酵母細(xì)胞壁對腸道菌群的促進(jìn)作用

發(fā)布單位:天津瑞孚農(nóng)牧科技集團(tuán)有限公司

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時間：2019-10-31

動物集約化生產(chǎn)是一個極具挑戰(zhàn)性的環(huán)境，因此，增強(qiáng)動物的免疫系統(tǒng)和維持腸道菌群健康可能是提高生產(chǎn)力的關(guān)鍵因素之一；酵母細(xì)胞壁在這一過程中起著重要的作用。
給2d肉雞添加釀酒酵母細(xì)胞壁（0.5kg/MT，釀酒酵母是來自甘蔗生產(chǎn)乙醇發(fā)酵的過程中，包含35%左右β-葡聚糖（1，3和1，6）和20% 甘露寡糖（MOS）），通過口服腸炎沙門氏菌（SE）感染。試驗(yàn)包含空白對照組（無任何處理）、酵母細(xì)胞壁組（未感染SE）、感染SE組（未添加酵母細(xì)胞壁）和酵母細(xì)胞壁感染組（添加酵母細(xì)胞壁+感染SE）。通過采集雞只血液進(jìn)行細(xì)胞定量分析。
數(shù)據(jù)顯示，酵母細(xì)胞壁感染組雞只，在感染后2d和6d時，肉雞血液中的標(biāo)記物減少了，這表明腸道的完整性和通透性顯著提高；因?yàn)镾E可以通過菌毛粘附到粘膜上，進(jìn)而產(chǎn)生毒素，導(dǎo)致緊密連接和腸上皮細(xì)胞的損害，入侵并進(jìn)入血流和其他內(nèi)部器官和組織。
與感染SE組和空白對照組比較，酵母細(xì)胞壁感染組肉雞在14d時，從血液到腸道的白細(xì)胞移動減少；當(dāng)免疫系統(tǒng)再細(xì)分時，分析不同的細(xì)胞顯示了更多的抗原呈遞細(xì)胞（APC）、抑制單核細(xì)胞、輔助T淋巴細(xì)胞（CD4，分泌白細(xì)胞介素和刺激可以攻擊抗原的細(xì)胞增殖）。酵母細(xì)胞壁組肉雞對于以上細(xì)胞的分析，以及細(xì)胞毒性T淋巴細(xì)胞（CD8）呈現(xiàn)出一種中間值（介于感染組和空白對照組之間）。
在14d時，酵母細(xì)胞壁感染組雞只的抗沙門氏菌IgA產(chǎn)生量最多，這表明免疫系統(tǒng)的特異性反應(yīng)更快更強(qiáng)，消耗更少的能量和營養(yǎng)，因?yàn)檠装Y反應(yīng)過程似乎減短了。
因此，酵母細(xì)胞壁添加可以幫助肉雞實(shí)現(xiàn)更早和更快的先天免疫激活和反應(yīng)，減少/最小化病原體導(dǎo)致的損害以及造成的性能損失。這種反應(yīng)對處于發(fā)育和繁殖早期階段，或應(yīng)激和環(huán)境挑戰(zhàn)時期的動物尤為重要，它可以預(yù)防和增強(qiáng)動物的抵抗力，從而最大限度地減少進(jìn)一步的損害。

Boosting intestinal microbiota with the yeast cell wall
For a few years, we have been receiving advice from international health organisations about the use of antibiotics in the animal production industry. The World Health Organization (WHO) warned that a lack of effective antibiotics was as serious a threat to security as a deadly disease outbreak. We should focus our attention on a set of measures which promote safe animal growth and mainly act in the prevention of diseases.
The role of intestinal microbiota
Many studies prove that beyond antibiotics’ immediate impact on microbiota, these types of medicines also affect the genetic expression, protein activity, and general metabolism of intestinal microbiota. As well as increasing the immediate risk of infection, the microbial changes caused also have long terms effects on the basic immune system.
Animals’ intestinal microbiota plays an important role in regulating their immune systems, since it not only modulates various physiological, nutritional, metabolic and disease-fighting processes, but can also alter the physiopathology of illnesses, conferring resistance, or promote enteric parasitical infections. Natural intestinal bacteria act as molecular adjuvants which provide indirect immunostimulation, helping the organism defend itself against infections.

Immune system – first line of defence
Broilers have a large quantity of lymphoid tissue and immune system cells in their intestinal mucosa, called the GALT (gut-associated lymphoid tissue), which in turn constitutes the MALT (mucosa-associated lymphoid tissue). The GALT is constantly exposed to food antigens, microbiota, and pathogens, and needs to identify components which are present in the intestinal lumen and which could present a possible threat to the animal. The immune system’s first line of defence is composed of phagocytic cells (macrophages, heterophiles, dendritic cells and natural killer cells), which have Toll-type receptors on their surface. These receptors recognise microbial standards and induce an immediate innate immune response. After this activation and phagocytosis, the phagocyte (antigen-presenting cell – “APC”) presents a processed fragment of the antigen and a chain reaction is initiated against it. The innate immune system’s recognition of pathogens first triggers immediate innate defences and, subsequently, the activation of the adaptive immune response.
It is important to emphasise that this series of responses of the innate immune system requires several nutrients, especially metabolic energy, since it is a nonspecific and pro-inflammatory response, but necessary to control the proliferation, invasion, and damage caused by the antigen in the animal organism. However, a prolonged pro-inflammatory response may lead to secondary diseases, immunosuppression, maintenance of immune homeostasis, intestinal dysbiosis, and finally, decline in performance and mortality.

Decreasing the occurrence of immunosuppression
A correct program of measures, including balanced nutrition, vaccination, reduction of stress factors, good management and animal well-being practices, can considerably decrease the occurrence of immunosuppression. Adding dietary additives, which act in the modulation of the innate immune system and microbiota, improves the defence response against potential challenges.
The yeast cell wall Saccharomyces cerevisiae (ImmunoWall, ICC Brazil) is derived from the process of sugar cane fermentation in ethanol production, and is made up of around 35% β-glucans (1,3 and 1,6) and 20% Mannan-Oligosaccharides (MOS). β-glucans are recognised for their phagocytic cells, encouraging them to produce cytokines which will initiate a chain reaction to induce immunomodulation and enhance the responsiveness of the innate immune system. On the other hand, MOS are able to agglutinate type-1 fimbriae pathogens and various strains of Salmonella and Escherichia coli.

Improved intestinal integrity

A recent study conducted by Beir?o et al. (2018), in which broilers received ImmunoWall supplements (0.5 kg/MT) and were infected with Salmonella Enteritidis [SE] (via an oral dosage of 108 CFU per broiler) at two days of age, showed that from four to eight days of age (two and six days post-infection, respectively), the yeast cell wall product reduced the passage of the marker (Dextran-FITC, 3-5 kD) into the challenged broilers’ blood stream. These results show a significant improvement in intestinal integrity and permeability, since SE is a bacterium capable of sticking to the mucosa through its fimbriae, producing toxins and causing damage to tight junctions and enterocytes, invading them and translocating them into the blood stream and other internal organs and tissues .


文章來源：豬營養(yǎng)國際論壇
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