In intensive fish farming, the stress caused by high-density rearing can reduce the disease resistance of the fish, induce disease, and even outbreaks of disease. According to incomplete statistics, the average annual loss of aquaculture diseases in my country has reached tens of billions, of which fish accounted for 55% to 77%, and shrimps and crabs accounted for 11% to 28%. Enhancing the immunity of aquatic animals by means of nutrition has become a key issue in the field of healthy breeding.
Functional oligosaccharides have the characteristics of not being degraded by animal endogenous enzymes, not being absorbed, no pollution, no residue, high stability, good compatibility with other additives, etc., and can withstand high temperature processing of feed pelleting while maintaining its structure and function Because of its completeness, it has received high attention from people, and many countries in the world have approved it as a feed additive. Chitooligosaccharide is one of the functional oligosaccharides approved by the Ministry of Agriculture for use in feed.
Studies have shown that adding an appropriate level of Chitooligosaccharide to fish feed can significantly promote fish growth and improve feed utilization efficiency. Cai Shengchang’s research shows that adding 1.0% Chitooligosaccharide can increase the specific growth rate of turbot juveniles by 9.2%, increase the weight gain rate by 15.55%, increase protein efficiency by 16.82%, and reduce feed coefficient by 17.78%.
Sun Liwei’s research shows that adding 0.50% Chitooligosaccharide to feed can significantly increase the weight gain and specific growth rate of juvenile tilapia, and reduce the feed coefficient. Liu Hanliang and other studies found that 200 mg/kg Chitooligosaccharide can significantly increase the growth rate and weight gain of rainbow trout, and significantly reduce the feed coefficient. Changqing and other studies have shown that 0.5% and 1% Chitooligosaccharide can promote the growth of sea bass.
The growth-promoting mechanism of oligosaccharides on fish has not yet been fully elucidated. At present, the following are mainly recognized:
(1) Promote the growth of beneficial bacteria, inhibit the colonization and proliferation of harmful bacteria, and maintain the microecological balance of the digestive tract. The microbial flora of the fish digestive tract is composed of aerobic bacteria, facultative anaerobes and absolute anaerobes, and changes continuously with age, nutritional status and growth environment, and is closely related to fish growth and health. Chitooligosaccharides can be used by beneficial bacteria in the intestines, promote the proliferation of beneficial bacteria, inhibit the colonization and growth of harmful bacteria, and regulate the intestinal microecological balance, thereby promoting the healthy growth of animals.
(2) Activate the fish body's immune system, enhance the body's immunity and anti-stress ability. Phagocytes in animals can swallow foreign bodies that enter the body. Phagocytes can digest pathogenic organisms while retaining relevant antigen information and passing it to relevant lymphocytes, thereby stimulating the body's humoral and cellular immunity. Lysozyme (LZM) is an alkaline lysis enzyme secreted by lymphocytes. It mainly acts on Gram-positive bacteria and certain specific bacteria. It dissolves the mucopolysaccharides in the bacterial cell wall, resulting in damage to the cell wall and cell content. The substance is forced to be released outside the cell, eventually dissolving and disappearing the bacteria. Therefore, the phagocytic ability of phagocytes and LZM activity are important indicators that reflect the non-specific immunity of fish. Chitooligosaccharides, as a functional oligosaccharide, can significantly enhance the activity of serum lysozyme, thereby effectively resisting infection by pathogenic microorganisms.
(3) Improve the structure of fish intestines, improve the integrity of the intestinal mucosa and the activity of digestive enzymes, and increase the digestibility of feed. The integrity of fish digestive tract mucosa, the height and density of intestinal villi, and the activity of digestive enzymes are obviously related to the digestibility of nutrients. Chitooligosaccharides can increase the length, height and density of the intestinal villi of juvenile tilapia, significantly reduce the thickness of the juvenile intestinal wall, and significantly improve the digestibility of dry matter and crude protein.
(4) Improve lipid metabolism and increase antioxidant capacity. Studies by Choi et al. have shown that Chitooligosaccharides, as a product of acid hydrolysis or enzymatic hydrolysis of chitosan, has the effect of lowering blood lipids. The possible reason is that Chitooligosaccharides can be electrostatically combined with bile salts to hinder the reabsorption of bile salts through the enterohepatic circulation, and promote the conversion of cholesterol into bile salts, thereby reducing the cholesterol content. Chitooligosaccharides can also be combined with fat electrostatically to form polymers, which prevents bile salts from accumulating to form micelles and inhibits the formation of fat droplets, thereby reducing the digestion and absorption of fat.
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JUNE JIANG/SALES MANAGER
Qingdao HEHAI Biotech Co.,Ltd.
Tel: 13045058792
Fax:+86-532-81926219
E-mail: june@marine-oligo.com
Address: Room 806, D&D Fortune Center, No.182-6, Haier Road, Qingdao,China