Animal Nutrition-पशुपोषण

Microalgae as feed ingredients for livestock

March 29, 2023

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Microalgae as feed ingredients for livestock

Microalgae are simple microscopic heterotrophic and/or autotrophic photosynthetic organisms that grow in the aquatic environment and can be in unicellular or multicellular structures. Microalgae, which can be found in prokaryotic or eukaryotic structures, can reproduce rapidly and can live even under adverse conditions thanks to their unicellular or simple multicellular structures. It is estimated that there are more than 50000 species of microalgae, but about 30000 species have been identified so far. There are many ingredients in the structure of microalgae, mainly lipids (4-55%), carbohydrates (6-57%), and proteins (10-63%). Some microalgae species have also been reported to contain more than 70% (on dry weight basis) lipids.

Microalgae based Feed is a good source of protein-rich alternative feed for livestock. Compared to meat and eggs, it is a significantly more environmentally friendly source of protein for both people and animals. Although there are many species of algae that might be utilised as feed, several varieties are now widely accessible in the market. Blue-green and green algae are increasingly being added to feed products, and they can be utilised for both animal and human feed. These algae contain a remarkable 40% to 60 % protein content together with a large number of amino acids. Chlorella, Scenedesmus, and Arthrospira are a few examples of the microalgae that can be added in a small quantity (4% or 8%) to traditional feed to improve growth, health, and overall physiology of animals as well as product quality and quantity. They provide a variety of nutritional advantages to animals and will promote their long-term health. Globally, the demand for microalgae in the animal feed industry was US$ 57.54 Mn in 2021. With a 3.5% CAGR for the years 2021 to 2031, the market is anticipated to reach US$ 80.96 Mn by 2031

Microalgae, which generally live autotrophically in nature, perform photosynthesis using their pigments. By performing photosynthesis, they convert carbon dioxide, water and sunlight into biomass. However, depending on the specific characteristics of the species, they can also develop as heterotrophic and mixotrophic, apart from autotrophic conditions. Heterotrophic microalgae use organic carbon as a carbon source in dark conditions. Glucose, galactose, mannose, fructose, sucrose and lactose are commonly used as organic carbon sources in heterotrophic and mixotrophic growth. Bioreactors are used in industrial microalgae production. Microalgae cells are cultured in the laboratory and they are provided to grow and multiply in bioreactor tanks. When the microalgae reach the desired maturity and content values, they are dried by various methods (freeze and spray drying).

Chicken, beef, lamb, salmon and even turkey and legumes, pulses and soybeans are non-vegetarian and vegetarian source of conventional protein in pet foods. These are food of human choice too thus impart food-feed competition. Furthermore, over demand of conventional protein source will increase the feeding cost, may affect expansion of livestock business. These facts extend need to identify alternative protein sources (e.g. insect meals, food waste, agro-industrial byproducts) and other newer proteins. Referring to alternated protein; yeasts, fungi, bacteria and micro-algae, the name Single Cell Protein (SCP) were subjected through fermentation technologies for the protein biomass production at commercial level. There are distinct groups of microalgae, being the eukaryotic diatoms (Bacillariophyceae), green algae (Chlorophyceae) and golden algae (Chrysophyceae) the most abundant in nature. More than 100,000 species have been estimated with a large share of diatoms. Typically, autotrophic microalgae are used for CO2 fixation and to produce organic compounds (biomass) with the sunlight energy and augments oil in a very productive way (Christi, 2007). While, heterotrophic microalgae utilizes organic compound as a source of energy instead of sunlight. Some of them have been successfully cultivated for their specialized nutraceutical values, rich in vitamin A, C and E and Beta-carotene (Pirwitz et al., 2016), astaxanthin (Gouveia et al., 2010). Long‐chain n‐3 PUFA, docosahexaenoic (DHA, 22:6, n‐3) content in Isochrysis galbana is about twice to fish oil. Studies have suggested that autotropic microalgae can modulate milk meat or egg nutritional profile on supplementation in animal diet. Similarly, microalgae are increasingly being used in pet food to improve palatability and meet the requirements for natural ingredients in pet food formulations. A microalga also has a longer shelf life and is available in powder and liquid forms, making it simple to compounding. The nutritional properties of spirulina microalgae are propelling the global market for pet food. According to a report (https://www.futuremarketinsights. com) only Spirulina was expected to account for more than 64% of the market in 2021.

Chemical composition of micro-algae

Chemical composition of different algae have studied in many previous studies and general overview on the major constituents, selected data of various micro-algal species are presented in Table 1 (Yaakob et al., 2014). Microalgae composed of proteins, carbohydrates, lipids, vitamins, minerals, and bioactive substances like carotenoids and other macro and micro nutrients. Microalges biomass contains all essential nutrients to replace artificial supplement with natural sources. Specifically, one of the primary criteria favoring their use in feed production is the high protein content of several microalgae species (Kovac et al., 2013). The majority of microalgae protein fractions have an average quality that is comparable to or even superior to that of traditional plant protein fractions (Becker, 2004). In terms of quality, dry chlorella is comparable to yeast, soy flour, and milk protein, with a protein concentration of between 50 to 60 % (Kovac et al., 2013) and Arthrospira microalgae about 60 to 70 % on dry weight with all the essential amino acids (Gutiérrez-Salmeán et al., 2015) but low in methionine and cysteine content. The amino acid profile of selected microalgae have been compared under studies with recommended balanced protein source (FAO/WHO, 1973), it has been found that the amino acid profile of algal protein was below to egg white protein but better than the any vegetarian protein, including soybean protein (Morales de León et al., 2005). Carbohydrates are also important nutrients in microalgae. Indeed, microalgae cell wall typically comprise of hemicellulose (Gutiérrez-Salmeán et al., 2015), which may be beneficial to animals’ gut. In the case of Arthrospira, there is an efficient digestion of its carbohydrate fraction by ruminants when used in levels up to 20% of total feed intake, compared to other algal feed types, like Chlorella or Scenedesmus obliquus (Gouveia et al., 2010). Microalgae are a rich in minerals and vitamins (Christaki et al., 2011), specially, Green algae (such as Chlorella) are good source of cobalamin (vitamin B12). Aurantiochytrium are used as an excellent source of carotenoids to astaxanthin (Aki et al., 2003).

Applications of microalgae in feed Animal

feed industry consumes more than 30% of global microalgae production (Becker, 2004) particularly, Schizochytrium sp., Chlorella sp., Arthrospirasp., Isochrysis sp. and Porphyridium sp. Arthrospira. Studies have shown that microalgae inclusion in animal diets can improve growth and meat quality in ruminants, pigs, poultry, and rabbits. However, results are highly dependent on the composition of microalgae and their amount in the diet. Schizochytrium sp. improves fatty acid composition in pork and poultry meat, owing primarily to its high docosahexaenoic acid content (DHA). Vegetable‐protein sources which contain rich α‐linolenic acid (C18:3n‐3) as a precursor for the n‐3 LC‐PUFA, DHA and EPA source are limited in numbers, like linseed and sunflower oil seed. Microalgae such as the genus Schizochytrium have been used as potential source of omega 3‐PUFA and high DHA concentration (approximately 20%) sources used in dog food. Other species of Phaeodactylum tricornutum and Nannochloropsis sp. (autotrophic) rich in EPA 39% of total FA (Adarme-Veja et al., 2012) used in animals feeds. Additionally, they also carries anti‐inflammatory properties, alter skeletal muscle function, improve reproductive status of animals, skin and appendage health. Souza (2018) reported that DHA-rich algae at 0.4% inclusion level in dry pet food resulted in higher protein digestibility and palatability in dogs. Further, the Spirulina platensis as whole dried powder is beneficial when used at 10.7% of pet food on DM basis (Zhang et al., 2001). Menezes Souza et al. (2019) reported palatability, growth performance, health status, oxidative stability of dog food improved on micro algae supplementation. DHA- PUFA enriched composition of microalgae can improve growth performance, supports the immune functions, inflammatory modulators eicosanoids (prostaglandins, leukotrienes, thromboxanes, and prostacyclins) with less inflammatory action, resolvins, and protectins, which reduce inflammation (Calder, 2012) admires disease resistance, antiviral and antibacterial action, gut function and probiotic colonization stimulation. DHA directly regulates inflammatory function through gut associated immune organs. Higher concentration of beta‐carotene, vitamin E, sterols, phenolics and flavonoids imparts oxidative stability, increase nutrient digestibility and higher metabolisable energy intake. However, studies have reported variable response of microalgae cell wall composition on growth performance in monogastric and ruminants, microalgae cell walls contain cellulosic material can be differentially fed to ruminants, while it is necessary to process algal as biomass before appropriate in monogastrics animals diet (Becker, 2004). Furthermore, the use of carbohydrate-active enzymes with micro algal protein will significantly improve the efficiency of nutrient utilization in monogastric animals. In conclusions, microalgae can be used as alternate feed ingredients staple food crops such as corn and soybean, mitigating current competition with the human food chain and contributing to agricultural sustainability. Inclusion of microalgae in pet food can be an option for the pet owner seeking palatable vegetarian diet enriched n-3 LCPUFA alternative to fish oil of best oxidative stability. Nutritional composition of microalgae can improve growth performance, health status, immune function and feed quality supplements of will in pet food will support.

DIFFERENCES BETWEEN MACROALGAE AND MICROALGAE
Macroalgae are large aquatic photosynthetic plant-like organisms that are visible to the naked eye. They are often referred to as seaweeds. Whereas microalgae are small aquatic photosynthetic plant-like organisms that can only be seen under a microscope. They are often called phytoplankton. Thus, this is the main difference between macroalgae and microalgae. Besides this, another important difference between macroalgae and microalgae is that macroalgae are multicellular whereas microalgae are unicellular.

ALGAE AS A VALUABLE INGREDIENT
Problems such as food insufficiency and unbalanced nutrition that may be encountered with the increasing population push human beings to find alternative sources. In this context, algae attract attention with their high nutritional content and health benefits, as well as providing a sustainable food supply. And with these features, algae are also considered a candidate to be a functional food. Daily consumption of foods with the addition of functional ingredients produced by algae can improve health and reduce the risk of chronic diseases. Algae, which have been considered as food for centuries in Asian countries, have now been used in almost every region of the world, either directly as food, as a food additive or as a food supplement.

Similar developments are valid within the livestock sector. The feed raw materials used cannot meet the demand due to population growth, and their costs are increasing day by day due to climatic, ecological, logistical reasons. It is seen that global warming, wars, global crises and pandemic also contribute to these cost increases.

SUSTAINABLE PRODUCTION: FROM WASTE MATERIALS TO VALUABLE FOOD…
One of the main elements that make algae popular today is its compliance with the sustainable production model. Algae use waste materials as an energy source, converting them into valuable nutritional ingredients such as omega-3 fatty acids. Therefore, algae are one of the most important producers of the food chain. It seems possible for algae to be an important source in meeting the nutritional needs in the future, due to the fact that they can increase their weight 2-3 times in a day, their production is easy and economical, and there are no side effects. Metabolites such as fat and fatty acids, protein, carbohydrates (sugars), pigments, minerals, vitamins, sterols, antioxidants and bioactive polyphenols can be produced from algae, which show a very rapid increase in biomass due to their division and proliferation.

USAGE AREAS OF ALGAE
Algae have been used for various purposes in many areas from past to present. Algae are among the important resources used in many fields such as the food industry, medicine, pharmacy, agriculture, animal nutrition, waste treatment, cosmetics, and biodiesel production. Algae contain many bioactive molecules with wide biological activities such as antioxidant, antibacterial, antiviral and anticarcinogenic. Phycocolloids, which are used as active and auxiliary substances in pharmacy, are obtained from algae. In addition, antioxidant compounds contained in algae have an important place in the fight against free radicals, which are formed during the functioning of metabolism and are the initiator of some chronic diseases.

ALGAE AS AN ALTERNATIVE INGREDIENT IN ANIMAL NUTRITION
Nutrition plays an important role in the regulation of growth, development and physiological functions as well as being necessary for the maintenance of life. Depending on these factors in both human and animal nutrition, the demand for healthier and natural products is increasing day by day. In addition, the increasing world population, the decrease in agricultural resources and the variability of economic conditions have led to studies for the production of easy-growing, high quality and natural alternative additives. There is a reliable consumption of algae, one of the natural alternative additives, from the past to the present. These natural foods, which are sources of protein, vitamins and minerals, play an important role in both human and animal nutrition. Thanks to the studies carried out in recent years, special structures such as phycocyanin and polysaccharide in the content of algae attract attention. In addition to its growth and immune effects, it has been reported that algae also have productivity-enhancing properties in animal products such as meat, milk and eggs in the field of livestock. In addition, the use of algae in the fields of animal feed utilization and fertility improvement has also been demonstrated by studies.