What are microalgae used as feed?

Docosahexaenoic acid (DHA) is a long-chain polyunsaturated fatty acid with physiological functions such as brain health, vision improvement, anti-cancer, and improved immunity. Schizochytrium is a type of marine fungus with a large amount of DHA in its cells. Therefore, Schizochytrium is widely used in animal husbandry production as a feed additive.

Lipids are a type of nutrient essential for the survival and growth of organisms. They are important structural components of cell membranes and play an important role in energy storage in many organisms. Some polyunsaturated fatty acids are also important physiologically active substances. Among them, n-3 polyunsaturated fatty acids represented by DHA play an important role in the body's nutrition, health, and development. The traditional source of DHA is extracted from deep-sea fish oil, but this process has problems such as limited yield, difficult separation and purification, and high cost. Schizochytrium is a type of marine fungus belonging to the Thraustochytriaceae family. It is rich in DHA and its safety has been recognized by the FDA. Moreover, Schizochytrium can be cultured on a large scale under heterotrophic conditions, which is easy to commercialize, and the DHA content in its cells can also be controlled by culture medium and fermentation process. Therefore, Schizochytrium is an ideal new source of DHA.

The molecular formula of DHA is C₂₂H₃₀0₂, which contains 6 unsaturated bonds and is a key structure with many physiological functions. Since Horrocks et al. published an epidemiological survey in 1987 that showed that the incidence of coronary heart disease, myocardial infarction, and thrombosis among Eskimos was very low despite their large intake of marine lipids, research on DHA has developed rapidly.

Source of DHA and Schizochytrium

Currently, the main sources of DHA are marine fish and algal. Fish oil is the traditional source of DHA. Fish oil refers to oils and fats obtained from fish or fish processing waste. Fish oil with high DHA content is mainly obtained from marine fish with high ω-3 long-chain unsaturated fatty acids, especially pelagic fish. Fish oil has been widely used in the early food industry. However, with the overfishing of fish, global fishery resources are becoming increasingly scarce, and it has gradually been discovered that there are some problems in obtaining DHA from fish oil: a large amount of persistent organic pollutants accumulate in the bodies of marine fish; DHA from fish oil contains high cholesterol and has a fishy smell, which seriously affects the quality of DHA; fish oil also contains a large amount of other saturated and low-unsaturated fatty acids, which are difficult to concentrate when purifying DHA, resulting in a complex processing process, which in turn increases the production cost of DHA. Therefore, the current extraction and separation of DHA from fish oil cannot meet the requirements of society in terms of quantity and quality. Therefore, finding safer and higher-quality raw materials to extract DHA has received widespread attention from scholars.

The reason why fish contain DHA is that fish eat DHA-rich microalgae and related plankton in the ocean, and their DHA is transmitted through the food chain and accumulated in the fish body. Therefore, research has gradually shifted to extracting DHA from natural microalgae. Using microalgae to produce DHA can not only make up for the shortage of fish oil resources but also compared with traditional fish oil, microbial oils have the advantages of simple fatty acid composition, simple separation and purification process, no fishy smell, suitable for food additives, high utilization rate, easy industrial production and huge health advantages. Schizochytrium is one of the marine fungi and algae rich in DHA. Its biochemical components are mainly lipid proteins and total sugars, of which the fat content can account for 50% of the cell's dry weight and DHA is as high as 20%. 90% of the oil in the cell exists in the form of neutral oils that are easily absorbed by the human triglycerides, and in the form of lecithin which is extremely beneficial to the body. In addition, a large number of active substances useful to the animal body are accumulated in its cells, such as pigments (carotenoids, lutein, astaxanthin,), squalene, etc.

To develop and utilize Schizochytrium on a large scale, a detailed and comprehensive safety evaluation was also conducted. Including subacute toxicity experiments on rats, toxicity experiments on rat development and reproduction, mutagenesis experiments on rats, and safety evaluation on pig development, no toxic side effects were found. This shows that Schizochytrium is safe and reliable to feed animals as an additive, and its safety has also been recognized by the FDA.

Currently, Schizochytrium has become an ideal additive for aquatic and livestock feed. In aquatic and livestock production, adding Schizochytrium has two main purposes: to exert the physiological functions of DHA and Schizochytrium in the animal body to promote the growth and development of the animal, and to use the enrich of DHA in the animal body to develop functional health products rich in DHA.

Promote animal growth and development

In aquaculture, DHA is the most effective essential fatty acid required by fish and crustaceans, but fish and crustaceans cannot synthesize DHA by themselves and can only obtain it from feed. The main purpose of adding microalgae containing DHA to aquaculture is to promote the healthy growth and development of animals. A large number of studies have shown that ensuring the DHA content in feed can improve the endurance of aquatic animals, increase survival rate, and promote their growth and development. At present, the growth effect of adding Schizochytrium has been studied on several aquatic animal species such as sea cucumbers, shrimps, gilthead sea bream, channel catfish, Atlantic salmon, and sea bass. In general, Schizochytrium significantly promotes the growth of aquatic animals and improves feed conversion rate, and the DHA content in the muscles of some aquatic animals has also increased, thereby improving the product quality of aquatic animals. These studies have shown the great potential of Schizochytrium in aquaculture. In addition, schizochytrium can be used to fortify animal aquatic feeds. Some animal feeds used to feed fish and shrimp larvae, such as rotifers, artemia, and cladocerans, lack DHA. However, before feeding, schizochytrium rich in DHA can be used for nutritional fortification to improve the nutritional value of secondary feeds, thereby promoting the growth of fish and shrimp and improving the survival rate.

Adding schizochytrium to the diet of pigs significantly reduces triglycerides in the blood. The DHA content accumulated in the subcutaneous fat of pigs fed with high levels of DHA is more than 13 times higher than that of pigs fed with control levels. Genetic analysis shows that the expression of fat oxidation biomarkers acyl-CoA oxidase 1 (ACOX1), peroxisome proliferator-activated receptor α (PPAR-α), and γ (PPAR-γ) is affected in the subcutaneous fat and liver of pigs. This shows that the DHA-rich schizochytrium fed can play its unique physiological functions in animals, promote the growth and development of animals, and improve the quality of animal products.

Developing new functional products

In recent years, there have been studies on the use of Schizochytrium to produce DHA-rich eggs. At present, with the improvement of living standards, consumers' health awareness is increasing, and foods rich in DHA have become a hot topic for consumers. Poultry products (eggs) contain essential amino acids, fatty acids, vitamins, minerals, and other nutrients required by the human body, and are daily necessities. Compared with expensive health drugs, eggs rich in DHA will be more popular with consumers. Gtadkowski et al. added Schizochytrium powder to quail feed, and the study showed that the DHA content in the egg yolk increased. These studies have shown that adding Schizochytrium to poultry feed can increase the DHA content in the egg yolk, and the DHA deposition efficiency in the egg yolk is related to the DHA content in the feed, different poultry breeds, and different growth stages. Compared with the traditional method of obtaining DHA eggs by adding fish oil or linseed oil to the feed, adding Schizochytrium algae powder has the following advantages: Schizochytrium algae powder can directly increase the DHA content in eggs, and the DHA deposition speed is fast, and the enrichment and stability time is shorter; the unsaturated fatty acids such as DHA in Schizochytrium algae powder are relatively less prone to oxidation because they are hidden in the cell wall.

Schizochytrium algae powder also contains several carotenoids, among which carotene and canthaxanthin are the most abundant. These substances cannot be synthesized in poultry and can only come from feed. As the body continues to ingest these substances, carotenoids are continuously deposited in the yolk, making the yolk color continue to deepen, from light yellow to orange-red, and can be stable in about 1 week, indicating that carotenoids can be transferred to the yolk. This also enhances the quality of eggs. Therefore, adding Schizochytrium to poultry feed to produce DHA eggs has become a trend.

HSF Biotech is a high-tech enterprise in China that focuses on biotechnological innovation and the production of functional health product ingredients. Since its establishment, we have been focused on the differentiation of market applications and the actual demands of customers. Our core business involves natural vitamin E, micro-encapsulation powders, etc.

"Always with the customer" has been HSF's enduring driving force over the years. With its continuous efforts in research and development of microbial fermentation technology over the past decade, HSF owns its strain banks and patented extraction technologies. The launch of the Fermtek^®, a brand for fermentation product line, creates opportunities for us to collaborate with our global partners.

Compare With Traditional Schizochytrium Powder, HSF Has the Following Advantages:

• Originally fermented
• Low-temperature drying
• Chemical solvent-free
• High nutritional value
• Stable product quality
• Whole bacteria with a light smell
• Strong palatability

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