The increasing demand for organic animal products and the emergence of the problem of antibiotic resistance have prompted scientists to look for unconventional ways to improve the performance of farm animals while maintaining the health of humans, animals and the environment. Therefore, in modern livestock and poultry production systems, various feed additives are devised to maintain the health and metabolic status and greatly improve the productive and reproductive performance of farm animals. Food additives of natural origin, including probiotics, prebiotics, organic acids, feed enzymes, have been used as antibiotic alternatives.
One of the new and low consumption feed additives is chitosan. Chitosan is obtained from chitin (part of the exoskeleton of shrimps, crabs and insects). Chitin is an abundant natural mucopolysaccharide with white, hard, inelastic and nitrogenous compounds. Chitosan is a byproduct of the fishing industry. It is also found in the cell wall of some fungi and bacteria. And in terms of abundance, chitosan is the second most abundant natural biopolymer after cellulose. It can be obtained by deacetylating chitin, which is isolated from the shells of crustaceans (crabs and shrimps) as well as the exoskeletons of insects and the cell walls of fungi. Structurally, chitosan consists of N-acetyl-2- Amino-2-D-glucopyranose and 2-amino-2-deoxy D-glucopyranose are linked by β-(1-4) glycosidic bonds. Chitosan derived from whole crab shell is more soluble than crab legs. However, low molecular weight chitosan provides antibacterial properties and good solubility when combined with liquid or solid food. Chitosan with a high degree of deacetylation increases biological functions.
Meanwhile, chitosan oligosaccharide (COS) is a chitosan oligomer that is widely used in the livestock industry as feed supplements to improve productivity and intestinal function. COS are derived from the enzymatic and chemical hydrolysis of chitosan, and they are non-toxic linear polysaccharides with a low degree of polymerization. They have lower molecular weight, lower viscosity, higher solubility in water and higher bioactivity than chitosan. The excellent properties of these polysaccharides, such as biocompatibility, biodegradability, bioactivity, bioabsorption, non-toxicity, and good absorption properties, make them very suitable and necessary biological materials and attract a large amount of industries, including animal feed. he does.
Chemically, unlike chitin, chitosan contains hydroxyl groups. Therefore, chitosan has antimicrobial, anti-inflammatory, antioxidant, anti-tumor properties, immune stimulant, blood cholesterol lowering, intestinal protector.
In livestock production, feed additives are commonly used to improve animal health and productivity. Various ingredients are combined during feed formulation with the ultimate goal of producing nutritious diets that improve productivity, metabolism, health and welfare.
Chitosan, when incorporated as a feed additive, shows significant nutritional potential. Therefore, chitosan-containing feed formulations and related composites have rapidly gained importance in animal nutrition.
Use of chitosan for growing animals
For growing animals, strengthening the function of the digestive system and maintaining their general health status are the key factors that control the growth performance of these animals in the early stages of development.
Chitosan is a suitable feed additive for growing animals because it can increase the release of digestive enzymes from the stomach, pancreas and intestinal mucosa. In addition, chitosan can improve the digestibility of intestinal contents, increase absorption capacity, and promote cell division, which means that chitosan may be used as a dietary supplement to improve digestion efficiency and stimulate nutrient absorption in pigs. Used milk. Chitosan also reduces intestinal morphology, villus structure and microbiota, food digestion and absorption, and diarrhea in poultry, weanling pigs, and rabbits, respectively. It is interesting to note that the positive effects of chitosan on the functioning of the digestive system have been confirmed in ruminants whose rumen plays a major role in their growth and health. Chitosan has positive effects on rumen fermentation and fiber digestibility in beef calves and improves rumen fermentation products by increasing propionic acid synthesis compared to methane synthesis. Several studies have confirmed the positive effects of dietary chitosan supplementation in various farm animals. Chitosan improved the growth performance of growing guinea pigs, rabbits, lambs, calves and quails.
Researchers reported that dietary chitosan supplementation improved health conditions and prevented diarrhea in growing animals. In addition, chitosan supplementation can improve intestinal morphology and improve villus structure, microflora, intestinal nutrient digestibility, and microbial protein synthesis in ruminants and monogastrics. However, it is important to emphasize that the effects of chitosan on animal health and growth performance depend on the dose and molecular weight (MW) of chitosan.
Benefits of chitosan for adult animals
Chitosan is not only beneficial for growing animals, but also has positive effects on adult animals. Adding chitosan to the diet of adult farm animals can improve many reproductive events such as pregnancy and its outcomes, milk and egg production, and To support production in dairy cows, pigs and laying hens. The improvement of reproductive performance is related to the ability of chitosan. Chitosan improves the tissue structure and function of gonads and the synthesis of sex hormones and minimizes the negative consequences of various types of stress, such as oxidative stress. Chitosan can be an ideal environment for growth and survival. By increasing the immunity and antioxidant capacity of the fetus, the function of the placenta and the use of nutrients by the mother or children can be improved.
It has been proven that chitosan and its derivatives have a beneficial biological function in changing the intestinal flora. Due to its antibacterial properties, chitosan has recently been used as a silage inoculum and as a rumen modifier in beef and dairy cattle with promising results.
The effects of chitosan supplementation on neutral detergent fiber, acid detergent fiber and dry matter digestibility were studied in beef heifers fed with high forage diet. When comparing the effects of chitosan on laboratory cultures, the researchers found that chitosan-containing groups produced more total volatile fatty acid synthesis than monensin-containing groups. In addition, they found that chitosan changes the fermentation pattern from acetate synthesis to propionate in rumen simulation studies. Chitosan can also improve milk production and quality.
Studies show their beneficial effects in improving growth performance, increasing productivity, immunological responses and suppressing intestinal microbial pathogens. Interestingly, chitosan and chitosan-based materials have been widely used as potent antimicrobial agents against a wide range of microbes. Chitosan-supplemented diets are a suitable alternative to antibiotics, along with significant improvement of intestinal function. These results are directly related to their physicochemical properties such as low toxicity, availability, biocompatibility, biodegradability, mucosal adhesion, increased permeability, non-antigenicity and relatively low cost of production from natural sources.
In addition, their drug delivery properties are also well established, which are used as carriers for efficient loading, targeted delivery, and controlled release of active substances to the target organ. Some studies have shown that chitosan, as a food supplement in animal feed, improves digestive system ulcers by absorbing accumulated toxins and treating chronic constipation.
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