Current demographic forecasts estimate that population growth will require a 70% increase in world food production by 2050. Achieving this goal in a sustainable way demands new sources of protein. Among these, marine algae are good candidates, as they do not compete for fresh water nor farmland, achieving higher protein productivity per unit area compared to terrestrial crops such as soybeans, legumes or wheat.
In addition to protein, seaweed is an excellent source of unsaturated fats, vitamins, pigments and micronutrients such as iodine, iron or zinc. They produce less CO2 emissions than other foods, eliminating nitrogen and phosphorus from the environment, releasing oxygen and contributing to the improvement of water quality. It is not surprising, therefore, that they have become the protagonists of multiple strategies focused on the search for sustainability.
Algae are usually classified as macro and microalgae, freshwater, brackish or marine. Among the marine macroalgae, three large groups are distinguished: green, brown and red algae. Some species of marine macroalgae contain such high levels of protein (up to 47% of the dry matter in nori seaweed) that are used as high-performance nutritional supplements. New uses are promoting their addition into pastas, breads, sweets and even healthy drinks. Although abundant in all essential aminoacids, seaweed proteins are typically rich in aspartic and glutamic acid, responsible for the fifth umami flavor, refined as glutamate from kombu seaweed. And many algal proteins, such as lectins or phycobiliproteins, have been shown to retain immunostimulating, anticancer, antibacterial, anti-inflammatory or antiviral properties.
With approximately 30,000 species of marine macroalgae described, accurate information on algal protein digestibility is still lacking. However, recent data show in vitro digestibilities of around 80%, particularly high for many red algae, placing them at similar levels and even higher than other vegetable sources, cereals or fruits. The use of thermal, enzymatic or other treatments (ultrasound, microwaves, electrical pulses) is improving the nutritional profile of many algae extracts, and facilitating their incorporation into animal feed. Just as it was done many centuries ago, algae are regaining their popularity as a sustainable ingredient for the nutrition of ruminants, pigs, poultry, fish and even pets.
Increased growth rates, greater meat juiciness, more intense flavors, elimination of antibiotics, improved digestive function, increased pigmentation, correction of the fat profile in milk, more resistant integuments and eggshells, healthier kidney function, weight control … many advantages are continuously reported as a result of the incorporation of algae in feed formulae. But very relevant physiological effects are also being identified, of such great impact which are likely to mark a turning point for the applications of algae in animal nutrition.
Recently it was found that the addition of small (<1%) amounts of certain algae in the feed of beef heifers reduced methane production by up to 80%, without altering the daily weight gain, carcass quality or the organoleptic properties of the meat. This is due to the presence of certain components in algae, such as bromochloromethane, which are capable of modifying the ruminal flora, favoring the development of non-methanogenic populations.
Methane is one of the main gases responsible for global warming, and it is estimated that livestock produces approximately 15% of the total emissions of this gas. This has been the subject of recent international commitments at the United Nations climate summit that took place this year in Glasgow, Scotland, as methane was considered responsible for approximately one third of the greenhouse effect. If successful, a relatively simple solution such as the inclusion of algae in the ration reducing methane production to such an extent is undoubtedly a welcome development for the sustainability of livestock production.
The administration of access rights, the scalability of industrial operations for algal processing, some aspects of food safety such as the bioaccumulation of certain heavy metals, the variability and seasonality of biomass and price are some of the limitations for the development of all these nutritional, environmental or pharmaceutical applications. Although there are plenty of opportunities as well. In Galicia in particular, with a large livestock population and associated environmental impact (emissions, slurry runoff, faecal contamination), the excreta resulting from the intensive monoculture of mussels, which translates into the sedimentation of huge amounts of sludge on the bottom of our estuaries, provides an obvious opportunity for the enhancement of an algal resource that is still very much undervalued.
We have incorporated for these reasons the reproduction of certain commercially relevant species of algae in the ECOPEMER project, a prototype for a new farming system focused on the production of shellfish and fish seed under recirculation. Using innovative containment and disinfection systems, and pursuing the ecological certification of the final product, the incorporation of algae to the multitrophic system improves the quality of the bivalve seed, and regulates key water quality parameters while providing a valuable output (macroalgae seedlings) for the restoration of seagrass meadows and eutrophic water bodies.
Overexploitation, pollution, eutrophication, embezzlement, politicization, emigration and unemployment … of these ingredients in southern Europe we have plenty. It is time to show that we also know about good management, taking advantage of opportunities and imagination. We just need they let us prove it.