共查询到20条相似文献,搜索用时 343 毫秒
1.
环境对家禽免疫功能的影响 总被引:2,自引:0,他引:2
温度、光照,空气、饲料、饮水污染等对家禽免疫功能和免疫效果有直接作用。1温度对禽免疫功能的影响适宜的环境温度有利于禽的生长发育和免疫功能的正常发挥,环境温度过高或过低都会影响禽的免疫应答力。早在1956年Garren就提出过高和过低环境温度都会造成免疫抑制。在高温和低温环境中的雏鸡,淋巴组织退化,血液淋巴细胞减少。高温环境中饲养的鸡,各免疫器官发生萎缩性变,甚至坏死性变。热应激时间过长,鸡免疫器官发育受到影响,胸腺、法氏囊和脾脏重量减轻,胸腺、法氏囊等器官萎缩。1.1对体液免疫的影响在高温的反复作用下,皮质酮水平增高… 相似文献
2.
余德谦 《广东畜牧兽医科技》2001,26(4):16-17
免疫是家禽机体的一种特异性生理反应 ,通过识别和排除抗原性异物维持机体内外环境的稳定。家禽在其生长发育和生产过程中 ,必然会受到多种应激原刺激 ,这些应激因素不仅影响家禽的生长、发育、生存及生产性能 ,而且对家禽的免疫机能也会产生一定的影响 ,其影响程度因应激原的作用强度、持续刺激时间及性质而异 ,同时也与家禽的品种有关。常见的应激原有温度、光照、营养、环境、疾病等。1 温度家禽对环境温度有较强的依赖性 ,适宜的温度环境有利于家禽的生长发育和发挥正常的免疫机能。过高或过低的环境温度不仅影响家禽的生长发育和生产… 相似文献
3.
4.
(续上期)(2)寒冷对家禽细胞免疫功能影响的报道还很少,在寒冷应激时对家禽细胞免疫功能的影响究竟是加强,还是减弱,还有待进一步研究。但在家畜和小哺乳动物中,众所周知寒冷可使机体抵抗力降低,使细胞免疫功能下降。Moore等发现,小鸡在环境温度偏低时易导致白痢杆菌病的发生;Scholes也发现小鸡在寒冷环境中体温会有所降低,并认为这与沙门氏杆菌感染有直接关系;Thaxton发现体温降低会大大增加鸡副伤寒的死亡率;Turnbull认为寒冷应激会减少或延迟沙门氏杆菌对肠道粘膜上的异嗜白细胞的刺激,不能较好地建立起免疫保护,从而加… 相似文献
5.
6.
除了良好的管理措施,战胜疾病的两种途径就是治疗和预防。预防家禽疫病的措施之一就是使用疫苗对付特定的疾病。疫苗通过产生免疫力使家禽得到生物学抗病力。几十年以来,尽管免疫接种,但仍有疾病爆发流行,例如几年前因爆发法氏囊病造成大批鸡只死亡。原因可能是疫苗没有产生足够的免疫力。那么为川么会发生免疫失败?为什么疫苗{能保护家禽呢?其实影响疫苗免疫效果,造成免疫失败的因素有许多。-.疫苗因素疫苗有一定的有效期,过期的疫苗不能使用,这过w为它不能产生理想的免疫人。川W八疫苗的存放和运输过流…油公高于4ap,那么疫… 相似文献
7.
8.
鸡日粮营养水平与免疫机能 总被引:1,自引:0,他引:1
营养,不仅是维持家禽健康生长和良好生产力的基础,而且对于维持家禽免疫系统的正常机能也具有重要的意义。本文就近年来有关日粮营养水平与鸡免疫功能的关系作一综述。1家禽的免疫系统和应答反应在长期的进化过程中,家禽形成了一套与体内外“敌人”作斗争的防御系统,包括非特异防御系统,有外部屏障(皮肤和黏膜),内部屏障(血脑屏障、血胎屏障),体内的正常菌群和特异性免疫应答(体液免疫、细胞免疫)。家禽具备完成此防御功能的免疫器官:中枢免疫器官(骨髓、法氏囊、胸腺),外周免疫器官(脾脏、盲肠扁桃体)。当感染性或非感… 相似文献
9.
有关外界因素对家禽免疫功能影响的研究,始于1936年加拿大病理学家Hansseyle博士在Nature上发表关于应激学说的文章,他认为温度、饲料成分、饲养制度的改变、神经刺激和有害气体等许多完全不同的致病因子,在机体特异反应中均有相同或相似的非特异反应。随着研究的进一步深入,人们逐渐认识到,家禽的正常生长、繁殖和抵御外来病原侵袭等各种活动都必须在相对稳定的生态环境中进行。但是,随着集约化高密度饲养方式的发展,家禽在其生长发育和生产的过程中,必然会受到环境和管理中的各种不利因素(应激源)的刺激,即机体内平衡被打破,引起了应激反… 相似文献
10.
11.
12.
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
13.
14.
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
15.
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
16.
17.
18.
19.
以国际标准强毒R株人工感染非免疫产蛋鸡,定时扑杀,分别从鼻窦、眶下孔、气管、肺、气囊、卵巢和输卵管分离MG,并收集感染鸡所产蛋分离MG。结果表明,人工感染48小时后上、下呼吸道及肺已被全面感染,96小时气囊已被感染,120小时输卵管已能分离到MG,卵巢始终分离不到MG。人工感染鸡自144小时便能在其所产蛋中分离出MG。药物治疗能在72小时内消除感染,油乳剂苗则需24天后逐渐降低蛋内MG分离率,药物卵内注射、种蛋药浴、高温处理均能杀死卵内MG,但以研制的种蛋浸泡剂药浴效果为最好。 相似文献
20.
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