微生物介导反刍动物瘤胃氨生成及其对瘤胃功能的影响

反刍动物瘤胃中栖息着丰富多样的微生物,其在瘤胃内氨生成过程中发挥了重要的作用。微生物介导的氨基酸脱氨基作用和非蛋白氮水解作用是瘤胃内氨生成的主要途径。微生物介导了瘤胃内氨的生成,同时瘤胃内产生的氨也会反馈影响微生物菌群结构及瘤胃上皮功能,进而影响瘤胃发酵及宿主健康。本文主要综述了瘤胃微生物在介导氨生成中的作用和氨对瘤胃消化及瘤胃上皮功能的影响,以期对后续研究有所启发。     

表面活性剂调控瘤胃营养功能研究进展

表面活性剂分为化学表面活性剂和生物表面活性剂两大类,非离子表面活性剂和生物表面活性剂作为新型反刍动物饲料添加剂,可通过改变瘤胃液乳化特性、瘤胃微生物种群数量、分泌酶活性、酶吸附能力和瘤胃发酵模式,来增强瘤胃微生物对粗饲料的降解能力,进而提高反刍动物生产性能。综述提出了表面活性剂在反刍动物瘤胃营养调控领域的研究重点。     

瘤胃甲烷菌及甲烷生成的调控

甲烷菌属于古细菌 ,参与有机物的厌氧降解 ,生成甲烷。反刍动物瘤胃内甲烷的生成损耗 2 %～ 12 %的饲料能量 ,并且通过嗳气排入大气。甲烷不仅是温室气体之一 ,而且还会破坏大气臭氧层。每年全球反刍动物排放大量的甲烷 ,减少瘤胃内甲烷的生成对提高饲料能量利用率和改善环境具有重要意义。近年来 ,有关瘤胃甲烷菌及甲烷生成调控的报道日益增多。概述甲烷菌的特性以及瘤胃内甲烷生成的途径 ,综述甲烷生成的调控手段 ,主要包括去原虫、日粮配合、添加电子受体、增加乙酸生成菌等方法     

奶牛瘤胃微生物研究进展和趋势

近年来在奶牛试验中,对瘤胃微生物的研究引起了人们越来越多的兴趣。这些研究的目的多是将微生物组成变化与日粮组成、宿主生产性能(如饲料效率,产奶量,乳脂等)、健康(如瘤胃酸中毒和亚急性酸中毒)以及环境(如甲烷排放)联系起来,另外还有一些研究则强调了微生物在多种反刍动物瘤胃发育中的作用。关于奶牛瘤胃微生物的大部分发现都是基于扩增子测序,可以揭示瘤胃微生物的分类组成,以及在不同处理条件下瘤胃菌群的变化。尽管新兴的宏基因组学和宏转录组学能够深入探索瘤胃微生物的功能,但在数据分析和解释方面也带来了更多的挑战,如目前大多数论文都严重依赖于相关性和推测分析。综述了奶牛瘤胃微生物研究的进展和局限,包括瘤胃微生物与产奶效率、甲烷排放以及瘤胃发育的关系,以及奶牛瘤胃微生物未来的研究趋势。     

试论微生态制剂对反刍动物的作用机制

要了解微生态制剂对反刍动物的作用 ,首先要了解反刍动物瘤胃内的微生态环境和瘤胃微生物对机体的生理效应 ,如同了解自然 ,才能改造自然一样 ,为此 ,许多畜牧专家、微生物和微生态专家都一直从事瘤胃微生物生态系及其生理效应的研究。企图通过复制或调控瘤胃微生物区系来增加产量 ,提高效益。1　反刍动物消化道器官的特殊性反刍动物 (牛、羊、鹿、驼等 )在其长期的历史进化过程中形成了独特的消化系统。其瘤胃分为四个室 ,即瘤胃、网胃、瓣胃和皱胃。前三个胃称为前胃 ,没有胃腺 ,主要靠微生物的发酵作用消化饲料 ,其中瘤胃最大 ,占动物总…     

宏基因组学技术在反刍动物瘤胃微生态系统上的应用研究进展

微生物在自然界中广泛存在,除土壤和水中的微生物最多外,其次在农业畜牧业中反刍动物的瘤胃微生态系统中的微生物中所占比例最多。反刍动物瘤胃微生物由于种类繁多,数量巨大,微生物区系之间关系非常复杂,它们之间寄生共生,共同影响宿主的生长发育和机体代谢,所以是反刍动物营养学研究的热点之一。随着分子生物学技术的发展,宏基因组学技术帮助我们揭开了瘤胃微生物群落的真实面貌,有助于挖掘瘤胃微生物基因库并筛选其中的功能基因,使人们对反刍动物瘤胃微生物群落的研究更加方便、透彻。本文综述了近些年应用宏基因组学技术在反刍动物瘤胃微生态群落系统的应用,旨在对瘤胃微生物功能特征进行更深入的研究,为畜牧科学生产及微生物发酵等相关领域的研究提供科学指导。     

人工瘤胃发酵饲料的制作方法

人工瘤胃发酵饲料,是以各种秸秆粉作为主要原料,借助于瘤胃微生物的发酵作用制作而成的一种猪饲料。在牛羊等反刍动物的瘤胃内,共生着一些微生物,它们的主要作用是能将饲料纤维素分解并转变为对生畜体有营养的物质。为了发展养猪事业,开阔饲料来源,提高猪对粗饲料的利用率,几年来,全国不少地     

瘤胃真菌的营养功能及其应用

在过去几十年里,人们对反刍动物胃肠道消化功能起主导作用的微生物区系的研究取得很大的进展,但主要集中在细菌和纤毛虫上,对瘤胃真菌的描述却很少,这是因为,以前在研究瘤胃微生物时,人们往往采用经纱布或尼龙网过滤后的瘤胃液.这样正好把粘在固体残渣上的真菌滤掉了,因此,看到的只是有鞭毛的细胞,这些细胞被误认为原虫.近年来人们开始转向瘤胃真菌的研究.得知,瘤胃真菌在降解饲料,特别是大颗粒、大片段、植物纤维过程中起着重要作用.本文就瘤胃真菌的特点、形态、在饲料降解中的作用及其应用前景做一综述.     

为动物类专业本科生讲授瘤胃微生物知识点的体会

瘤胃微生物与反刍动物的共生关系是动物类专业本科生必须掌握的重要知识。我们采取问题导向教学方法,使学生较好地掌握瘤胃微生物在反刍动物生长发育中的作用,积极培养学生在科学饲养反刍动物、正确防治瘤胃疾病以及未来开展反刍动物相关研究的素质和能力。     

一株产丁酸羊源拜氏梭菌的筛选及其培养条件优化

【背景】人类和动物消化道内栖息着极其复杂和多样化的微生物群落,这些微生物群落分布在肠道的不同位置并执行着特定的功能。近年来,产丁酸菌逐渐成为微生物领域的研究热点,产丁酸菌主要为产芽孢革兰氏阳性厌氧菌,对肠道健康有重要意义。【目的】从反刍动物瘤胃中筛选出产丁酸菌株并研究其生长特性,进一步优化其培养条件,从而提高产丁酸菌的丁酸产量。【方法】以绵羊瘤胃内容物为样品,运用稀释涂布法进行产丁酸菌的筛选,通过形态学观察和16S rRNA基因序列分析等方法对菌株进行鉴定。通过单因素试验与Box-Behnken design试验相结合,对培养条件进行优化,确定筛选菌株在梭菌增殖培养基(reinforced clostridium medium,RCM)中的最佳产酸培养条件。【结果】经过筛选鉴定得到的菌株为梭菌属的拜氏梭菌(clostridium beijerinckii,CB),命名为拜氏梭菌R8(CB.R8)。对拜氏梭菌R8的培养条件进行优化,得出该菌株在接种量为1.22%、温度为38.45℃、pH6.08和培养时间为64.67h的条件下丁酸产量为2.48g/L。【结论】筛选到1株拜氏梭菌R8,该菌能够在RCM培养基中生长并代谢产生丁酸,具备较高的应用价值。     

Dynamic role of single-celled fungi in ruminal microbial ecology and activities

In ruminants, high fermentation capacity is necessary to develop more efficient ruminant production systems. Greater level of production depends on the ability of the microbial ecosystem to convert organic matter into precursors of milk and meat. This has led to increased interest by animal nutritionists, biochemists and microbiologists in evaluating different strategies to manipulate the rumen biota to improve animal performance, production efficiency and animal health. One of such strategies is the use of natural feed additives such as single-celled fungi yeast. The main objectives of using yeasts as natural additives in ruminant diets include; (i) to prevent rumen microflora disorders, (ii) to improve and sustain higher production of milk and meat, (iii) to reduce rumen acidosis and bloat which adversely affect animal health and performance, (iv) to decrease the risk of ruminant-associated human pathogens and (v) to reduce the excretion of nitrogenous-based compounds, carbon dioxide and methane. Yeast, a natural feed additive, has the potential to enhance feed degradation by increasing the concentration of volatile fatty acids during fermentation processes. In addition, microbial growth in the rumen is enhanced in the presence of yeast leading to the delivery of a greater amount of microbial protein to the duodenum and high nitrogen retention. Single-celled fungi yeast has demonstrated its ability to increase fibre digestibility and lower faecal output of organic matter due to improved digestion of organic matter, which subsequently improves animal productivity. Yeast also has the ability to alter the fermentation process in the rumen in a way that reduces methane formation. Furthermore, yeast inclusion in ruminant diets has been reported to decrease toxins absorption such as mycotoxins and promote epithelial cell integrity. This review article provides information on the impact of single-celled fungi yeast as a feed supplement on ruminal microbiota and its function to improve the health and productive longevity of ruminants.     

Review: Markers and proxies to monitor ruminal function and feed efficiency in young ruminants

Developing the rumen’s capacity to utilise recalcitrant and low-value feed resources is important for ruminant production systems. Early-life nutrition and management practices have been shown to influence development of the rumen in young animals with long-term consequences on their performance. Therefore, there has been increasing interest to understand ruminal development and function in young ruminants to improve feed efficiency, health, welfare, and performance of both young and adult ruminants. However, due to the small size, rapid morphological changes and low initial microbial populations of the rumen, it is difficult to study ruminal function in young ruminants without major invasive approaches or slaughter studies. In this review, we discuss the usefulness of a range of proxies and markers to monitor ruminal function and nitrogen use efficiency (a major part of feed efficiency) in young ruminants. Breath sulphide and methane emissions showed the greatest potential as simple markers of a developing microbiota in young ruminants. However, there is only limited evidence for robust indicators of feed efficiency at this stage. The use of nitrogen isotopic discrimination based on plasma samples appeared to be the most promising proxy for feed efficiency in young ruminants. More research is needed to explore and refine potential proxies and markers to indicate ruminal function and feed efficiency in young ruminants, particularly for neonatal ruminants.     

Strategies for optimizing nitrogen use by ruminants

The efficiency of N utilization in ruminants is typically low (around 25%) and highly variable (10% to 40%) compared with the higher efficiency of other production animals. The low efficiency has implications for the production performance and environment. Many efforts have been devoted to improving the efficiency of N utilization in ruminants, and while major improvements in our understanding of N requirements and metabolism have been achieved, the overall efficiency remains low. In general, maximal efficiency of N utilization will only occur at the expense of some losses in production performance. However, optimal production and N utilization may be achieved through the understanding of the key mechanisms involved in the control of N metabolism. Key factors in the rumen include the efficiency of N capture in the rumen (grams of bacterial N per grams of rumen available N) and the modification of protein degradation. Traditionally, protein degradation has been modulated by modifying the feed (physical and chemical treatments). Modifying the rumen microflora involved in peptide degradation and amino acid deamination offers an alternative approach that needs to be addressed. Current evidence indicates that in typical feeding conditions there is limited net recycling of N into the rumen (blood urea-N uptake minus ammonia-N absorption), but understanding the factors controlling urea transport across the rumen wall may reverse the balance to take advantage of the recycling capabilities of ruminants. Finally, there is considerable metabolism of amino acids (AA) in the portal-drained viscera (PDV) and liver. However, most of this process occurs through the uptake of AA from the arterial blood and not during the 'absorptive' process. Therefore, AA are available to the peripheral circulation and to the mammary gland before being used by PDV and the liver. In these conditions, the mammary gland plays a key role in determining the efficiency of N utilization because the PDV and liver will use AA in excess of those required by the mammary gland. Protein synthesis in the mammary gland appears to be tightly regulated by local and systemic signals. The understanding of factors regulating AA supply and absorption in the mammary gland, and the synthesis of milk protein should allow the formulation of diets that increase total AA uptake by the mammary gland and thus reduce AA utilization by PDV and the liver. A better understanding of these key processes should allow the development of strategies to improve the efficiency of N utilization in ruminants.     

Rumen microbiology, biotechnology and ruminant nutrition: The application of research findings to a complex microbial ecosystem

Research on rumen microorganisms has contributed greatly to our understanding of anaerobic microbial ecosystems, and has also influenced feeding practices and nutritional modelling with ruminants. However, it can be argued that rumen microbiology has not yet fulfilled its true potential. Growth-promoting ionophores, antibiotics and microbial feed additives were introduced before their microbiological effects had been determined. A more pro-active role for the microbiologist was predicted with the advent of recombinant DNA technology. Whether ventures in molecular biology can be applied successfully to benefit nutrition and health is likely to depend on whether means can be found for maintaining new strains in vivo.     

Is<Emphasis Type="Italic">Pseudobutyrivibrio xylanivorans</Emphasis> strain Mz5<Superscript>T</Superscript> suitable as a probiotic? An<Emphasis Type="Italic">in Vitro</Emphasis> study

Rumen bacterium Pseudobutyrivibrio xylanivorans strain Mz5T possessed a potent xylanolytic enzyme system consisting of at least 7 different xylan hydrolases with molar mass 27-145 kDa. Three of them were successfully isolated in active native form. This strain produced butyrate and lactate on different saccharides. cis-9, trans-11-Conjugated linoleic acid was also detected in the culture medium. Bacteriocin-like inhibitory substances of Mz5T were active against some strains of rumen bacteria and against selected Salmonella and E. coli isolates from poultry meat. The strain Mz5T retained viability and xylanolytic activity also under not fully anaerobic conditions; its cells attached to the Caco-2 cells so that its successful association with gut epithelial cells may be expected. These in vitro results confirmed several probiotic traits of the isolate Mz5T and justified further in vivo experiments to test its ability to improve animal health and performance.     

The effect of rumen epithelial development on metabolic activities and ketogenesis by the tissue in vitro.

1. An investigation was made on oxygen consumption, glucose and lactate uptake and ketogenesis from butyrate by rumen epithelium in vitro from lambs at various stages of development. 2. Oxygen uptake was decreased by about 35% and glucose uptake by about 90% between 2 weeks and 1/2 year of age. 3. The uptake of L-lactate and the utilization of butyrate as a substrate for respiration were increased during epithelial development. 4. The production of D(-)-3-hydroxybutyrate and acetoacetate from butyrate by the epithelium was largely increased between 4 to 10 weeks of age, independently of rumen fermentation. 5. A synergistic effect of glucose on the production of D(-)-3-hydroxybutyrate and on total ketone bodies from butyrate by the epithelium was observed. It accounted to 40-80% over butyrate depending on the stage of epithelial development.