降低肉鸡热应激敏感性的遗传策略

热应激是指处于高温环境下的动物机体对热环境刺激所作的非特异性生理反应的总和,它涉及神经系统、内分泌系统及免疫系统等的一系列反应.热应激对整个机体都有不同程度的影响,但对其作用机制的研究还未达到一致的观点.现代肉鸡生产养殖的特点是生长速度快、饲料吸收和代谢能力强、内部产热高,这些因素都加大了其受外部温度影响的可能性,并使其对多种代谢问题例如酸碱平衡等的敏感性和易感性增加.体外的高温环境阻碍了体内热量的散失,导致肉鸡身体温度的升高,进而影响食欲和生长速度(饲料转化率低),呈现高死亡率.基于热应激对肉鸡生产带来的影响,研究者们从营养、遗传、生理等各方面对降低热应激进行研究,在通过多种营养措施来改善热应激反应的同时,从遗传上培育耐热应激的鸡也成为研究热点之一.2011年2月14～16日,由悉尼大学家禽研究基金会和世界家禽科学协会(WPSA)澳大利亚分会联合组 织的第22届澳大利亚家禽科学年会在悉尼大学举行.大会分别对家禽营养、福利、热应激以及疾病等进行专题研讨.热应激专题中来自巴西、以色列、澳大利亚的研究者分别从生理、遗传和营养的角度对热应激 状态下电解质平衡对鸡生产性能的改善、降低肉鸡热应激敏感性的遗传方法和日粮脂肪酸改善热应激潜力的重新评估进行探讨.本专题对以上三个报告进行刊登,供读者参考.     

电解质平衡对热应激状态下鸡生产性能的改善

热应激是指处于高温环境下的动物机体对热环境刺激所作的非特异性生理反应的总和,它涉及神经系统、内分泌系统及免疫系统等的一系列反应.热应激对整个机体都有不同程度的影响,但对其作用机制的研究还未达到一致的观点.现代肉鸡生产养殖的特点是生长速度快、饲料吸收和代谢能力强、内部产热高,这些因素都加大了其受外部温度影响的可能性,并使其对多种代谢问题例如酸碱平衡等的敏感性和易感性增加.体外的高温环境阻碍了体内热量的散失,导致肉鸡身体温度的升高,进而影响食欲和生长速度(饲料转化率低),呈现高死亡率.基于热应激对肉鸡生产带来的影响,研究者们从营养、遗传、生理等各方面对降低热应激进行研究,在通过多种营养措施来改善热应激反应的同时,从遗传上培育耐热应激的鸡也成为研究热点之一.2011年2月14～16日,由悉尼大学家禽研究基金会和世界家禽科学协会(WPSA)澳大利亚分会联合组 织的第22届澳大利亚家禽科学年会在悉尼大学举行.大会分别对家禽营养、福利、热应激以及疾病等进行专题研讨.热应激专题中来自巴西、以色列、澳大利亚的研究者分别从生理、遗传和营养的角度对热应激 状态下电解质平衡对鸡生产性能的改善、降低肉鸡热应激敏感性的遗传方法和日粮脂肪酸改善热应激潜力的重新评估进行探讨.本专题对以上三个报告进行刊登,供读者参考.     

热应激对肉鸡生产性能的影响

随着遗传育种的改良和高效营养技术的发展,环境因素对家禽生产的影响愈发突出。在众多环境因子中,高温环境是影响家禽生产的一个重要因素,尤其是位于热带、亚热带的华南地区。肉鸡由于被羽较厚,汗腺缺乏,代谢旺盛,对高温环境极为敏感,在生产中易出现热应激。热应激会显著影响肉鸡的生长、代谢、肉品质以及生理机能,给肉鸡养殖业造成经济损失。本文综述了热应激对肉鸡采食行为、脂肪沉积、肉品质和血液指标影响的研究进展,以期为肉鸡热应激的防控提供参考。     

蛋鸡抗热应激添加剂的研究

在影响蛋鸡生产性能的诸多因素中,环境温度最为突出。产蛋鸡的适宜环境温度为13～20℃,气温高于这个上限,蛋鸡就会发生热应激而影响生产性能。热应激是机体热应源的非特异性防御应答的生理反应,以保持机体在极端条件下的代谢平衡。由于鸡体温高、代谢旺盛、皮肤不具有汗腺等生理特点,高温能导致鸡体内代谢和生理机能的改变,降低蛋鸡的产蛋率和饲料报酬等,给生产带来严重损失。现有的一些减轻家禽热应激的措施有改善与控制鸡舍环境、加强饲养管理、调整日粮营养浓度、使用     

中草药添加剂对蛋鸡热应激的影响

鸡的耐热能力差,极易发生热应激.高温可导致代谢和生理机能改变,降低蛋鸡的产蛋率和饲料报酬等,给生产带来严重的经济损失.目前,提出和采用的一些减轻家禽热应激的措施有控制鸡舍内的温度、加强饲养管理、调整日粮营养、使用抗应激添加剂、增强机体适应和抵抗高温的能力等.中草药含有维生素、矿物质、氨基酸和微量元素等营养物质,来源广泛,使用方便,日益受到重视.试验主要从机体内环境考虑,选用来源广、价格低的中草药并按一定比例组方,研究在高温季节其对蛋鸡生产性能的影响.     

热应激条件下蛋鸡的营养调控措旆

热应激通常是指动物机体处于高温环境中所产生的一系列非特异性应答反应的总和。家禽具有体温高、代谢旺盛、无汗腺、羽毛厚不易散热等特点，对高温环境反应较敏感且耐受力差。因此在高温环境下容易发生热应激。一般认为，产蛋鸡适宜温度为13-27℃，当环境温度高于32℃时，就会使鸡．处于应激状态，引起鸡生理及精神上的一系列不良反应。成年家禽常表现为难以维持正常体温，当环境温度高于37℃时，其生理功能趋于紊乱。热应激状态影响鸡采食和营养物质的吸收代谢，进而影响鸡的健康和生产性能，甚至导致发病或死亡，大大减少了养殖者的经济效益。日粮中营养物质含量影响鸡的产热和热应激时的生理状况，因此，在做好防暑降温工作的同时调整日粮中营养物质的供给是缓解热应激的重要途径之一。所以，应针对热应激状态下的营养需要．适当调罄饲料配方．以便更有效地缓解热应激。     

家禽的热应激及其综合调控

家禽生产的集约化程度日益提高，夏天高温造成的热应激对家禽生产的影响越来越严重。热应激不仅使蛋鸡产蛋率下降，蛋重减少，破蛋率增加，种蛋受精率和孵化率降低，肉鸡生长速度变慢，而且会导致鸡的抵抗力和免疫力下降甚至大批死亡，给养禽业造成巨大的经济损失。因而缓解热应激对家禽的影响具有重要的意义。 　　所谓热应激，就是家禽对于其生理不利的热环境产生的非特异性应答反应总和。它通过改变鸡的各种生理、生化反应，从而降低鸡的采食量、生产性能、饲料效率及产品质量。根据家禽的反应，环境温度可分为温度适中区、热应激区和冷…     

益生菌可有效缓解高温季热应激对鸡的负面影响

夏季高温季节热应激能降低鸡采食量,影响机体对营养的吸收利用效率,破坏肠道正常结构和免疫功能,从而影响鸡的健康和生产性能。目前,解决热应激的方法主要有控制环境温度,饲喂高能量饲料,在饲料中添加电解质和抗氧化维生素。近年来,益生元、益生菌和合生元也被越来越多地用于减轻热应激造成的负面影响。益生菌可以改善高温环境下鸡肠道的微生态系统和肠道形态、生理机能、免疫系统和生长发育,成为缓解鸡热应激造成损害的首要选择。     

热应激对产蛋鸡的影响及防治措施

高温通过改变鸡的各种生理影响鸡的采食量,降低饲料效率及其产品质量,影响鸡的生产性能,重者可导致鸡只的死亡,给养鸡业生产带来严重的损失.因此,了解热应缴对家禽的影响,以及热应激的控制措施对广大从事养鸡生产者来说是十分重要的也是十分必要的.通过药物性添加剂,改善畜舍环境卫生,合理饲养管理等措施可有效减缓并防治家禽热应激.     

鸡饲料中添加维生素的效果

尽管各种维生素对家禽作用的研究不少,但某些家禽对维生素的需要量还不十分清楚,尤其象火鸡的种鸡等特种家禽。现在鸡的维生素需要量是很早以前研究的数据,几十年来,鸡的生产性能、饲养管理水平等已发生很大的变化,这些需要量是否符合当前生产实际,值得探索。鸡除了正常的维生素需要量外,还与饲养环境、代谢等因子有关。 1.环境与维生素 (1)热应激 在气候炎热地区,高温常常给鸡造成热应激,为了缓解热应激,除了改善饲养管理条件外,主要对策还是加强饲料的营养,而维生素是重要的一环。     

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.