented by the term 'macroalgae': Rhodophyta (red), Chlorophyta (green) and Phaeophyta (brown). Like terrestrial plants, nutritional content in macroalgae can vary greatly amongst species, genera, divisions, seasons and locations. Aside from their basic nutritional value, seaweeds contain a number of pigments, defensive and storage compounds, and secondary metabolites that could have beneficial effects on farmed fish. This review appraises the beneficial qualities of these macroalgae compounds and their potential for exploitation in commercial finfish feeds. The current knowledge of the effects of macroalgae inclusion in finfish diets is also addressed. From these >50 fish feeding studies that were analysed, enhancing trends in fish growth, physiology, stress resistance, immune system and fillet muscle quality were reported. However, only a small fraction of algal species have so far been investigated as potential components in finfish diets, and furthermore, this review has identified a number of knowledge gaps that current research has yet to address. To conclude, an appraisal is made of the possible technologies employed to exploit seaweeds to an industrial level through stabilising the algal meal, enhancing the digestibility and functional food properties.

Sequential bioprocessing of Ulva rigida to produce lignocellulolytic enzymes and to improve its nutritional value as aquaculture feed

“…Aquaculture industry still relies on fish meal (FM) and fish oil (FO) as main protein and lipid sources for carnivorous fish species (Tacon and Metian, 2015). Macroalgae are considered an add-value ingredient due to its content on long-chain polyunsaturated acids, vitamins, minerals, pigments and antioxidant compounds, but its dietary inclusion level may be limited due to the high content of NSP (Wan et al, 2018). Indeed, high dietary level of NSP may affect the viscosity and transit velocity rate of digesta, intestinal morphology, and gut microbiota, impairing the intestinal function (Sinha et al, 2011).…”

The Sustainability Conundrum of Fishmeal Substitution by Plant Ingredients in Shrimp Feeds

“…Strategic management and utilization of fish by-products shows potential for higher resource use efficiency of valuable marine resources [69]. Additionally, improvement of feed conversion ratios [2], side streams up to 30-40% of the global food system [28], and novel protein sources (microbial biomass [70], insects [71], yeast, microalgae [6], macroalgae [72], and macrophytes) might allow acceptable solutions to supplement high quality fishmeal [8,9,44]. On the other hand, farming up the food chain [Integrated Multi-Trophic Aquaculture (IMTA), biofloc aquaculture systems and aquamimicry] often require less biological resources and far less to almost no aquafeed input [73,74].…”

GC/MS identification and applications of bioactive seaweed extracts from Mediterranean coast of Egypt

“…Oliveira et al (2014) stated that addition of the brown algae Ascophyllum nodosum as meals to the diet of Nile tilapia infected with A. hydrophila enhanced the sanitary status of the fish and occurrence of the infection was lower. Previous studies reported in vivo antibacterial activity of water, methanol and dichloromethane extracts of different algal species against Vibrio anguillarum, Aeromonas salmonicida, Pseudomonas anguilliseptica, A. hydrophila, Yersinia ruckeri, and shrimp Vibrio pathogens for aquaculture sanitary (Bansemir et al, 2006, Manilal et al, 2012Rizzo et al, 2017;Wan et al, 2018).…”