In recent years, the research of plant extracts and their applications have become one of the hot spots in multiple fields such as agricultural science and biology, and have potential applications in the feed industry. This paper reviews the types and structures of natural feed additives, their mechanisms of action and their potential applications in pet growth and health care.
A. Types and main components of natural feed additives
The properties of natural plant extract feed additives determine the scope of their application in feed. According to relevant reports, more than 1,000 types of Chinese herbal medicines have been used in veterinary medicine, and about 500 of them are used in feed additives. However, there is no very precise definition of the classification of natural plant-derived feed additives in the industry. According to the role and efficacy of additives can be divided into immune enhancement, disease prevention and health care, growth regulation, microecological regulation, food induction, and hair beautification.
B. Antibacterial effect of natural additives
With the improvement of modern chemical separation technology, the effective antibacterial active ingredients of plant extracts are increasingly isolated. Among them, the main antibacterial components contain flavonoids, alkaloids, volatile oils, polysaccharides, anthracenes, organic acids, saponins and other compounds. Its mechanism of action is more complex, mainly through changing the integrity of biological membranes, affecting the synthesis of protein nucleic acids, inhibiting the activity of enzymes in the body of the germ, changing the permeability of cellular ion channels, and improving the immune effect of the body to play the role of antibacterial. Natural has become a trend in the marketing of pet food, plants from natural materials, compared with antibiotics have a safe, non-resistant characteristics, and gradually become an emerging feed additives.
C. The growth-promoting effect of natural additives
A large number of studies have proven that plants contain different levels of organic complexes, generally containing a variety of nutrients such as amino acids, vitamins and minerals. These nutritional elements are good to supplement the shortage of material elements in the diet of pets and meet the nutritional needs of the organism. After a large number of experiments to verify that certain elements in herbal medicine not only have a certain nutritional value, but also have the effect of regulating the metabolism of the organism.
Yu Wenhui et al. showed that plant extracts can significantly increase the content of leukocytes, erythrocytes, lymphocytes and hemoglobin in the blood of dogs, reduce serum fat content, increase the daily weight gain, daily feed intake and food utilization rate of dogs, promote the absorption of small intestine and facilitate digestion. Some weanling puppies have imperfect digestive function and low disease resistance. Yan Zeqing et al. conducted experiments using some Chinese herbal medicines to improve digestion and enhance immunity, and the results showed that natural feed additives have certain promotion and enhancement effects on the growth performance of puppies. Some herbal medicines contain a variety of enzymes and substances that enhance enzyme activity.
Xia Xiaodong et al. added 2% plus-flavored Sijunzi Tang to the diet could significantly increase the content of amylase, lipase and protease in the pancreas and D-xylose in the serum of dogs, and enhance the digestive and absorption functions of dogs. Natural active substances such as green tea powder, bifidus factor and probiotics can regulate the intestinal flora of canine organism and play the role of antibacterial and improve the intestinal health. Shu Yingshang et al. showed that adding Astragalus polysaccharide in dog food can significantly increase the levels of IgA, IgG, IgM and IFN-Y in dog serum and promote the expression levels of IgA mRNA and SIgA protein in dog small intestinal mucosa, thus enhancing the intestinal mucosal immune function of dogs.
D. Natural additives to enhance the immunity of pets
Plant extract feed additives contain alkaloids, polysaccharides, organic acids and other biologically active substances, which can be involved in regulating various physiological functions. For example, Huang Lian, Astragalus, green tea, etc. contain bioactive polysaccharides, which can stimulate the immune cells such as macrophages and T-lymphocytes in animals, and then promote the production of relevant cytokines, promote their proliferation and differentiation to produce tumor necrosis factor, interleukin-2 and other cytokines, thereby regulating the immune response of the animal body. Honeysuckle, hawthorn and citrus contain organic acids, which can lower the pH of digestive matter and increase pancreatic secretion and other functions.
Yan Zeqing et al. significantly increased the lymphocyte conversion rate and serum levels of lgG, IgM and lysozyme by using health dog food containing Chinese herbs, and the results showed that natural additives can improve the immunity of older dogs. The study of Lou Hongjun et al. proved that the use of dog food containing herbal additives could reduce the concentration of adrenocorticotropic hormone, cortisol and interleukin-2 in the serum of dogs to a certain extent.
E. Natural additives for the prevention and control of pet diseases
Traditional plant extracts with natural and safe medicinal ingredients, in addition to improving the immunity of the pet organism and the ability to resist external evil, but also anti-viral as well as anti-stress, the prevention and control of viral diseases such as canine distemper and canine microcephaly. In recent years, the application of Chinese medicine in the prevention and treatment of pet diseases has achieved very good results. The health food containing herbs can promote the treatment or inhibit the onset of disease by strengthening the spleen and kidneys, while taking into account the nutritional and health needs of pets.
