瘤胃微生物的肽营养

自６０年代以来,瘤胃微生物的氮素营养研究大体经历了非蛋白氮利用研究（Ｈｏｌｔｅｒ等,１９６８）〔１〕、饲料蛋白质降解（新体系）研究（Ｏｒｓｋｏｖ等,１９７９）〔２〕和肽营养研究（Ｗａｌａｃｅ等,１９８９;Ｙａｎｇ等,１９９２）〔３～４〕三个阶段。最近...     

蛋白质营养中小肽的研究新进展

蛋白质营养一直是动物营养研究的核心问题．过去的观点认为,动物采食的蛋白质在消化道内蛋白酶和肽酶的作用下降解为游离氨基酸才能被动物直接吸收。但最近的研究表明．蛋白质在动物消化道中消化酶作用下的水解产物大部分为2或3个氨基酸残基的小肽,它们是以完整形式被吸收并进入循环系统而被组织利用的。动物营养学家也发现．     

瘤胃微生物肽营养研究进展

本文就瘤胃内肽降解的微生物学、微生物摄取肽的机制、影响微生物摄取肽的因素、微生物对肽的营养需要、肽营养与微生物生长、肽营养对微生物发酵环境与饲料养分消化的影响、肽乙酰化保护与营养以及离子载体对肽降解的影响进行了综述和重点讨论 ,并对瘤胃微生物肽营养未来研究做了展望     

瘤胃微生物对肽的利用

围绕瘤胃微生物对肽的利用这一主题,揭示肽在瘤胃内的积累现象及肽对瘤胃微生物的促生长作用,从瘤胃微生物肽酶的活性、肽的理化参数对肽在瘤胃内代谢的影响及合成肽的代谢研究３个方面勾画出了当前反刍动物营养学研究领域内肽的代谢研究现状,并指明了今后的研究方向。     

瘤胃微生物纤维素酶的研究与应用前景

瘤胃是反刍动物复胃（多室胃）的组成部分之一，而瘤胃微生物则是指栖息在瘤胃中的微生物，主要包括细菌，真菌和原生动物，其中，瘤胃细菌和瘤胃真菌能分泌纤维素酶，纤维素酶是多组分复合酶，主要为内切型葡聚糖酶，外切型葡聚糖酶和β-葡萄糖苷酶，由于瘤胃纤维素酶对纤维素有较强的降解能力。故瘤胃微生物纤维素酶在降解纤维素，开发新饲料，作为新式酶源和处理有机垃圾等方面有广阔的应用前景。     

瘤胃微生物对肽的利用

围绕瘤胃微生物对肽的利用这一主题,揭示肽在瘤胃内的积累现象及肽对瘤胃微生物的促生长作用,从瘤胃微生物肽酶的活性、肽的理化参数对肽在瘤胃内代谢的影响及合成肽的代谢研究３个方面勾画出了当前反刍动物营养学研究领域内肽的代谢研究现状,并指明了今后的研究方向。     

活性肽的营养作用与应用

传统的蛋白质营养理论认为蛋白质的营养即是氨基酸的营养。这一理论是Dogman在1900年提出的。当时他认为在人和动物胃肠道,蛋白质必须被消化成游离氨基酸才能被小肠粘膜细胞吸收和转运。由此,形成了粗蛋白质、氨基酸、必需氨基酸、可利用氨基酸、理想蛋白质等理论。并在生产实践中发挥着指导作用。但传统理论表现出局限性,合成氨基酸取代完整蛋白质的数量是有限的,在快速生长的猪、鸡的日粮中,若保持能量水平一致,动物将不能保持最佳的生产性能和饲料效率（Fancher和Jensen．1989：Men．donca和Jensen,1989;Pinchasov等,1990;Kephart和Sherritt,1990）。近年来,人们对消化过程中蛋白质消化释放的活性肽在蛋白质营养中的作用越来越关注。认识肽的营养作用,利用具有潜在生物活性作用的肽,调控动物的营养生理代谢,为进一步提高动物生产性能和提高畜禽生产效益提供新的手段。     

过瘤胃氨基酸的作用与应用

反刍动物蛋白质营养的实质和核心是氨基酸营养,由于瘤胃微生物的作用,反刍动物日粮中直接添加氨基酸,会在瘤胃中部分或完全降解,最终到达小肠可被吸收利用的氨基酸量减少。因此氨基酸过瘤胃保护非常重要。许多研究表明,在日粮中添加过瘤胃氨基酸（Rumen—Protected Amino Acids,RPAA）是为反刍动物提供理想小肠氨基酸简便、直接而又有效的调控方法,对提高饲料利用率、减少蛋白质和氨基酸浪费、降低生产成本、提高高产反刍动物生产性能具有重要意义。     

过瘤胃营养及在奶牛饲养中的应用

传统的反刍动物营养研究主要集中在瘤胃中的微生物对饲料中养分的消化代谢机制和对各种营养的适宜需要量及需要形态上,其目标是最大程度地发挥瘤胃微生物对饲料纤维的消化利用能力及对饲料蛋白质尤其是非蛋白氮的利用效率,以向体组织提供足量且比例适宜的挥发性脂肪酸及增加流入小肠的微生物物质,特别是含可消化氨基酸丰富而平衡的微生物蛋白质。随着人类对家畜生产性能的追求,在人类的选育下,家畜的生产性能有了极大的提高。高产动物的营养需要和供给之间出现了不协调的现象,反刍动物的瘤胃微生物营养已不能完全满足其在能量、蛋白质、必需氨基酸和维生素等方面的需要。因此,近年来,反刍动物的营养研究逐渐向肠道营养代谢扩展,如研究小肠可消化蛋白营养需要量、不同条件下过瘤胃氨基酸、淀粉和脂肪对高产反刍动物生产性能的影响。国内外已进行了大量有关奶牛过瘤胃营养的研究,并已开发了许多过瘤胃产品在生产中开始使用。     

小肽营养在反刍动物生产中的应用

传统的蛋白质营养理论认为,蛋白质在肠道中都被消化成氨基酸,然后通过肠壁被机体吸收,蛋白质营养就成了氨基酸营养。事实上,许多试验表明,用纯化组合日粮或低蛋白质平衡氨基酸日粮饲喂动物,并不能使其表现出最佳生产性能。随着研究的深入开展,产生了一些蛋白质营养的新认识和新观点,其中最为重要的应是小肽营养的理论,已逐渐被接受,蛋白质营养包括氨基酸营养和小肽营养。当蛋白质以小肽形式供给时,可提高动物对蛋白质的利用率,进一步发挥动物的生产潜能,具有增强动物免疫、防病抗病能力、改善动物产品品质等重要作用。对于反刍动物的蛋白质…     

鲤鱼肠道中小肽与血液中肽的关系研究

为了研究鲤鱼肠道完整吸收小肽与肠道中小肽的关系,用6．25％酶解酪蛋白、酸解酪蛋白、酪蛋白溶液和生理盐水对鲤鱼进行肠道灌注试验(1ml／100g体重),20min后尾静脉采血制备血浆,用高效液相色谱仪分析。结果表明,鲤鱼血浆中肽量的增加与肠道提供的肽种类和数量有关,鲤鱼肠道能够完整地吸收某些小肽进入血液循环。     

不同结构对囊素样肽的免疫活性影响

化学合成单拷贝（BS）、30拷贝串联（KG30）和30拷贝分支结构（MAP）3种不同结构的囊素样肽,通过体外外周血淋巴细胞刺激增殖试验、杂交瘤细胞抗体分泌刺激试验、E-玫瑰花环试验和体内小鼠腹腔巨噬细胞吞噬功能、新城疫疫苗免疫应答的测定,比较了其免疫增强活性。结果表明,BS和MAP的活性显著高于KG30,BS体外试验活性优于MAP,而MAP体内试验活性优于KS。结构对囊素的活性有显著影响,以分支结构的囊素增强免疫效果最好。     

Effects of laidlomycin propionate and monensin on the in vitro mixed ruminal microorganism fermentation.

The objective of this study was to compare the effects of laidlomycin propionate and monensin on the in vitro fermentation of ground corn, Trypticase, or alfalfa hay by mixed ruminal microorganisms. Ruminal fluid was collected from two steers fed 9.27 kg DM of a high-concentrate (62.2% ground corn and 17.4% cottonseed hulls) diet per day and composited. In the first study, no ionophore was included in the diet; the diet in the second study contained 11.1 g of laidlomycin propionate per ton of feed. The animals were allowed an adjustment period of 14 d for each dietary treatment before samples were collected. When ruminal fluid from unadapted animals was used, both monensin and laidlomycin propionate decreased (P<.05) CH4 concentration and the acetate:propionate ratio with ground corn and alfalfa hay. Monensin reduced (P<.05) in vitro dry matter disappearance of alfalfa and increased (P<.05) final pH in the ground corn and alfalfa hay fermentations. Both laidlomycin propionate and monensin decreased (P<.05) concentrations of acetate, propionate, isobutyrate, isovalerate, CH4, and NH3 in Trypticase fermentations. When ruminal fluid from adapted animals was used, both ionophores still reduced the concentrations of most fermentation products. However, there was generally less inhibition compared with fermentations inoculated with unadapted mixed ruminal microorganisms. In the presence of 5 mM maltose, mixed ruminal bacteria produced high concentrations (10 to 11 mM) of lactate, and addition of both ionophores to these fermentations was effective in reducing (P<.05) lactate production. In conclusion, laidlomycin propionate alters the mixed ruminal microorganism fermentation in a manner similar to monensin, but, at the concentrations used in this study, monensin seemed to be a more potent inhibitor.     

鱼类组蛋白衍生抗菌肽与其抗菌的关系

<正>通常,抗菌肽是动物免疫防御系统在外界条件刺激下,由基因编码、核糖体合成,用以对抗外源性病原体的一类含有20～60个氨基酸残基的多肽类物质。其具有快速、广谱、非特异性的抗菌特性,以及部     

利用瘤胃微生物体外发酵饲料饲喂母猪的试验

运用仿生学原理,利用牛瘤胃中纤毛虫及细菌等生物,体外发酵饲料合成菌体蛋白喂猪,开发新的蛋白饲料资源。选用经产母猪23头饲喂瘤胃微生物体外发酵饲料作为试验组,23头饲喂同样未经发酵处理的饲料作为对照组。结果表明,试验组窝产仔数、初生重、断奶重、断奶成活率、断奶窝重、药费支出及猪只健康状态明显优于对照组。因此,瘤胃微生物体外发酵饲料喂猪,猪食欲强,催肥快、肉质好、抗病性强,仔猪成活率高,断奶重大,发病率低,药物费用支付少,而且技术简单,操作方便,饲料贮存量大,无毒无害,对环境保护有积极作用,很适合大型养猪场及农村家庭饲养,具有较高的应用价值。     

Evidence for a relationship between bovine erythrocyte lipid membrane peculiarities and immune pressure from ruminal ciliates

Erythrocytes of bovines and other ruminants have a strikingly anomalous phospholipid composition, with low or absent phosphatidylcholine (PC) together with high sphingomyelin (SM) content. Here, we report the presence in normal bovine serum of high levels of anti-phospholipid antibodies of IgM isotype against, PC and the phosphono analogue of phosphatidylethanolamine, aminoethylphosphonolipid (AEPL), normally produced by rumen ciliates. In contrast, no antibodies were detected against SM or N-acyl-phosphatidylethanolamine (NAPE), the major components of bovine erythrocytes. In addition, we found that exposure of the ciliate Tetrahymena thermophila to bovine serum results in rapid lysis, an effect that was inhibited by adsorption of the serum with SM/AEPL liposomes. Furthermore, incubation with bovine serum had a similar effect on freshly obtained ruminal ciliates, and the lytic activity was eliminated by pre-adsorption of the serum with SM/PE liposomes. The ruminant mode of life with its concomitant ciliate fauna is hereby linked to the peculiar conformation of bovine erythrocyte membranes. We propose that the unique phospholipid composition of bovine erythrocytes appears as an evolutionary adaptation to tolerate the lytic effects of anti-phospholipid antibodies generated against AEPL, a membrane component of the huge mass of ruminal ciliates, necessary commensals of this group of mammals.     

Screening of exogenous enzymes for ruminant diets: relationship between biochemical characteristics and in vitro ruminal degradation

With the objective of developing a rational approach for the selection of feed enzymes for ruminants, 22 commercial enzyme products were examined in terms of protein concentration, enzymic activities on model substrates, and hydrolytic capacity, the latter determined from the release of reducing sugars from alfalfa hay and corn silage. An in vitro ruminal degradation assessment was carried out using the same substrates, untreated or treated with the 22 enzyme products at 1.5 microL/g forage DM. Stepwise regressions were then performed to establish relationships between these factors. Protein concentration and enzymic activities explained at least 84% (P < 0.01) of the variation in the release of reducing sugars from alfalfa and corn silage. Alfalfa DM degradation after incubation with ruminal fluid for 18 h was positively related to xylanase activity (R2 = 0.29, P < 0.01), but the same activity was negatively related to DM degradation of corn silage (R2 = 0.19, P < 0.05). Protease activity explained a further 10% of the alfalfa DM degradation (P < 0.10). Following sequential steps involving the determination of rate and extent of DM and fiber degradation, the best candidates for alfalfa and corn silage were selected. Enzyme products effective with alfalfa hay seemed to exert part of their effect during the pretreatment period, whereas enzymes effective with corn silage worked exclusively after ruminal fluid was added. This finding suggests that different modes of action of exogenous enzymes are attacking different substrates and may partly explain enzyme-feed specificity. In alfalfa, it seems that effective enzymes work by removing structural barriers that retard the microbial colonization of digestible fractions, increasing the rate of degradation. In corn silage, effective enzymes seem to interact with ruminal enzymes to degrade the forage more rapidly, which is consistent with previous findings of synergism between exogenous and ruminal enzymes.     

牛磺酸与泌乳功能的关系探讨

本文介绍了牛磺酸对内分泌的影响,分析了牛磺酸和泌乳的关系.     

反刍兽异嗜癖与瘤胃内环境的关系

反刍兽异嗜癖 ,是牛、羊、鹿等动物常发的一种现象 ,一般人们不认为是一种独立的疾病 ,但这种现象在牛、鹿发生非常普遍 ,尤其在豫西丘陵山区 ,牛的发生率可达 30 %以上 ,局部地区可达 80 %。鹿的异嗜发生率可达 90 %以上 ,有些鹿场可达 1 0 0 % ,严重影响着草食动物的发展。但