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詹海琴 《畜牧兽医科技信息》2015,(4):7-8
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。 相似文献
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小肽是蛋白质降解为氨基酸过程中的中间产物,是动物蛋白质营养中的重要物质;小肽的吸收部位除小肠外,还有瘤胃、瓣胃等;小肽的转运机制与氨基酸明显不同;小肽吸收具有耗能低、速度快、载体不易饱和等优点,小肽吸收具有降低游离氨基酸间的吸收竞争、促进氨基酸(除蛋氨酸外)的吸收等作用;小肽还能促进蛋白质的合成和矿物质元素的吸收代谢。蛋白质的种类、消化酶的活性、小肽本身的性质都会影响小肽的释放、吸收及代谢。 相似文献
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绿色饲料添加剂-生物活性肽 总被引：8，自引：0，他引：8
传统观点认为蛋白质营养实质上是氨基酸营养,蛋白质必须被消化成为游离氨基酸之后才可被吸收利用。但最近研究表明,以氨基酸代替粗蛋白的量是有限的,直接吸收较大分子的肽也是非常重要和必要的,因此,添加合成氨基酸很难获得最佳的生长效果。肽与氨基酸的吸收,存在两种独立的转运机制。小肽吸收具有转运快,耗能低、不易饱和等特点;而氨基酸则吸收慢、耗能高、载体易饱和,从而限制了其在肠道中的吸收量。目前普遍认为,动物从胃肠部位吸收二肽或三肽是一种重要的生理现象,且循环中相当数量的氨基酸是以寡肽形式被吸收的,因此,肽营 相似文献
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蛋白质在动物营养中起着重要作用,大量研究已表明蛋白质营养不仅是游离氨基酸营养,肽营养也具有重要作用。本文综述了反刍动物肽的吸收特点及影响因素,肽的吸收代谢机制,肽对瘤胃微生物的调控及对反刍动物生产性能发挥的作用,并阐述饲料蛋白源活性肽的开发应用及肽营养研究与应用前景。 相似文献
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小肽转运蛋白(PepT1)基因研究进展 总被引：9，自引：0，他引：9
小肽作为蛋白质的主要消化产物 ,在氨基酸消化、吸收和代谢中起着重要作用。小肽与游离氨基酸的吸收是两个相互独立的转运系统 ,与游离氨基酸相比 ,小肽具有吸收速度快、耗能低、不易饱和 ,且各种肽之间转运无竞争性与抑制性等特点。本文主要综述了小肽转运机制的特点和小肽转运蛋白(PepT1)分子生物学方面的研究进展 ,包括PepT1分子结构特点 ,PepT1cDNA的克隆 ,不同动物之间PepT1氨基酸序列的同源性 ,PepT1mRNA在不同动物、不同组织中的分布 ,以及营养水平对PepT1基因表达的影响 ;并就需要进一步深入研究的问题进行了探讨 相似文献
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小肽吸收机制研究进展 总被引：3，自引：0，他引：3
小肽作为蛋白质的消化产物,在氨基酸的消化、吸收和代谢中起着重要作用。小肽与游离氨基酸的吸收是两个相互独立的转运系统,与游离氨基酸相比,小肽具有吸收速度快、耗能低、不易饱和,且各种肽之间转运无竞争性与抑制性等特点。本文综述了小肽在单胃和反刍动物体内的转运机制的特点,介绍了小肽转运载体(Peptidestransporter)分子生物学特性和其转运肽的过程.分析了对小肽吸收的影响因素。 相似文献
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小肽(Small peptide)是蛋白质在动物消化道内消化成氨基酸的中间产物,小肽能被动物直接吸收的肽营养理论是营养学上的一个重要发现,其对动物的营养作用不容忽视.文章阐述小肽吸收机制及营养作用,同时对肽营养研究作出展望. 相似文献
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魏静 《四川畜牧兽医学院学报》2009,(4):28-32
在现代法律秩序中,商会自治规范是制定法的基础和必要的补充,甚至在某些方面替代了制定法;商会自治规范主要包括商会组织规范、行为规范、惩罚规范以及争端解决规范等;其效力仅及于其内部成员;商会自治规范和制定法之间存在冲突,但也存在整合的基础。 相似文献
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本文概述了猪的毛色类型、猪的毛色遗传模式,着重综述了猪毛色基因分子基础的研究进展,指出存在问题并就未来发展方向做了思考。 相似文献
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REASONS FOR PERFORMING STUDY: Centesis of the bicipital bursa using an 8.9 cm long spinal needle has been reported but the alternative of employing a 3.8 cm long hypodermic needle requires validation. OBJECTIVE: To compare the efficacy of 2 different methods of centesis of the bicipital bursa and to evaluate the usefulness of ultrasonographic imaging to determine the location of solution administered when centesis of the bursa is attempted. METHODS: For Trial 1, 6 clinicians, who had no previous experience of centesis of the bicipital bursa, attempted to inject a solution composed of an aqueous radiopaque contrast medium and physiological saline solution (PSS) into the bicipital bursae of 2/12 horses using the previously described distal approach to inject one bursa and a proximal approach to inject the contralateral bursa. The bicipital tendon and bursa were examined ultrasonographically before and after injection; and both shoulders were examined radiographically to identify the location of the medium. In Trial 2, another 6 clinicians, also with no previous experience of centesis, repeated Trial 1, using 6 horses, but the radiopaque contrast medium was mixed with air instead of PSS. RESULTS: Accuracy of centesis using the proximal approach was 39% and that of the distal approach 28%. Ultrasonographic examination of the shoulder allowed the location of solution and air to be accurately predicted in all 12 shoulders examined. CONCLUSIONS: Clinicians who have had no previous experience performing centesis of the bicipital bursa are unlikely to be successful in centesis using either approach. Radiographic examination after injecting a radiopaque contrast medium may be necessary to assess the success of centesis especially if bursal fluid is not obtained during centesis. Injecting air along with the radiopaque contrast medium provides more accurate ultrasonographic confirmation of centesis and better radiographic definition than does injection without air. 相似文献
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Effects of size of ingestively masticated fragments of plant tissues on kinetics of digestion of NDF
Ingestively masticated fragments were collected and sized via sieving. Different sizes of esophageal masticate and ruminal digesta fragments, and ground fragments of larger masticated pieces were incubated in vitro, and undigested NDF remaining at intervals of up to 168 h of incubation was determined. The ruminal age-dependent time delay (tau) for onset of digestion of NDF was positively correlated (P < 0.004) with the mean sieve aperture estimated to retain 50% of the fragments between successive sieve apertures (MRA). Degradation rate of potentially degradable NDF (PDF) and level of indigestible NDF were not related (P > 0.10) to MRA of masticated and ground fragments. Estimates of tau were positively related to MRA, with slopes of bermudagrass < corn silage < ruminal fragments of corn silage. It was concluded that fragment size-, and consequently, ruminal age-dependent onset of PDF degradation of a mixture of different fragment sizes results in an age-dependent rate of degradation of the more rapidly degrading of two subentities of PDF. Models are proposed that assume a tau before onset of simultaneous degradation of PDF from two pools characterized as having gamma-modeled age-dependency and age-constant rates. The ruminal age-dependent pool seems to be associated with the faster-degrading pool, and its rate parameter increases with range in MRA in the population of fragments. Conceptually, the ruminal age-dependent rate parameter for PDF degradation seems to represent a composite of several effects: 1) effects of the size-dependent tau; 2) range in MRA of the population of ingestively masticated fragments; and 3) subentities of PDF that degrade via more rapid age-dependent rates compared with subentities of PDF that degrade via age-constant rates. The estimated fractional rates of ruminative comminution of ingestively masticated fragments (0.060 to 0.075/h) were of a magnitude similar to the mean fractional rates of PDF digestion (0.030 to 0.085/h), which implies that ruminative comminution may be first-limiting to fractional rate of PDF digestion. The in vivo roles of ingestive and ruminative mastication of fragments on PDF degradation must be considered in any kinetic system for estimating PDF digestion in the rumen. These results and others in the literature suggest that the rate of surface area exposure rather than intrinsic chemical attributes of PDF may be first-limiting to degradation rate of PDF in vivo. 相似文献
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乳酸杆菌作为益生菌广泛用于人和动物.本文综述了乳酸杆菌改善宿主健康的机制.乳酸杆菌可通过产生抗菌物质如乳酸、过氧化氢、细菌素,或者通过竞争营养或肠道黏附位点来抑制致病菌;通过诱导黏附素的分泌或阻止细胞凋亡而增强肠道的屏障功能,从而保护肠道.文章重点讨论了乳酸杆菌表面成分(表面蛋白、脂磷壁酸和肽聚糖)与肠道受体(C型凝集素受体、Toll样受体和Nod样受体),阐述了他们结合后启动免疫调节信号,调控肠道免疫功能以发挥改善健康作用的机制. 相似文献
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Billinghurst RC Brama PA van Weeren PR Knowlton MS McIlwraith CW 《American journal of veterinary research》2004,65(2):143-150
OBJECTIVE: To determine whether serum concentrations of biomarkers of skeletal metabolism can, in conjunction with radiographic evaluation, indicate severity of osteochondrosis in developing horses. ANIMALS: 43 Dutch Warmblood foals with varying severity of osteochondrosis. PROCEDURE: 24 foals were monitored for 5 months and 19 foals were monitored for 11 months. Monthly radiographs of femoropatellar-femorotibial and tibio-tarsal joints were graded for osteochondral abnormalities. Serial blood samples were assayed for 8 cartilage and bone biomarkers. At the end of the monitoring period, foals were examined for macroscopic osteochondrosis lesions. RESULTS: Temporal relationships were evident between certain serum biomarkers and osteochondrosis severity in foals during their first year. Biomarkers of collagen degradation (collagenase-generated neoepitopes of type-II collagen fragments, type-I and -II collagen fragments [COL2-3/4C(short)], and cross-linked telopeptide fragments of type-I collagen) and bone mineralization (osteocalcin) were positive indicators of osteochondrosis severity at 5 months of age. In foals with lesions at 11 months of age, osteochondrosis severity correlated negatively with COL2-3/4C(short) and osteocalcin and positively with C-propeptide of type-II procollagen (CPII), a collagen synthesis marker. Radiographic grading of osteochondrosis lesions significantly correlated with macroscopic osteochondrosis severity score at both ages and was strongest when combined with osteocalcin at 5 months and CPII at 11 months. CONCLUSIONS AND CLINICAL RELEVANCE: The ability of serum biomarkers to indicate osteochondrosis severity appears to depend on stage of disease and is strengthened with radiography. In older foals with more permanent lesions, osteochondrosis severity is significantly related to biomarker concentrations of decreased bone formation and increased cartilage synthesis. 相似文献