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1.
１疾病因素１．１非典型性新城疫（ND）已接种新城疫疫苗的鸡群发病后呈非典型性经过，无明显的临床症状和病理变化，其发病率和死亡率都很低。但病鸡产蛋量急剧下降，产蛋高峰上不去，软壳蛋、薄壳蛋、小蛋明显增多，拉稀症状明显。引发这种现象的原因有以下几点：１．１．１疫苗的质量存在问题或疫苗在生产运输、保存等环节管理不善。１．１．２鸡群免疫时，疾病的隐性感染影响了鸡对疫苗的正常免疫应答，如法氏囊病、鸡球虫病、黄曲霉素中毒等直接或间接地影响了免疫球蛋白的产生，导致免疫机能不全和免疫抑制。１．１．３饲养管理不善… 相似文献
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正常情况下，蛋鸡开产后５～７周即达到产蛋高峰并维持８个月左右，以后的产蛋率逐渐下降。但有的鸡场和专业户所饲养的蛋鸡开产、高峰和维持时间等延迟或缩短；产蛋率不稳定，达不到高峰；高峰期或产蛋上升期产蛋突然下降等，严重影响了经济效益的提高。由于近几年流行产蛋下降综合征，有些鸡场和专业户发现鸡产蛋下降就怀疑得了产蛋下降综合征。其实，引起产蛋下降的原因很多，如某些传染病、饲养管理不善、用药不当、各种应激因素存在等都会引起产蛋下降，现将引起产蛋下降的原因及防治措施分述如下。１ 饲料方面１１ 饲料配制不合理… 相似文献
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在当前的养鸡生产中，多种疾病直接影响着蛋鸡的产蛋率，有的疾病可使产蛋率下降到３０％，有的几乎可使蛋鸡全部停产。经过治疗，病愈后的产蛋率也只能维持在６０％左右，达不到产蛋高峰或恢复不到病前的产蛋水平。其主要原因是养殖户在鸡发病期间和病愈后的饲养管理措施不当，致使鸡的生产性能得不到正常的发挥。根据上述原因，建议采取如下措施：１ 根据病情及时调整饲养管理方案 蛋鸡进入产蛋期后，许多疾病都可以引起产蛋率的严重下降，如新城疫、禽流感、慢性呼吸道病。大肠杆菌病等，危害都比较大。但是，只要管理得当，产蛋率仍可以… 相似文献
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范宝柱 《养殖与饲料．饲料世界》2006,(3):45-47
产蛋性能低下，主要表现为到高峰期的鸡没有出现产蛋高峰，饲养至200日龄左右时日产蛋率还在60％～80％徘徊，或者虽上了高峰期，但维持的时间太短；产蛋异常下降主要表现为蛋鸡在产蛋期间产蛋率的急剧下降和缓慢下降。 相似文献
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产蛋性能低下，主要表现为到高峰期的鸡没有出现产蛋高峰，饲养至200日龄左右的日产蛋率还在60％～80％徘徊，或者虽上了高峰期，但维持的时间太短；产蛋异常下降主要表现为蛋鸡在产蛋期间产蛋率的突然下降。 相似文献
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正常情况下，蛋鸡开产后5～7周即达到产蛋高峰并维持8个月左右，以后的产蛋率逐渐下降。但有的鸡场和专业户所饲养的蛋鸡开产、高峰和维持时间等延迟或缩短；产蛋率不稳定，达不到高峰；高峰期或产蛋上升期产蛋突然下降等，严重影响了经济效益的提高。有些鸡场和专业户发现鸡产蛋下降就怀疑得了产蛋下降综合征等传染病。其实，引起产蛋下降的原因很多，除某些传染病外，饲养管理不善、用药不当、各种应激因素等都会引起产蛋下降，现分述如下。 相似文献
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正常情况下，蛋鸡开产后５～７周即达到产蛋高峰并维持８个月左右，以后的产蛋率逐渐下降。但有的鸡场和专业户所饲养的蛋鸡开产、高峰和维持时间等延迟或缩短；产蛋率不稳定，达不到高峰；高峰期或产蛋上升期产蛋突然下降等，严重影响了经济效益的提高。由于近几年流行产... 相似文献
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《北方牧业》2006,(24)
<正> 最近在养鸡户中间流传一种“怪”病:鸡群精神很好,吃料不少,也没有任何异常表现,但就是产蛋率上不去,或者刚上产蛋高峰就开始降蛋;有的产蛋高峰期间产蛋率忽升忽降;有的还出现不明原因的瘫鸡,饲喂微量元素和维生素也没有明显改善;有的以为是变异的流感,使用大剂量流感疫苗免疫也无法控制病情。其实,他们所认为的这种怪病就是非典型新城疫。其症状主要表现为产蛋率下降,产蛋异常,轻微的呼吸道症状。由于目前养鸡户对于新城疫的普遍重视,以及新城疫疫苗的广泛使用,该病的典型病例已经不多见了,取而代之的是非典型的病例。1 病例河北省行唐县某户饲养了2000只180日龄的鸡,自开产起,便开始出现零星死鸡,少时每天死一两只,多时每天死四五只。晚上在鸡舍外可听到有呼 相似文献
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产蛋鸡无产蛋高峰是指鸡产蛋性能低下,主要表现为到达产蛋高峰期的鸡没有出现产蛋高峰,或者说虽然达到了产蛋高峰,但维持的时间太短。产蛋率异常下降的主要表现为蛋鸡在产蛋期间产蛋率的急剧下降和缓慢下降。 相似文献
10.
彭善智 《畜牧兽医科技信息》2008,(1):72-73
正常情况下,蛋鸡开产后5～7周即达到产蛋高峰并维持8个月左右,以后的产蛋率逐渐下降.但有的鸡场和专业户所饲养的蛋鸡开产、高峰和维持时间等延迟或缩短;产蛋率不稳定,达不到高峰;高峰期或产蛋上升期产蛋突然下降等,严重影响了经济效益的提高.有些鸡场和专业户发现鸡产蛋下降就怀疑得了产蛋下降综合征等传染病. 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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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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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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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
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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