Seaweed at 3% to 8% of diets reduces disease, increases growth rates, and reduces inflammation and disease. Growth trials in Europe show improved yields, reduction in disease.
Farmers have given seaweed for lifestock for hundreds of years. But over the past few years agriculture has got interested not just for nutrition but also for health.
Diverse species of seaweed for livestock
Seaweeds are macroalgae, which generally reside in the littoral zone and can be of many different shapes, sizes, colours and composition. They include brown algae (Phaeophyceae), red algae (Rhodophyceae) and green algae (Chlorophyceae). Brown seaweeds have been more studied and are more exploited than other algae types for their use in animal feeding because of their large size and ease of harvesting. Brown algae are of lesser nutritional value than red and green algae, due to their lower protein content (up to approx. 14%) and higher mineral content; however brown algae contain a number of bioactive compounds. Red seaweeds are rich in crude protein (up to 50%) and green seaweeds also contain good protein content (up to 30%). Seaweeds contain a number of complex carbohydrates and polysaccharides. Brown algae contain alginates, sulphated fucose-containing polymers and laminarin; red algae contain agars, carrageenans, xylans, sulphated galactans and porphyrans; and green algae contain xylans and sulphated galactans. In ruminants, step-wise increase in the levels of seaweeds in the diet may enable rumen microbes to adapt and thus enhance energy availability from these complex carbohydrates. In monogastrics, those polysaccharides may impact the nutritional value but the addition of enzyme cocktails might help. In vivo studies on ruminants, pigs, poultry and rabbits reveal that some seaweeds have the potential to contribute to the protein and energy requirements of livestock, while others contain a number of bioactive compounds, which could be used as prebiotic for enhancing production and health status of both monogastric and ruminant livestock. Seaweeds tend to accumulate heavy metals (arsenic), iodine and other minerals, and feeding such seaweeds could deteriorate animal and human health. Regular monitoring of minerals in seaweeds would prevent toxic and other undesirable situations.
Nutrient Content of Seaweed
Seaweeds are rich in both macro and micro nutrients. They have a highly variable composition, depending on the species, time of collection and habitat, and on external conditions such as water temperature, light intensity and nutrient concentration in water. They may contain non-protein nitrogen, resulting in an overestimation of their protein content, and nitrogen-to-protein conversion factors lower than 6.25, normally used for feed ingredients, have been advocated. Red seaweeds are rich in crude protein and can be up to 50%. They contain considerable amount of water. Most essential amino acids are deficient in seaweeds except the sulphur containing amino acids. Seaweeds concentrate minerals from seawater and contain 10–20 times the minerals of land plants. They contain only small amounts of lipids (1–5%), but the majority of those lipids are polyunsaturated n-3 and n-6 fatty acids. The minerals in seaweed meal include potassium, phosphorus, magnesium, calcium, sodium, chlorine, and sulfur as well as the trace elements (elements required in trace amounts) zinc, cobalt, chromium, molybdenum, nickel, tin, vanadium, fluorine, and iodine. The mineral content of some seaweeds represents 30 percent of the dry matter weight. The vitamins in seaweed meal include ascorbic acid, tocopherols, and some B vitamins.
(from R.G. Abirami and S. Kowsalya 2010)
Heavy Metal Content in Seaweed for Livestock
BioSea Feed has not detectable heavy metals including arsenic, cadmium, mercury and lead, and all batches are tested for presence of heavy metals. R.G. Abirami and S. Kowsalya 2010 did detect some heavy metals with seaweed from Indonesia, but K alverezii have no detectable levels grown at current sites in Mindinao.
|Heavy metals (ppm)||Upper limits of human food in EU||Ulva Lactuca|
(from R.G. Abirami and S. Kowsalya 2010)
The literature is full of publications that seaweed has bioactive compounds, and activity against antifouling, antifungicidal, antibacterial properties. (The antibacterial properties of Asparagopsis sp with a high level of bromoform is the current focus on reducing methane reductions in ruminants).
Amino Acids in Seaweed for Livestock
The nutritional value of six tropical seaweeds (Sargassum wightii, Ulva lactuca, Kappaphycus alvarezii, Hypnea musciformis, Acanthophora spicifera and Gracilaria corticata) as complementary source of dietary, proteins for human and animal nutrition based on amino acid profile was evaluated. All these species showed similar non-essential amino acid patterns in which aspartic and glutamic acids constituted together a large part of the amino acid fraction (25.2% to 29.5%). All of them were generally rich in phenylalanine, tyrosine, threonine and tryptophan and deficient in methionine, cysteine, leucine and lysine.They generally showed a balanced amino acid profile comparable to FAO reference pattern. Seaweeds being rich in minerals, vitamins, polyunsaturated fatty acids as well as phycocolloids, partial substitution of costly protein sources in animal feeds with seaweed protein may improve feed quality while reducing the cost. Here is the Kappapycus and Gracilia analysis for comparison. Time of year maturity will all make a difference.
Some research says the nutritional value of seaweed as a feedstuff for poultry is satisfactory. Chemical analyses of dried marine red seaweed (Polysiphonia SPP) showed reasonable amounts of protein (32.4%); ether extract (17.7%), crude fiber (14.9%), ash (6.0%) and nitrogen free extract (23.4%). These authors concluded seaweed contained appropriate amounts of minerals required by poultry.
However, Alex Angell in 2016 says this is not correct. While seaweed has a high concentration and quality of protein, the reality is that seaweeds, irrespective of cultivation conditions and species are not viable as a protein source for monogastric (poultry and pigs). The levels become limiting and whole seaweed should be processed post harvest to concentrate into protein isolates and concentrates. It is clear that the other features of seaweed are contributing to the benefits from using seaweed as a feedstock; namely as a functional food with bioactive compounds.
Angell suggests that for Ulva (as an example) to extract salt, ulvans for pharmaceuticals, protein isolate and then use the remainder as residual. Solely using seaweed as a protein source would therefore discount the value of the bioactive compounds.
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Raymond Angell, A. (2016). Seaweeds as an alternative crop for the production of protein. James Cook University. Retrieved from http://researchonline.jcu.edu.au/46892/