At present, science and technology workers in related fields around the world are actively exploring alternatives to antibiotics. Probiotics, as a new type of feed additive, have received much attention in recent years. Studies have confirmed that probiotic preparations have good biological functions and can be used in animal production to improve intestinal flora balance, prevent diarrhea in animals, increase nutrient utilization, and improve production performance. However, most of the probiotic-producing strains are susceptible to the acidic environment when passing through the gastrointestinal tract of the animal's gastrointestinal tract, resulting in fewer effective bacteria and a lower survival rate in the post-intestine segment. Therefore, the effective function of the probiotic effect of the probiotic preparation is limited. Studies have shown that although oligosaccharides do not have a nutritive effect and are not decomposed by animal digestive enzymes, they can be selectively utilized by beneficial microorganisms after reaching the intestines of the digestive tract, thereby promoting beneficial intestinal flora. Proliferation plays a role in improving the health of the host and improving production performance. Therefore, the combined use of microecological preparations and oligosaccharides has received extensive attention in recent years.
1 The current status and problems of the use of feed probiotics
1.1 Status of use of feed probiotics
The probiotic feed additive is a live bacterial preparation which is beneficial to human and animal safety and is used for feed additives by a special process such as cultivation, fermentation and drying of known beneficial microorganisms. Many studies have shown that the use of probiotics in animal production can inhibit the growth of intestinal pathogens, gradually reduce them, and gradually make beneficial microorganisms become dominant bacteria, thereby preventing animal diarrhea, reducing mortality and increasing animal weight gain. And nutrient utilization, improve its production performance. In recent years, with the continuous development of research on feed microorganisms, more and more probiotic preparations have been developed. In 1998, the United States Food and Drug Administration and the Association of Feed Control Officials announced that there are 45 species of microbes that can be directly fed and safe. There are also 16 kinds of feed-grade microbial strains approved by the Ministry of Agriculture of China in 2008. Common dosage forms of probiotic preparations mainly include liquid preparation, lyophilized preparation, powder, capsule preparation, ointment preparation, aerosol and the like. At present, microecological preparations have been studied and applied in the production of monogastric animals, herbivores and aquatic animals, and have shown good results.
1.2 Limitations and solutions for feed probiotics
Probiotics are mainly live bacterial preparations, which are susceptible to storage, processing, transportation and other conditions in actual production applications, and after entering the digestive tract of animals, under the action of gastric acid, bile acid and aerobic conditions, probiotics The growth and reproduction will be hindered, which will affect its probiotic effect in the intestine. Therefore, how to more effectively exert the probiotic effect of probiotics is the focus of research on microecological preparations today. The combination of probiotics and oligosaccharides can make probiotics use oligosaccharides as nutrients, increase their survival rate in the low pH and aerobic environment of the intestines and continue to multiply, thereby promoting the proliferation of probiotics and promoting probiotics. The effect is played. Therefore, oligosaccharides have been considered as proliferative factors of probiotics, and are used in combination in animal production to improve animal performance and health by effectively improving intestinal flora balance.
2 Mechanism of action of oligosaccharides and probiotics in combination
2.1 Oligosaccharides enter the post-digestive intestines to play a role.
Mammalian digestion of carbohydrates is mainly limited to α-1,4 glycosidic bonds, which produce endogenous carbohydrate-digesting enzymes such as salivary amylase, pancreatic amylase, and pancreatic maltase that decompose other glycosidic bonds. Weak or unable to break down. The functional oligosaccharides are mainly bound by β- 1,2 glycosidic bonds and α-1,6 glycosidic bonds, so they are largely incapable of being digested by mammals, and due to the acid resistance of oligosaccharides It has a strong basicity, so that it can smoothly pass through the anterior digestive tract such as the stomach and small intestine and directly reach the posterior digestive tract such as the large intestine. The digestive intestine segment of a single stomach animal is a place for a large number of microbial activities, and the beneficial bacteria can produce enzymes for cutting and hydrolyzing various glycosidic bonds, thereby being capable of digesting and utilizing oligosaccharides. Therefore, oligosaccharides are not degraded by the digestive enzymes of the animal's gut, but most of the intestines are used by microorganisms to exert their beneficial effects.
2.2 Oligosaccharide Selectively Promotes Probiotic Proliferation
Oligosaccharides can be utilized by beneficial bacteria such as bifidobacteria and lactobacilli in the intestines, so that they can be multiplied and cannot be used by harmful bacteria such as Escherichia coli, Clostridium, Prostatus, and Enterobacter. This is because a beneficial bacteria such as bifidobacteria or lactobacilli can produce an enzyme system that digests oligosaccharides, and cleaves the terminal or intermediate glycosidic bond of the oligosaccharide, thereby obtaining nutrients using the oligosaccharide. For example, the activities of α,β-galactosidase and α,β-glucosidase capable of digesting oligosaccharides produced by bifidobacteria are significantly higher than those of other bacteria. Most harmful bacteria cannot produce these enzymes or have low activity, so oligosaccharides cannot be used for proliferation. On the other hand, not every beneficial bacterium can utilize various oligosaccharides, and not every oligosaccharide can be utilized by various beneficial bacteria, and their utilization has bidirectional selectivity. One bacterium can only effectively utilize one or several oligosaccharides, and an oligosaccharide can only effectively proliferate one or several bacteria. The use of different oligosaccharides by different bacteria is different. Therefore, the beneficial bacteria in the intestine selectively utilize oligosaccharides and rapidly proliferate in the intestinal tract, thereby reducing the growth of pathogenic bacteria in the intestinal tract.
2.3 Probiotics can promote the decomposition of oligosaccharides and produce beneficial metabolites.
Probiotics produce enzymes that promote the breakdown of oligosaccharides in the post-animal digestive tract. These enzymes promote the glycolysis of functional oligosaccharides to produce many beneficial metabolites. The pyruvic acid produced can participate in the metabolism of nitrogen and the metabolism of lipids in the body through the Krebs cycle and acetyl CoA, thereby realizing the mutual conversion of sugar, fat and amino acids in the body. The resulting volatile fatty acid (VFA) can be used as a nutrient passive object, while also reducing the pH and redox potential in the intestinal tract, thereby inhibiting the growth of pathogenic bacteria and regulating the normal peristaltic function of the intestinal tract. However, butyric acid in volatile fatty acids can also promote the formation of cells to repair the intestinal mucosa, which can greatly improve the occurrence of intestinal inflammation and reduce diarrhea in animals. Therefore, probiotics interact with oligosaccharides to produce beneficial metabolites, and it is also one of the mechanisms of action of probiotics and oligosaccharides.
3 Research and application status of probiotics and oligosaccharides in pig production
As mentioned above, the use of probiotics has shown good results in pig production. In order to further enhance its probiotic characteristics and fully play the role of beneficial bacteria, researchers have begun to explore the effects and effects of the use of probiotics and oligosaccharides in pig production. At present, research in this area has been carried out in piglets, growing pigs and finishing pigs, but there are relatively many studies on piglets.
3.1 Improve pig production performance
More experimental studies have shown that adding a certain proportion of probiotics and oligosaccharides in the diet can improve the growth performance of pigs, increase the feed intake of pigs, reduce the ratio of feed to meat, and reduce the incidence of diseases such as diarrhea. Huang Junwen and others add piglet diets
G. natto and mannooligosaccharides reduced the diarrhea rate of early weaned piglets, and the low dose combination of Bacillus natto and mannooligosaccharides could increase the daily weight gain of piglets and improve the growth performance of piglets. Dai Zhaolai and other studies have shown that the combination of lactic acid bacteria and chemical probiotics for feeding and weaning piglets can significantly reduce the diarrhea rate of the two stages of piglets, increase the daily weight gain of piglets after weaning, and reduce the feed weight gain ratio. Better than using lactic acid bacteria or chemical probiotics alone. Zhang Maohua et al. added xylooligosaccharides and probiotics to the growing pig diet to significantly improve the growth performance of the growing pigs. The daily gain was 14.1% higher than that of the control group supplemented with only the basic diet. 5%, feed intake increased by 10%, and better than the single addition of probiotics and xylooligosaccharides. Wu Yicao and other studies have shown that the combined use of mannooligosaccharides and lactic acid bacteria has no synergistic effect on improving the growth performance of piglets. The results of Estrada et al. also showed that the combined feeding effect of oligofructose and Bifidobacterium longum was not superior to that of probiotics alone. The main reasons for these different research results may be different oligosaccharide species, different degrees of polymerization of different oligosaccharides, different oligosaccharides and different probiotics, different compatibility ratios, animal species stages, feeding environment and other conditions. different.
3.2 Improve pig intestinal health
The combination of oligosaccharides and probiotics makes it easier to obtain specific substrates for probiotics, thereby increasing the effective number of probiotics, improving the structure of the intestinal flora, and promoting intestinal health and health. Huang Junwen and other research results show that the combination of natto and mannan oligosaccharide can significantly reduce the pH value of the intestinal segments below the jejunum of piglets. When the mannooligosaccharide is combined with natto, the number of lactobacilli on the contents and the mucosa is increased, and the number of E. coli is decreased, and the two are synergistic. When natto bacteria and 1 g/kg of mannooligosaccharide were used at the same time, the ratio of intestinal villus height and villus height/crypt depth was significantly increased. In addition, Fan Guoge and other studies also showed that probiotics and oligosaccharides were significantly increased in the 0.10% compatibility group compared with the probiotic group to increase the apparent digestibility of crude protein, fat, calcium and phosphorus, and the number of lactic acid bacteria in the feces. Also higher than the probiotic group. Chen Xudong and other studies have shown that the combination of 0.2% Bacillus and 0.4% oligofructose has no significant effect on the intestinal bacteria Escherichia coli and Salmonella, but the number of Bacillus in the combined group is significantly higher than that of the Bacillus group alone. The number of aerobic bacteria in the ileum segment of the combined use group was significantly lower than that of the Bacillus group alone. Explain that the use of compatibility will promote the transformation of piglet intestinal micro-ecological balance in a direction beneficial to the body. The Shim study also showed that the number of anaerobic lactobacilli in the feces of 0.25% and 0.2% oligofructose and compound probiotics was significantly higher than that of the control group, indicating a significant interaction between the two. The results of Herich et al. showed that the combination of Lactobacillus casei and oligofructose significantly reduced the total anaerobic and lactobacilli in weaned piglets compared with lactic acid bacteria alone. It can be seen from the above results that although the compatibility of probiotics and oligosaccharides is different in other aspects, the results are similar in terms of increasing the number of probiotics in the intestine and improving the intestinal flora. Interaction.
3.3 Improve pig immune function
Probiotics and oligosaccharides can stimulate the animal's immune system through a series of ways to improve the body's resistance to pathogenic substances, thereby improving immune function. Therefore, the combination of probiotics and oligosaccharides can improve the intestinal micro-ecological balance, allowing the body to exert normal physiological functions and reduce the occurrence of various diseases. Wu Wei and other studies have shown that the combination of 0.1% Bacillus preparation and 0.4% oligofructose can significantly increase the blocking rate of piglet antibody in piglets for 14d and 21d, and the IgG level of piglets in the compatibility group is significantly higher than that when used alone. The group indicates that the combination of probiotics and oligosaccharides has a synergistic effect on improving the immune function of pigs. Huang Junwen and other studies have also shown that the combination of natto and mannooligosaccharides can increase the levels of CD3+ and CD4+ in piglets' blood, and reduce the content of serum malondialdehyde (MAD), which can improve the immune and antioxidant functions of piglets. . Shim et al. combined 0.2% oligofructose and 0.3% probiotics to form a synbiotic, and studied its effects on blood lymphocytes and neutrophils in suckling piglets. The results showed that the compatibility of oligofructose probiotics on blood immune index of piglets There was no synergy in the effects, and the differences between the groups were not significant. Therefore, the differences in research results in this area need further verification and discussion.
4 Summary
At present, there are still many cases of non-standard use of antibiotics in the breeding process of pigs. The problem of antibiotic residues and drug resistance cannot be underestimated. As a new, green, residue-free additive, probiotics play a progressive role in replacing antibiotics in aquaculture production. In order to better exert its probiotic effect in animal production and to selectively promote the function of probiotic growth, oligosaccharides have been considered to be compatible with probiotics to exert synergistic effects. However, the current research in this area is mostly basic and applied research, mainly focusing on the production performance, intestinal microflora, immune function, etc., there is no systematic, targeted research and less mechanistic research. Therefore, in the future research, we should also pay attention to the selective compatibility of probiotics and oligosaccharides, and screen the oligosaccharide species that can promote the proliferation of probiotics to maximize the probiotics, and play the role of probiotics more effectively and to a greater extent. In addition, the ratio of probiotics to oligosaccharides and its mechanism of action should also be systematically studied to enable the most economical and direct promotion of the role of probiotics, thereby improving animal performance and improving animal health.
Compatibility of probiotics and oligosaccharides and their research and application status in pig production
Wang Jing, Ji Haifeng, Wang Sixin, Zhang Dongyan, Liu Hui, Wang
Institute of Animal Husbandry and Veterinary Medicine, Beijing Academy of Agriculture and Forestry Sciences,
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