限制性氨基酸在养猪生产中的应用

动物对蛋白质的需要,实质上是对氨基酸的需要。氨基酸,特别是限制性氨基酸的种类,含量和配比,直接影响着日粮的营养价值和畜禽的生产性能。在动物日粮中添加限制性氨基酸,最大限度地提高饲料利用率,是近年来研究的重要课题之     

苏氨酸在畜禽营养中的研究进展

苏氨酸是百合的必需氨基酸，是畜禽日粮中的第二或第三限制性氨基酸，它在动物体内具有极其重要的生理作用，如提高饲料报酬、促进生长、增强免疫机能等；添加苏氨酸可以平衡百合日粮中的氨基酸水平，使氨基酸比例更接近于理想蛋白质模式，从而降低畜禽对饲料中蛋白含量的要求。本文就苏氨酸的理化特性、代谢途径、生理作用及其在畜禽饲料中的应用情况等研究进展进行了分析，以利于苏氨酸在畜禽生产中得到更好的应用。     

过量的氨基酸降低动物生产性能

过量的氨基酸降低动物生产性能通常氨基酸以结晶状态加入饲料。由于猪与禽的玉米──豆饼型饲料中，蛋氨酸和赖氨酸是主要的限制性氨基酸，所以它们被广泛采用，以促进动物生长，提高饲料利用率，但是，添加过量的氨基酸既增加饲料成本又可能降低猪与禽的生产性能。在美国...     

猪,禽赖氨酸的需要量

对生长的猪、禽来说,饲料中的蛋白质含量并不是越多越好,饲料中蛋白质含量过高,会使很多的氨基酸因不平衡而超过需要量。这些过剩的氨基酸不能合成体蛋白,只能作为低效的热被代谢分解排出体外,产生的代谢热,有时还会造成畜禽患应激症,影响饲料利用率和畜禽生长。为提高蛋白质的生物学效价,充分发挥氨基酸的互补作用,饲料中合理添加氨基酸,特别是限制性氨基酸制成平衡日粮,才是最科学、饲养效益最佳的饲料。我国的猪、禽饲料都是以谷类为主,赖     

苏氨酸对畜禽的营养研究进展

苏氨酸是畜禽的第二或第三限制性氨基酸，它在动物体内具有极其重要的生理作用如促进生长、提高免疫机能等；并且由于添加苏氨酸可以更好地平衡日粮氨基酸使氨基酸比例更接近于理想蛋白质从而降低畜禽对饲料中蛋白含量的要求。苏氨酸的这些使用使其在饲粮中的添加愈来愈重要。本文就苏氨酸的生理作用、合成方法、畜禽苏氨酸需要及其添加注意事项作一简单介绍。     

过度地添加氨基酸会降低生产性能

结晶氨基酸常被添加入饲料中,这是因为在玉米——大豆粉组成的基础日粮中蛋氨酸(Met)和赖氨酸(Lys)是高度限制性氨基酸。饲料中添加结晶蛋氨酸和赖氨酸可以促进动物生长,提高动物对饲料的利用率。 然而,过量地添加氨基酸会造成因添加量高或者是由于氨基酸剂量控制设备失灵而     

蚕豆复合氨基酸饲喂肉鸡试验

蛋白质资源的不足,直接影响畜禽饲养业的发展,因此开发蛋白质饲料资源,提高蛋白质利用率是极为重要的。饲料蛋白质的营养价值主要取决于氨基酸的组成。在畜禽饲料中添加一些氨基酸有助于饲料中氨基酸的平衡,从而提高饲料中蛋白质的利用率.蚕豆中提取的复合氨基酸,具有较高的营     

赖氨酸在猪禽营养中的作用

赖氨酸是动物最重要的必需氨基酸之一。因具有二个氨基，其中一个氨基连接在ε－碳原子上，故表现为碱性氨基酸并具备某些特殊性质，为猪的第一限制性氨基酸，家禽的第二限制性氨基酸。当饲料中添加足够量的赖氨酸可适当降低饲料蛋白，提高畜禽胴体瘦肉率和屠宰率；与精氨酸之间存在着拮抗作用，比例适当时畜禽能达到最佳生产性能；可利用率主要受到饲料抗营养因子和加工方式的影响。     

苏氨酸的营养研究进展

苏氨酸(Thr)是由W.C.Rose1935年从纤维蛋白水解产物中分离和鉴定出来的,因其结构类似苏糖,故将其命名为苏氨酸。苏氨酸现已证明是最后被发现的必需氨基酸,它是畜禽的第二或第三限制性氨基酸,它在动物体内具有极其重要的生理作用。如促进生长、提高免疫机能等;添加苏氨酸可以更好地平衡日粮氨基酸,使氨基酸比例更接近于理想蛋白质,从而降低畜禽对饲料中蛋白含量的要求。缺乏苏氨酸,可导致动物采食量降低、生长受阻、饲料利用率下降、免疫机能抑制等症状。近年来,Lys、Met合成品在饲料中得到了广泛应用,苏氨酸逐渐成为影响动物生产性能的限…     

猪饲料中色氨酸的利用率

氨基酸是蛋白质的结构单元、也是生猪生产的必需营养成分。在10种必需氨基酸中,一般认为赖氨酸是猪的玉米、玉米-鱼粉、玉米-肉骨粉和低蛋白玉米-大豆饼粉饲粮中的第一限制性氨基酸、色氨酸是第二限制性氨基酸。为了提高猪氨基酸需要量的准确性,还需了解饲料中氨基酸的利用率。利用率的定义是:蛋白质中某种氨基酸能用于动物生长、发育和维持的那一部分。业已报道过若干种测定饲料中氨基酸利用率     

商会自治的基石——商会自治规范研究

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。     

癸氧喹酯干混悬剂含量测定的改进

采用高效液相色谱法测定癸氧喹酯干混悬剂的含量,在2-250μg/mL范围内,峰面积的常用对数与进样量浓度的常用对数呈良好的线性关系,R^2=1(n=5),平均回收率为99.24%~99.51%,RSD在0.05%~0.28%。此方法分析时间短,样品前处理简便、定量结果准确,重现性好,结果满意,为其质量控制提供了依据。     

猪毛色遗传的研究进展

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。     

Comparison of 2 methods of centesis of the bursa of the biceps brachii tendon of horses

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.     

不同样本商品蜂蜜中硒含量的测定

用硝酸和高氯酸消化蜂蜜,使硒游离出来,在微酸性环境下,硒和2,3-二氨基萘(DAN)生成有较强荧光的物质,用环己烷萃取,在激发波长378nm,荧光波长518nm处测定其荧光强度。蜂蜜中硒含量范围:0.10～0.82μg/g。表明:蜂蜜应视为天然富硒营养品。     

乳酸杆菌益生作用机制的研究进展

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。     

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.     

Mechanism of Action of Probiotic Function of Lactobacilli

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.     

Evaluation of serum concentrations of biomarkers of skeletal metabolism and results of radiography as indicators of severity of osteochondrosis in foals

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.