丁酸在动物体内的作用

<正>丁酸是反刍动物瘤胃和杂食动物结肠中微生物发酵碳水化合物的产物[1],被认为是抗生素的潜在替代物。Dierick等(2002)[2]把短链脂肪酸作为猪日粮中抗生素的替代物而加以使用。丁酸具有较强的杀菌作用,和     

短链脂肪酸在动物体内的生理特点和功能

短链脂肪酸不仅可作为营养物质被吸收利用,而且对机体有着重要的生理功能。就短链脂肪酸在动物体内的来源、吸收、代谢及不同短链脂肪酸在生理功能上的异同等方面进行综述。     

有机硒在动物体内的营养作用

硒作为动物体内重要的微量元素之一,近几年来已广泛应用于畜禽饲料中。国内外大量研究资料证明,硒在动物体内的代谢过程中以有机硒的形态发生作用,其活性大小与硒结合的组分有关,硒蛋氨酸远比无机硒的利用率高。另外有机硒同无机硒相比,具有吸收率高,生物活性强,毒性小,环境污染小等优点,因而已成为目前硒研究的一个热点。1 有机硒的营养有机硒的最基本作用是参与谷胱甘肽过氧化物酶(GSH-Px)合成,GSH-PX广泛存在于所有动物机体的组织中,起保护细胞膜免受自由基对其膜上的不饱和脂肪酸的过氧化伤害,GSH-PX通过还原型谷胱甘肽(GSH)向氧…     

锌在动物体内作用的研究进展

自从1869年Raulin发现锌与生物的生长发育有关之后,人们相继证实锌是大鼠、猪、鸡、火鸡、牛、羊、狗、鹌鹑等动物和人体内不可缺少的微量元素之一。近年来,锌在生物学和医学的很多领域又取得了许多突破性进展,其在体内的代谢作用日益受到更多的学者、养殖场所重视。现根据近期有关文献简介如下。 一、锌对动物生长发育的作用 1.锌对糖、蛋白质、核酸的关系 现已确认,锌是200多种金属酶的组成成分,如碳     

微量元素钒在动物体内的生物学作用

钒是动物体内的必需微量元素。本文概要介绍了近20年来有关钒的生物学作用的研究。目前的研究表明,钒对生长发育、心血管、造血功能、肾脏及代谢均有重要影响,另一方面,钒对动物体内具有一定的毒性。     

微量元素硒在动物体内的营养作用

硒作为动物体内必需的微量元素 ,国内外经大量研究证明 ,硒在动物体内新陈代谢中起着重要作用。当动物体内硒缺乏时 ,畜禽的生产性能下降 ,甚至会使机体发生病变 ,诸如白肌病、桑椹心脏病、繁殖性能下降、脑软化症、腹水症、胰腺变性、渗出性素质病、饮食性肝坏死等等。1　硒的作用及其机理硒具有保护肝脏、心脏、延缓机体衰老的作用。硒是谷胱甘肽过氧化物酶的主要成份 ,故硒能抑制过氧化反应 ,清除有害自由基 ,分解过氧化物。硒具有防癌作用。硒能抑制癌细胞的分裂、增殖 ,具有防癌作用。此外 ,硒具有预防某些有毒金属对动物组织的损害作…     

小肽在动物体内的营养作用

小肽(Small Peptide)是动物在进行蛋白质消化时产生的中间物质,通常情况下是指由2~3个氨基酸缩合而成的寡肽。小肽具有吸收快、能被动物直接利用等特点。传统蛋白质理论认为蛋白质只有分解为游离氨基酸(FAA)才能被动物吸收利用,但是近年来的研究表明,小肽能以完整的形式被动物机体直接吸收利用,并且具有促进蛋白质的合成、促进矿物元素吸收等营养作用。目前,各种小肽制品也逐步应用于动物生产之中。     

微量元素钡在动物体内的生物学作用

钒是动物体内的必需微量元素。本文概要介绍了近20年来有关钒的生物学作用的研究。目前的研究表明,钒对生长发育、心血管、造血功能、肾脏及代谢均有重要影响,另一方面,钒对动物体内具有一定的毒性。     

瘤胃挥发性脂肪酸的作用及影响因素

瘤胃挥发性脂肪酸与反刍动物瘤胃营养以及瘤胃微生物有着密切的关系。反刍动物瘤胃对养分的消化吸收以及微生物动力学可产生大量的挥发性脂肪酸,其主要作用为供能和维持瘤胃环境。本文综述了瘤胃挥发性脂肪酸(VFA)的作用、影响其产生和组成的因素以及其对反刍动物的影响。     

中草药在动物体内抗应激作用的研究

应激是指各种不同的应激因素（如饥饿、饲料突变、寒冷、温热、低氧、过劳、捕捉、密集饲养、生活环境改变、运输、疫苗注射等）所引起的一种全身性非特异性反应，它是生物机体的一种适应性机制。但是，过强的应激反应可导致畜禽生长发育迟缓、繁殖机能障碍、生产性能下降、产品产量和质量降低、甚至引起畜禽死亡，给养殖业带来严重危害。     

Effect of volatile fatty acid infusion on blood plasma free amino acid profiles in growing lambs.

Five ram lambs (average body mass: 25 kg) were given, through a catheter inserted into the left ruminal vein, a total of 28.8 mM sodium acetate, 14.4 mM sodium propionate and 4.8 mM sodium butyrate per kg body mass as a 2-hour infusion. During and at 0, 1, 2, 4, 6, 10 and 24 h after the infusion blood samples were taken from the jugular vein and the blood plasma was assayed for free amino acid (FAA) and immunoreactive insulin (IRI) concentrations. Volatile fatty acid (VFA) infusion significantly decreased the blood plasma concentrations of all FAA but cystine. The lowest FAA concentrations were measured in plasma samples taken at the end of the 2-h infusion. Subsequently the level of all amino acids rose and by 24 h after the infusion the blood plasma concentration of all FAA came close to the preinfusion value. The largest differences were observed in the concentration of glutamate, glycine, leucine and isoleucine. In contrast to FAA, IRI concentration was increased significantly (almost fivefold) by VFA infusion. By 10 h after the infusion IRI concentration returned to the initial level. The results reported here indicate that energy supply given in the form of VFA infusion significantly affects blood plasma FAA profiles, supposedly as a result of changes induced in protein synthesis in tissues. Insulin presumably plays a role in the regulation of these changes.     

畜禽肉脂肪酸的营养调控研究进展

脂肪酸按饱和度可分为饱和脂肪酸(SFA)与不饱和脂肪酸(UFA)两大类,其中,不饱和脂肪酸按不饱和程度分为单不饱和脂肪酸(MUFA)和多不饱和脂肪酸(PUFA),以第一个双键出现的位置分别称为n-3族、n-6族、n-9族等多不饱和脂肪酸.     

Gastrointestinal volatile fatty acid concentrations and pH in cats

OBJECTIVE: To measure volatile fatty acid (VFA) concentrations and pH in the gastrointestinal tracts of healthy adult cats fed a commercial dry cat food. ANIMALS: 14 cats. PROCEDURE: The gastrointestinal tracts were excised immediately after euthanasia and divided into 6 sections (stomach, duodenum, jejunum, ileum, proximal portion of the colon, and distal portion of the colon). Luminal contents were collected from each segment, pH was measured, and contents were centrifuged. The supernatant was analyzed for acetate, proprionate, butyrate, isobutyrate, valerate, and isovalerate concentrations by use of gas chromatography. RESULTS: Mean total VFA concentrations were lowest in the stomach (20 mmol/L); increased through the duodenum, jejunum, and ileum (30, 29, and 41 mmol/L, respectively); and were greatest in the proximal and distal portions of the colon (109 and 131 mmol/L, respectively). Estimated mean total VFA amounts were low (<600 micromol) throughout all segments of the gastrointestinal tract; pH values increased from the stomach through the ileum and subsequently decreased in the colon. CONCLUSIONS AND CLINICAL RELEVANCE: Total VFA concentrations in the colon were comparable to values reported for the forestomach of ruminants and large intestines of monogastric animals, whereas values in the small intestine were higher than reported for other species. Total VFA amounts were low, consistent with the short, nonvoluminous gastrointestinal tract of carnivores. Luminal pH varied throughout the gastrointestinal tract in a pattern similar to other monogastric animals. Volatile fatty acids probably contribute minimal metabolic energy in cats but may be important in the maintenance of local mucosal health.     

挥发性脂肪酸和乳酸的测定方法研究

乙酸、丙酸、丁酸、戊酸、异戊酸等广泛地存在于自然界中,它们的共同特点是具有较强的挥发性,生物学上一般称之为挥发性脂肪酸(Volatile FattyAcids,VFA)。VFA在动物科学和食品科学上具有十分重要的意义,其代谢和含量是这些研究领域中常遇到的问题。因此,一个好的测定方法是研究中十分必要的。挥发性脂肪酸的测定方法有比色法、滴定法、色谱法等。相比之下,气相色谱法以快速、准确、简便,能分别测定各个组分而适用于多种样品(如:青贮饲料、瘤胃液、血液、饮料等)。但是,气相色谱法也受多种条件的影响,如色谱条件、样品的处理方法等。利…     

挥发性腊肪酸和乳酸的测定方法研究

乙酸、丙酸、丁酸、戊酸、异戊酸等广泛地存在于自然界中．它们的共同特点是具有较强的挥发性．生物学上一般称之为挥发性脂肪酸（Volatile Fatty Acids，VFA）。VFA在动物科学和食品科学上具有十分重要的意义，其代谢和含量是这些研究领域中常遇到的问题。因此，一个好的测定方法是研究中十分必要的．     

脂肪酸添加剂对奶牛瘤胃挥发性脂肪酸和甲烷的影响

21头安装瘤胃瘘管的荷斯坦产奶牛随机分为对照组和试验Ⅰ~Ⅵ组,每组3头,对照组饲喂全混日粮(TMR),试验Ⅰ~Ⅵ组每天饲喂TMR加50.0 g、100.0 g、150.0 g、200.0 g、250.0 g、300.0 g/头复合脂肪酸日粮,主要探讨复合脂肪酸对奶牛瘤胃甲烷(CH4)产量、挥发性脂肪酸(VFA)、氨氮(NH3-N)浓度和pH值及产奶性能的影响。结果,TMR中每天添加150.0~200.0 g/头复合脂肪酸,明显(P<0.05)提高奶牛乳脂率和瘤胃乙酸浓度,显著(P<0.05)降低奶牛的CH4释放量、CH4能/GE值和瘤胃NH3-N浓度,对奶牛的标准乳(FCM)、乳干物质、乳蛋白和乳糖均有提高趋势,能有效地提高奶牛的经济效益和生态效益。     

Effect of ruminal infusion of glucose, volatile fatty acids and hydrochloric acid on mineral metabolism in sheep

Two experiments were conducted to study the effects of alterations in ruminal pH and volatile fatty acid (VFA) concentrations on utilization of Mg and other minerals. In Exp. 1, two metabolism trials were conducted with 12 ruminally cannulated crossbred wethers fed 800 g/d of orchard-grass (Dactylis glomerata, L.) hay. After each feeding, wethers were ruminally infused with 500 ml (4.2 ml/min) or either 1) deionized water, 2) 40% (w/v) glucose solution, 3) .26 M propionic and .17 M butyric acid solution or 4) .35 M HCl. The pH of the VFA solution was adjusted to 6.8 with 10N NaOH. In Exp. 2, a metabolism trial was conducted with 12 ruminally cannulated crossbred wethers fed 600 g of orchard-grass hay and infused with a buffered VFA solution prepared as in Exp. 1 or with an unbuffered solution. In both experiments each trial consisted of a 5-d adaption period followed by four 5-d collections of feed, feces and urine. Compared with the glucose treatment, infusion of the buffered VFA solution produced similar acetic and propionic and higher (P less than .05) butyric acid concentrations (Exp. 1). The HCl solution produced changes in ruminal and pH values similar to those of the glucose infusion. In Exp. 1, apparent absorption of Mg was increased over twofold by the glucose infusion (P less than .05), but the other infusions had no effect. Apparent absorption of P was decreased (P less than .05) by HCl infusion, and K absorption was decreased by HCl and glucose infusions. In Exp. 2, infusion of the unbuffered VFA solution decreased apparent Mg absorption by 15.7%, compared with infusion of the buffered solution. These experiments suggest that the increased Mg absorption observed with carbohydrate supplementation is not due to alterations in ruminal pH or VFA levels.     

Measurement of volatile fatty acid production rates in sheep given roughage

Measurement of the irreversible loss rate (ILR) of acetate, propionate and butyrate by radioisotope dilution of the respective tracers in sheep offered chopped dried grass from continuous belt type feeders gave 'plateau samples', the specific radioactivity of which had unacceptably high variance (coefficient of variation [cv] of the five or six samples taken from any one animal over the last four hours of 10 hours infusion ranged from 16 to 57 per cent). In an experiment which attempted to identify the source of this variability the distribution of the liquid phase marker 51Cr EDTA into different areas of the rumen was examined during its administration either in liquid form or impregnated on paper. The paper provided better mixing but incurred considerable spillage problems which would be unacceptable where calculations of ILR were required. Radiographic observations were made to examine the mixing of radio-opaque liquid and solid phase markers in the rumen. A better mixing of both was achieved with intermittent than continuous feeding. When 1-14C- and 2-14C-labelled acetate were each infused into the rumen of four sheep given two levels of chopped dried grass by means of hourly feeders, samples of rumen liquor gave much lower variability of the mean plateau specific radioactivity values than was obtained in experiment 1 (cv less than 15 per cent in all but one sheep). The ILRs of acetate and the transfer quotients of carbon from acetate to butyrate obtained using 1-14C- and 2-14C-labelled acetate were similar.(ABSTRACT TRUNCATED AT 250 WORDS)