畜禽的应激反应

<正> 畜禽应激的原因很多,如环境、饲养管理等。自然环境的应激,人们只能预防而不能使其消除。饲养管理上的应激是人们可以控制和消除的。现在繁多的应激原中,着重谈几种对畜禽生产性能影响较严重的,又难以控制的应激因素。与应激有关的系统的变化,详见图1。     

试论应激对家禽养殖的危害与防控要点

应激在家禽养殖过程中无处不在,严重影响了家禽生产性能的提高,给我国养禽业造成了较大的经济损失,日益引起人们的重视。本文对应激概念、应激分类、应激对家禽的影响进行了系统阐述,提出了相对的防控措施,以期为家禽健康养殖提供参考。     

热应激对家禽的影响

<正>应激是机体受到强烈应激源刺激所引发的全身性非特异性反应,引起应激的因素很多,其中高温是引起应激的一种主要的环境因素,我国是养禽大国,夏季高温是制约着我国养禽业发展的一个主要因素,尤其是这几十年来人们过分追求肉鸡的生     

高温热应激对家禽的影响

应激是机体受到强烈应激源刺激所引发的全身性非特异性反应,引起应激的因素很多,其中高温是引起应激的一种主要的环境因素。我国是养禽大国,夏季高温是制约着我国养禽业发展的一个主要因素,尤其是这几十年来人们过分追求肉鸡的生长速度与蛋鸡的产蛋量,违背了家禽本身的生     

谈工作犬训练中的应激因素

正动物应激对动物的生长发育、疾病防疫和性能培育具有重大影响。通过研究应激的内涵,可判断犬应激阶段的能力;分析工作犬训练的手段和环境中的应激因子,有助于了解和掌握训练中出现的问题。一、动物应激的概念及应激的三个阶段对于工作犬训练的影响(一)应激的概念在工作犬训练中的应用应激是动物对一切胁迫性刺激进行自身适应性反应的总称。从某种意义上说,对工作犬进行训练是犬由应激—缓解—再应激—再缓解的过程。经过这个过程,使工作犬对某些刺激形成条件反射进而加以利用。(二)对工作犬训练与健康的负作用     

维生素对家禽的作用

迄今,有关维生素对家禽的作用已有很多研究。但对某些禽类(例如种火鸡)的研究目前还很有限。另外,随着家禽育种工作的进展,以前的维生素需要量数值对于新的家禽品系也未必适合。一、环境因素和维生素需要量1.热应激高温环境会使鸡产生严重的热应激。缓解热应激的措施除改善饲养管理外,加强饲料营养也是不可缺少的方法。尤其是维生素的强     

家禽的应激及其研究进展

对动物应激进行研究,其重要性在于:引起应激的因素很多,几乎涉及动物生产的每一个环节:应激对动物所产生的效应是广泛的,几乎涉及动物的每一个系统:应激所引起的症状往往是亚临床的,容易被忽视,然而其影响是巨大的;应激的有利方面常常因其有害方面而被忽视.本文对应激的定义、机制、利弊、量化、影响因素和对策进行综述,期望能够抛砖引玉,对未来的应激研究有所启迪.     

热应激对鸡免疫功能的影响

1热应激的概念应激(stress)是动物对不良因素或应激原(stressor)刺激的应答。热应激是指动物机体对热应激原的非特异性防御应答的生理反应。鸡是恒温动物，不同类、年龄鸡理想的温度范围问题上存在着很多争议，这是因为很多因素影响鸡对温度变化的反应，如空气湿度、风速、鸡以前所处的温度环境及时间等是重要的因素。当环境温度超过其等温区中的舒适区上限值时，鸡就会出现热应激。热应激不仅可影响鸡的正常生理功能，而且对鸡的免疫功能及所用疫苗发挥正常的免疫作用产生影响，这将会成为多种疾病的诱因，因此，热应激影响鸡免疫功能的研…     

肠道——畜禽热应激研究中被忽视的核心环节

长期以来,人们对热应激机理的研究着重于中枢神经系统,许多研究和现象却提示人们,被忽视的肠道极有可能是引起热应激的核心环节。本文综述了热应激机理研究的新进展即热应激导致肠道损伤接着内毒素侵入是引起畜禽一系列热应激症状的最主要原因,这为畜禽的热应激机理研究提供了新的思路,具有非常重要的意义。     

家禽应激与免疫的交互作用

应激的概念个体对周围环境的适应能力是群体历史过程中的选择作用加上个体生活过程中所进行的调节作用。在讨论应激的概念时,Selye强调区分应激和产生应激的因子(应激物)的重要性,并把应激的定义规定为“机体对向它提出的任何要求所作的非特异性应答”。在这个意义上,应激性刺激(即应激物)包括生存所必需的常规发生的事物。实际上,应激可看成是对这些要求的健康应答。     

肉鸡腹水症发病机理的研究Ⅲ.低温对肉鸡心功能和心室结构的影响

本研究采用心电图描记技术动态检测低温环境下肉鸡右心功能的变化，同时利用电镜技术观察心肌超微结构的病理变化。研究表明低温处理1周后心电图Ⅱ导联、AVF导联S波幅显著升高，主要呈rS波型;超微结构显示肌原纤维部分断裂、线粒体体积增大为特征；而右 心室病变较轻。低温处理3周、4周后左右心室肌微丝受损, 肌原纤维Z线模糊或消失,线粒体明显肿胀,严重者出现空泡样变，左心室的病理变化比右心室重。研究发现低温处理后肉鸡 右心功能减退，左右心室病理组织学变化有所不同，提示低温处理后肉鸡早期左心主要呈 代偿性变化，中期右心出现代偿功能变化，左心代偿功能增强，而后期左心室出现失代偿的 病变，左心室病变可能对肉鸡腹水症的形成有直接影响。     

Usefulness of dobutamine stress tests for detection of cardiac abnormalities in dogs with experimentally induced early left ventricular dysfunction

OBJECTIVE: To determine whether dobutamine stress tests (DST) can be used to detect cardiac dysfunction in dogs with early left ventricular dysfunction (ELVD) induced by rapid right ventricular pacing (RRVP). ANIMALS: 7 adult male Beagles. PROCEDURE: A pacemaker was surgically implanted in each dog at the level of the right ventricular apex. Electrocardiography, Doppler sphygmomanometry, and Doppler echocardiography were performed before and during a DST prior to activation of the pacemaker and every 3 to 4 days during the period of RRVP. Dobutamine stress tests were performed by infusing dobutamine at incremental dosages ranging from 12.5 to 42.5 microg/kg of body weight/min. RESULTS: Clinical signs of congestive heart failure were not observed during the pacing period. However, all dogs developed ELVD associated with significant changes in values for most Doppler echocardiographic variables obtained prior to DST Adverse cardiac effects were not detected during DST. Most Doppler echocardiographic indices of cardiac function were significantly altered in response to dobutamine infusion during the pacing period, compared with prepacing values. However, a dobutamine-induced 2-fold increase in cardiac output was maintained. CONCLUSIONS AND CLINICAL RELEVANCE: Dobutamine stress tests can be safely performed in dogs with experimentally induced ELVD. Dobutamine stress tests may be a sensitive, noninvasive diagnostic method, complementary to standard clinical examinations, for detection of early cardiac dysfunction in dogs asymptomatic for dilated cardiomyopathy.     

Effects of clustered drill holes on the breaking strength of the equine third metacarpal bone

The breaking strength (stress at failure) of equine third metacarpal bones, with and without clustered drill holes, was determined in vitro. Paired ossa metacarpalia II-IV of 39 horses (n = 39) between 2 and 7 years old were tested in palmarodorsal 3-point bending. Four treatments were compared. Clustered 2.7- or 3.5-mm drill holes, in a 4- or 7-hole pattern, were made in the dorsal cortex of the distal diaphysis of the left third metacarpal bone. Undrilled right third metacarpi were used as controls. Bones with clustered drill holes failed by an oblique fracture through 1 or more drill holes, whereas undrilled bones failed with a middiaphyseal transverse fracture. Clustered drill holes acted as a stress concentrator and significantly (P less than 0.05) decreased the stress required for failure. However, differences in breaking strength between treatment groups were not significant (P greater than 0.05).     

不同耐热性中国荷斯坦奶牛产奶量差异分析

本研究通过评定热应激条件下奶牛呼吸评分和流涎指数，将中国荷斯坦泌乳奶牛划分为热应激耐受组（2 271头）和热应激易感组（2 024头），利用固定效应模型和混合效应模型考虑场、胎次和泌乳阶段等因素，比较热应激期奶牛直肠温度差异及奶牛在不同时期的产奶性能差异。结果表明，热应激耐受组奶牛直肠温度显著低于热应激易感组（P<0.05）；在非热应激期（5月），热应激耐受奶牛与热应激易感奶牛的平均日产奶量接近，热应激耐受奶牛的较低（低0.68 kg），但差异不显著（P>0.05）；在热应激期（7~8月），两组奶牛产奶量均有下降，热应激耐受组奶牛平均日产奶量下降幅度（与5月相比）低于热应激易感组，尤其是在热应激最严重的8月（下降幅度分别为18.06%与23.01%）。以上试验结果表明，热应激环境下通过呼吸评分与流涎指数可有效判断奶牛的耐热性。本试验结果可为奶牛热应激反应评价及奶牛养殖过程中通过量化奶牛热应激反应，及时采取措施降低热应激的损失提供一定理论依据。     

Relieving veterinarians' workloads and stress: leveraging Australia's veterinary technologists and nurses

Like the rest of the world, Australia is in the throes of a dire shortage of veterinarians, while the demand for veterinary professional services grows. This combination has a very real impact on veterinarians' workload and stress, with significant mental health impacts. Times have changed in our profession and it is time for a change in our practice. We need to look at a different way of managing veterinary workloads and demands and, in particular, better utilise our paraprofessional staff. It is the solution right under our noses embracing our veterinary technologists and nurses.     

Evaluation of vectorelectrocardiographic analysis of young broiler chickens as a predictive index for susceptibility to ascites syndrome.

Vectorelectrocardiographic (VCG) analysis was performed on 50 male broiler chicks (1 week of age) before placement in a hypobaric chamber. During 5 weeks of exposure to hypobaric hypoxia (simulated altitude of 2900 m), all recorded mortality (38%) was due to the development of ascites syndrome. There was a positive correlation (r = 0.74, P less than 0.01) between the increment in the frontal plane mean resultant vector magnitude divided by body weight (designated as the cardiac index [CI]), with the severity of right ventricular enlargement. Chicks developing ascites syndrome had a greater CI (P less than 0.05) at 1 week of age when compared with chicks that did not develop the syndrome. Therefore, the CI calculated by VCG analysis recognizes right ventricular enlargement, suggesting that a pre-hatch or early post-hatch functional cardiac stress has occurred, predisposing the 1-week-old broiler chick to ascites syndrome. Application of the CI has a physiological index may prove useful in future studies targeted for selection of ascites syndrome resistance in broiler chickens.     

野生双峰驼下颌骨的三维重建与应力分析

通过对5个野双峰驼(Camelus bactrianus ferus)下颌骨进行螺旋CT扫描,利用软件Amira 3.1.1对CT扫描图三维重建得到下颌骨三维点云图,并利用Geomagic软件进行实体化,通过有限元分析软件Ansys 14.0对野双峰驼下颌骨角部施加1000 N大小的力后对下颌骨进行有限元分析,得到下颌骨在受力时的应力分布情况:当左下颌角受到水平向右垂直于矢状面的外力时,左下颌角及髁状突颈部极易造成骨折,左颏孔区可能会出现骨裂,而其余部分仅会造成轻微损伤。当右下颌角下缘受到垂直向上垂直于矢状面的外力时,也易出现同样的结果。由此得出结论:当野双峰驼下颌骨角部受到瞬间外力时,应力主要集中在施加力所在骨支的薄弱区域,应力较大部位与骨折易发部位密切相关;且在薄弱区域,下颌角及髁状突颈部的损害最为严重。以上结果有利于深入了解野双峰驼下颌骨应力分布情况,并为骨三维重建在生物学领域的应用提供理论依据。     

An association between complete and incomplete stress fractures of the humerus in racehorses.

Twenty-one horses had a complete unilateral humeral fracture during race training or racing at a California racetrack during the period 24 February 1990 to 10 July 1991. Fractures occurred approximately equally in left and right limbs, and in males and females. Most fractures occurred during training, and in 2- and 3-year-old horses. Only 5 of 16 Thoroughbred horses with known racing records had previously raced more than once, and their mean time between races was less than the time between their last race and fracture (P = 0.07). Ten of 13 humeri studied further had gross evidence of periosteal callus bridging one portion of the fracture line, indicative of a pre-existing stress fracture.     

断奶对仔猪肠道屏障的影响及营养调控

在集约化养殖中,3~4周龄早期断奶是仔猪生命周期中一个非常紧张的时期,此时仔猪胃肠道还未发育成熟。肠道屏障由上皮、免疫和肠神经系统组成,这些系统控制上皮屏障的完整性以及肠道功能,包括肠腔营养物质、水和电解质的运输。早期断奶导致肠道通透性增加,出现胃肠功能紊乱的情况,可能对猪只一生产生长期的影响。因此,仔猪断奶饲粮需要正确水平的营养素、营养源和高质量的添加剂,鼓励仔猪快速进食,减轻或消除断奶应激综合症,降低死亡率和发病率。养猪就是养"肠道",合理使用功能性氨基酸、植物化学物质和有机酸等添加剂,能够修复由于断奶应激综合症导致的肠道屏障功能障碍。     

Physiological responses to treadmill exercise and ambient temperature in normal and malignant hyperthermia susceptible pigs.

Ten susceptible and ten resistant pigs to malignant hyperthermia were used to observe the effects of exercise and ambient temperature on selected physiological parameters. Pigs were submitted to a ten minute exercise on a treadmill operating at a speed of 1.8 km/h and inclined to 11 degrees. Exercise in the first group was at an ambient temperature of 14 degrees C, and in the second at 29 degrees C. The right carotid artery was previously cannulated for blood pressure measurements and for repeated blood sampling during exercise. Arterial pressure, heart rate, rectal and cutaneous temperatures were recorded. Levels of cortisol, creatine kinase and its isoenzymes were measured. At 14 degrees C, exercise caused some physiological adjustments in susceptible animals; heart rate, skin temperature and cortisol levels increased (P less than 0.05). In resistant pigs, only the heart rate was elevated significantly following exertional stress at 14 degrees C. Exercise at 29 degrees C produced severe stress and marked physiological changes: heart rate, rectal and skin temperatures and cortisol levels increased significantly in both susceptible and resistant swine. At 29 degrees C, susceptible pigs also had higher levels of serum cortisol, total creatine kinase and MM isoenzyme (P less than 0.05) compared to resistant pigs. The results indicate that, following exertional or thermal stress, susceptible pigs undergo more extensive physiological changes than do resistant pigs. Similar levels of stress prior to slaughter may trigger physiological changes which in the susceptible pigs would likely result in pale, soft exudative myopathy.