Mechanism of fermented feed and its application in poultry production
With the complete ban on feed antibiotics, the development of feed antimicrobial alternative products and technologies has become an urgent need and research hotspot for farmers. Fermented feed has the characteristics of improving the body's immunity and disease prevention ability, and has become an important part of many needs and research hotspots. Fermented feed refers to the feed produced by microbial fermentation of single feed or mixed feed allowed to be used according to relevant national regulations. The use of fermented feed in poultry production can effectively improve the microecological balance of poultry digestive tract, enhance immunity, improve growth performance. In this study, the mechanism of action of fermented feed and its application in poultry production were reviewed, in order to provide a reference for the popularization and application of fermented feed in poultry production.
Table 1 Related fermentation services at BOC Sciences.
Mechanism of action of fermented feed
Improves intestinal microbial balance
The microorganisms in the digestive tract of animals play an important role in regulating the digestion, metabolism and immunity of nutrients in the body, promoting intestinal secretion and signal transmission, especially the beneficial microorganisms that colonize the intestinal mucosa. Under normal circumstances, the existence of various microbial populations in the animal intestine maintains a dynamic balance, when the body is affected by certain stress factors, this microecological balance may be destroyed, resulting in the imbalance between the various microbial flora in the intestine, once the balance between these microbial communities is lost, it will make the dominant flora replace, some aerobic bacteria or facultative anaerobic bacteria such as Escherichia coli, Salmonella, etc. increase in large quantities, become the dominant flora, break the microecological balance of the intestine, and cause the disorder of the body's digestive function. With the continuous supplementation of probiotics, probiotics gradually colonize in the intestine and become the dominant flora, which restricts the adhesion and growth of pathogenic bacteria in the intestinal mucosal epithelial cells through competitive inhibition and the production of anti-adhesion substances, so that beneficial bacteria become the dominant bacteria and protect the health of the host. At the same time, the probiotics entering the intestine will quickly consume the oxygen in the intestine, and secrete metabolites such as lactic acid to reduce the pH of the intestine, so that the intestine forms an acidic anaerobic environment, which is not conducive to the growth and proliferation of pathogenic bacteria, thereby improving the microecological environment of the gastrointestinal tract of animals and improving the immune function of the body. The beneficial flora produces some polypeptides such as lysozyme and bacteriocin, which can effectively inhibit the growth of harmful bacteria and further maintain the microecological balance of the intestinal flora of the host animal. In addition, after biological fermentation of feed raw materials, macromolecular proteins are degraded into small peptide substances, and some small peptide substances have strong antioxidant function, which can protect the host immune system and avoid the loss of excessive free radicals in the body. At the same time, probiotics such as yeast, lactobacillus, and bacillus in fermented feed can also be immune activated through their metabolism of bacteriostats and other substances, stimulate the growth and development of intestinal immune organs, enhance the ability of B cells to produce antibodies, stimulate the body's humoral immunity and cellular immunity, and enhance the body's immunity and disease resistance. For example, butyric acid in short-chain fatty acids produced by microbial fermentation in feed can induce the secretion of MUC2 in goblet cells and the differentiation of T cells, and at the same time inhibit the expression of nuclear factor-κB, thereby improving the immune function of animals.
Promote the digestion and absorption
Feed through fermentation produces a large amount of organic acids, which have a sour flavor, which can stimulate poultry feeding, increase feed intake, and then improve feed utilization. Through the metabolic activities of microorganisms, fermented feed converts feed protein into microbial bacterial protein, bioactive small peptides, amino acids, and microbial active probiotics, producing a large number of metabolites such as organic acids and enzymes, and at the same time decomposing macromolecular substances such as cellulose and protein into small molecules that are easy to be digested and utilized by animals, so as to improve the digestion and utilization rate of nutrients in feed. The feed that enters the poultry body contains anti-nutritional factors that are difficult to be degraded, such as α-galactoside, non-starch polysaccharides, phytic acid, tannins, cyclo propylene fatty acids, thicolates, etc., as well as toxins that affect the digestive function, immune function and production performance of poultry and even life-threatening, such as aflatoxins produced by mildew, free gossypol remaining in cottonseed meal, etc., probiotics in fermented feed can degrade these macromolecular anti-nutritional factors and toxins, thereby improving feed quality. Qiu used Lactobacillus plantarum and Aspergillus niger to carry out solid-state fermentation of common rapeseed meal, and the results showed that the crude protein content of rapeseed meal increased by 6.57%, the small peptide content increased by 88.76%, and the crude fiber content decreased by 11.31%. The anti-nutritional factors isothiocyanate decreased by 64.00%, oxazolidinthione decreased by 84.82%, and glucosinolate decreased by 75.16%. The total amino acid content increased by 11.59%. Zhang Yu used Bacillus subtilis BS12 to ferment corn-soybean meal feed, and found that the soybean globulin in soybean was degraded by 87.40%, and the degradation rate of β-coglobulin was 76.60%. Bacillus subtilis BS12 and Enterococcus faecalis were used for mixed fermentation, and when the ratio of the two was 8:1 (mass ratio), the content of soybean globulin was reduced to 8.31 mg/g, and the content of β-coglobulin was reduced to 6.44 mg/g.
Animal digestion and utilization of nutrients is mainly through the action of digestive enzymes in the digestive tract, the higher the activity of intestinal digestive enzymes, the more conducive to the digestion and absorption of nutrients such as crude protein and crude fat in feed. The organic acids, active bacterial proteins, folic acid, active oligopeptides and growth-promoting factors produced during the fermentation process of feed can improve the intestinal microecological environment and stimulate the secretion of endogenous digestive enzymes such as protease, amylase and lipase. Studies have shown that fermented feed can increase the activity of intestinal digestive enzymes in poultry. At the same time, the non-starch polysaccharide hydrolase produced by fermentation can reduce the viscosity of the digested contents in the small intestine and improve the activity of digestive enzymes. Various organic acids such as lactic acid and acetic acid secreted by beneficial bacteria such as lactic acid bacteria in microbial fermented feed can reduce intestinal pH and improve the absorption of minerals such as calcium, phosphorus, iron, zinc and vitamin D in the animal intestine, thereby improving the quality of livestock and poultry products. Probiotics and their metabolites can reduce cholesterol in the body, and can also hydrolyze bile salts, co-precipitate with cholesterol, affect the expression of cholesterol absorption-related transporter genes, and then regulate the lipid metabolism function of laying hens.
Other roles
Fermented feed is rich in lactobacilli and bifidobacteria, which can affect the metabolism of the host, especially the liver and intestinal tissues of the host, improve the activity of antioxidant enzymes such as superoxide dismutase and glutathione peroxidase, reduce the oxidative stress response of the body, and thus improve the quality of livestock and poultry products. Fermented feed regulates intestinal flora, maintains intestinal health, improves feed nutrient utilization, reduces the content of residual protein in the hindgut segment and the abundance of decomposition related flora, and then reduces harmful metabolites such as indole, histamine, hydrogen sulfide, and skatin produced by fermentation of intestinal residual protein by posterior intestinal microorganisms, reduces the concentration of harmful gases in livestock houses, and reduces poultry respiratory tract and eye diseases.
Application of fermented feed
In broiler production
Luo's research found that fermented feed can effectively increase the average daily weight gain of Wenchang chickens during the fattening period, improve the diversity of their intestinal flora. Wei Bingdong's study showed that adding 5% and 10% fermented corn gluten meal to broiler diet significantly reduced the feed-to-weight ratio, improved its growth performance, adjusted its intestinal microbiota structure, and increased the activity of antioxidant enzymes in its serum. Feng's study showed that the addition of 5% fermented wheat bran to the diet to partially replace corn could improve the activity of duodenal digestive enzymes and the abundance of intestinal microbiota in broilers. Ye Chengzhi's research showed that adding 2.5% fermented feed to the diet could improve the production performance of broilers, and significantly increase the daily feed intake and daily weight gain of 1~21-day-old and 1~42-day-old broilers. It can significantly reduce cooking loss and shear force, increase the content of myosylate in the chest, improve the composition of amino acids, fatty acids and volatile flavor compounds, improve the physicochemical properties and flavor of muscle, and the addition amount of 5.0% has a good improvement effect. Chen found that fermented feed can improve the quality of broiler chicken in the experiment of fermented rapeseed meal. In summary, fermented feed can improve the balance of intestinal flora in broilers, improve their growth performance, and improve the quality of chicken.
In layer production
Production performance and egg quality are the main economic indicators of layer breeding. Li replaced the diet of laying hens with 25% and 50% EM fermented feed, and the egg production rate increased by 7.13% and 8.16% respectively, and the feed-egg ratio decreased by 13.18% and 11.63% respectively, and the difference was extremely significant. Studies by Engberg and Ko⁃thari have shown that adding fermented feed to the diet of laying hens can significantly improve the laying performance of laying hens and improve egg quality, such as egg yolk, eggshell color, eggshell breaking strength and yolk antioxidant capacity. Zhu's research shows that adding lactic acid bacteria fermented feed to the diet of laying hens can improve the egg production rate and protein Hastelloy units, reduce the feed-to-egg ratio, and improve economic benefits, and it is appropriate to replace the compound feed of laying hens with a ratio of 15%. Kang's study found that adding 10g/kg of lactic acid bacteria fermented sea buckthorn to the diet of Hailan brown-shell laying hens could significantly increase the daily egg production and egg weight of laying hens, increase the number of intestinal lactic acid bacteria, and reduce the number of E. coli. Wang Yamin studied the effects of probiotic fermented feed on the production performance, egg quality and lipid metabolism of laying hens, and found that adding probiotic fermented feed to the diet can improve the egg production rate and average egg weight of laying hens, and reduce the content of cholesterol, triglycerides and serum cholesterol in egg yolk. In summary, fermented feed can improve the production performance of laying hens and the quality of eggs, and improve breeding efficiency.
In broiler ducks production
Luo's research has shown that adding lactic acid bacteria and Bacillus subtilis for fermentation on the basis of using full-price compound feed can promote weight gain, improve feed remuneration and reduce mortality in broiler ducks. Li Ning's research has shown that adding 2.5% and 5% fermented feed to the full price compound feed can maintain the balance of intestinal flora of meat ducks, enhance the immunity of meat ducks, increase the slaughter rate, reduce the amount of pesticides, reduce the nutrient residues in the feces and the ammonia content in the air, and reduce the stimulation of the respiratory tract and body surface of the meat ducks, which not only increases the breeding efficiency, but also protects the environment. The improvement effect of adding 5% fermented feed on the intestinal flora of broiler ducks was significantly better than that of adding 2.5% fermented feed. Yin fed 1-day-old Cherry Valley broiler ducks with 0.1% mixed bacterial baking powder with lactic acid bacteria and bacillus 1:1 (mass ratio), and found that the weight of the broiler ducks at 35 days of age was significantly higher than that of the control group (basal diet). The serum total protein and albumin indexes, thymus index, spleen index and bursal index of broiler ducks were significantly increased. The number of Lactobacillus ileum, Bifidobacterium, Enterococci and total anaerobic bacteria in ducks increased significantly, while the number of Escherichia coli and total aerobic bacteria decreased significantly. The results of Zhang Aijia's study showed that the addition of 2.5% and 5% bran-corn-soybean meal mixed fermented feed significantly increased the redness value of the pectoral muscle of the broiler duck 45min after slaughter, and the addition of 2.5% mixed fermented feed significantly increased the cross-sectional area of the pectoral muscle fiber of the broiler duck, but significantly reduced the protein expression of MyHC-I, and the addition of 7.5% mixed fermented feed to the diet significantly increased the triglyceride level in the pectoral muscle. In addition, the expression of FASN protein in all experimental groups supplemented with mixed fermented diet increased significantly, and the protein level of PNPLA2 in the pectoral muscle supplemented with 5% and 7.5% fermented diet also increased significantly. In summary, fermented feed can improve the growth performance, immune function, slaughter performance and meat quality of meat ducks.
In laying ducks production
Ruan Dong studied the effects of fermented feed on egg laying performance, egg quality, intestinal digestive enzyme activity and immune function of laying ducks, and the results showed that the addition of 2% and 4% fermented distiller's grains significantly increased the daily egg weight and jejunal chymotrypsin and trypsin activities of laying ducks. The addition of 4% fermented distiller's grains to the diet significantly reduced the feed-egg ratio, and significantly increased the egg white weight, egg yolk color, relative mRNA expression levels of jejunal mucin, secretory immunoglobulin A (SIgA) and SIgA content in laying ducks. The addition of 4% fermented mixed feed and 4% fermented distiller's grains significantly reduced the pH of the muscle, stomach and glandular stomach of laying ducks. The addition of 4% fermented mixed feed significantly increased the activities of jejunal lipase and chymotrypsin in laying ducks. The results showed that fermented distiller's grains had a better effect on egg laying performance, egg quality, intestinal digestive enzyme activity and immune function than fermented mixed feed, and the addition level of 4% was better. The addition of fermentation products of by-products extracted by traditional Chinese medicine to the feed can improve the egg production level of Jin ding ducks. Sandi's research found that fermented feed had a certain effect on Pegagan's egg index, yolk score, eggshell thickness, egg uniformity and cleanliness, and the higher the level of full feed on the basis of fermentation, the higher the egg yolk index and yolk score, and the smaller the eggshell thickness. The above studies have shown that fermented feed can improve the production performance of laying ducks and improve the quality of eggs.
In other poultry production
Huang Xiaoyun's research found that adding 5% of the active microbial fermented feed to the pigeon diet can significantly increase the average daily weight gain of the pigeon, reduce the feed-weight ratio, and improve the group uniformity and health status. Hui found that feeding fermented feed can maintain the intestinal health of quails, regulate the balance of microflora, improve their internal environment, increase egg weight, improve egg quality and reduce the cholesterol content of egg yolk. Niu's research found that the fermented mixed feed of Bacillus, yeast and lactic acid bacteria added to the diet can improve the growth performance of 1~55-day-old meat geese and enhance their immunity, of which 7.5% of the dosage has the best effect. Liu Changzhong's research showed that fermented feed can reduce the diarrhea rate of growing geese, increase the trypsin, lipase and amylase activities of duodenal contents and pancreatic tissues, and also increase the average daily weight gain of growing geese and reduce the feed-to-meat ratio. Chachaj's study showed that adding 7% fermented soybean meal to turkey diets can significantly increase the height of villi and the ratio of villi, and improve the tissue structure of the small intestine. When the addition level is 9%~10%, it can significantly increase the weight of turkey and improve its growth performance. Fermented feed also stimulates the turkey's immune system and antioxidant system. In summary, fermented feed also has a good effect in the production of goose and other poultry, and has a positive impact on poultry growth performance, intestinal flora, meat quality and egg quality.
Summary
Fermented feed has the characteristics of good palatability, high content of nutrients such as protein and amino acids, and plays an important role in improving poultry production performance, product quality and reducing the concentration of harmful gases in the house, and has broad development prospects and application value. In the process of practical application, due to the differences in the nutritional composition of fermentation raw materials, fermentation strains, fermented feed, dosage and moisture content in the diet, there are certain differences, and their functions and process technologies need to be further explored and studied. In addition to the application of probiotics for fermentation, bacterial enzyme synergy is also a way to improve feed utilization, feed nutrients and feed flavor.
