犊牛腹泻的原因及防治措施

正犊牛腹泻是养牛业常见疾病,一年四季均可发病,在规模化养牛场中发病率很高,犊牛发病之后,会出现拉稀、呕吐、脱水消瘦等临床症状,影响犊牛的生长发育。由于初生犊牛抵抗力较差,一旦感染腹泻病,会给养殖户造成较大的经济损失。因此了解引发犊牛腹泻的因素,掌握有效诊治方法及防控措施,才能在养殖中获得预期的经济效益。1 发病病因依据腹泻的病因可分为感染性和非感染性两大类,但感染性腹泻是造成犊牛发病的主要原因,同时多种因素互相作用引发的腹泻,造     

犊牛病毒性腹泻及其综合防治

犊牛病毒性腹泻是一种养牛场常见的多发的传染病,也被称为黏膜病,我国将其列为二类传染病,常以犊牛发病多见~([1])。犊牛病毒性腹泻分布广泛,全世界范围内均有发生。该病以发热、腹泻、脱水、流产等为主要临床症状,常呈持续性感染状态。犊牛病毒性腹泻是严重危害养牛业的稳定生产,对世界各地的牛养殖业造成了巨大的经济损失。     

输血疗法在奶犊牛感染性出血性腹泻治疗中的应用技术

奶牛场犊牛养殖过程中,经常发生感染性腹泻,如伴发消化道出血则称之为出血性腹泻,常规的抗感染、止血、补液、止泻、退热和维持电解质平衡疗法效果欠佳,病死率极高,已成为困扰奶牛养殖主要难题之一.为此,河北省现代农业产业技术体系奶牛产业创新团队历经数年系统研究,形成了输血疗法在奶犊牛感染性出血性腹泻治疗中的应用技术模式,有效控制了出血性腹泻对犊牛健康的危害,现将该技术介绍如下: 1 感染性出血性腹泻的主要病原类别 河北省不同区域和不同养殖模式的奶牛养殖场中,多种致病菌、病毒和寄生虫的单一感染或两种病原乃至多种病原的混合感染,均可引起出血性犊牛腹泻.常见的致病菌有产肠毒素大肠杆菌、沙门氏菌、巴氏杆菌、弯曲杆菌、坏死杆菌和产气荚膜梭菌等;常见的病毒主要有病毒性腹泻病毒、轮状病毒、冠状病毒、传染性鼻气管炎病毒和细小病毒等;常见的寄生虫主要有球虫、微小隐孢子虫和贾第鞭毛虫.     

犊牛腹泻的原因及防治

<正>犊牛是牛群的基础,犊牛期生长发育的好坏对后天生产性能有很大影响。犊牛腹泻是犊牛常发疾病之一,临床常见急性腹泻,且危害相对严重,发病率和死亡率均很高,即使患病犊牛耐过康复,后天生产性能也会大大降低,饲养价值不高,致使牧场承受一定的经济损失,严重危害奶牛养殖业的健康发展。1发病原因犊牛出现腹泻症状的原因复杂,除了由一些常见的病原微生物引起的感染性因素,还与饲养水平、环境条件、日常管理等非感染性因素有关。犊牛腹泻病的病因复杂多样,这给     

犊牛腹泻病因及预防措施

<正>犊牛腹泻是犊牛培育过程中的常见疾病,甚至会直接导致犊牛夭折,从而。随着奶牛场犊牛饲养管理水平的提高,犊牛腹泻的流行和发生在一定程度上得到了控制,但由于引起该病发生的病原种类较多、感染情况较为复杂,使得奶牛场对该病的防控仍存在一定难度。给奶牛养殖业带来直接经济损失,本文分析了犊牛腹泻的发病原因及临床症状,并提出了防治犊牛腹泻的预防措施。1犊牛腹泻原因1.1非感染因素1.1.1饲养管理不当很多中小型养牛场的犊牛出现了     

犊牛病毒性腹泻及其综合防治

正犊牛病毒性腹泻是由牛病毒性腹泻病毒引起的一种养牛场常见而多发的传染病,也称黏膜病,我国将其列为二类传染病,以犊牛多发。犊牛病毒性腹泻分布广泛,全世界范围内均有发生。该病以发热、腹泻、脱水、流产等为主要临床症状,常呈持续性感染状态。犊牛病毒性腹泻严重危害养牛业的稳定生产,对世界各地的牛养殖业造成了巨大的经济损失。1流行特点牛病毒性腹泻在呈世界范围内分布,尤以养牛业发达的国家和地区最为严重。我国牛病毒性腹泻从上世纪80年代     

奶牛轮状病毒与纽布病毒混合感染诊断

正引起犊奶牛腹泻的病因大致可分为感染性因素和非感染性因素两大类。感染性因素包括细菌、病毒、寄生虫等,非感染性因素主要包括营养条件和环境因素等。常见的引起牛腹泻的病原微生物有牛轮状病毒(BRV)、牛冠状病毒(BCo V)、牛病毒性腹泻病毒(BVDV)、产肠毒素大肠杆菌(ETEC)、沙门氏菌(Salmonella)等。近期研究表明,牛诺如病毒(BNo V)和牛纽布病毒(BNe V)是新发腹泻病毒,已广泛流行。实验室检测对犊牛腹泻的准确诊断有重要作用。     

犊牛感染性腹泻的流行现状及综合防控

犊牛感染性腹泻是一类严重影响犊牛生长发育和畜牧养殖业经济效益的常见疾病。犊牛常因饲养条件不佳与环境卫生管理不当导致机体免疫功能下降而引起腹泻。近些年，犊牛感染性腹泻的比率有不断上升的趋势，致病因素主要是病毒、细菌和寄生虫等病原微生物。引起犊牛腹泻常见病原包括牛轮状病毒、牛冠状病毒、产肠毒素大肠埃希菌和隐孢子虫等，其中部分病原还会发生混合感染，导致犊牛继发呼吸道疾病、乳房炎、蹄病等，极大地增加治疗的难度。各个地区流行情况的监测有助于加强地区的治理，保护动物和人类健康，以免感染性腹泻的暴发。本文对犊牛感染性腹泻的流行现状、病原特征、检测和防治手段结合临床治疗经验进行综述，以期为犊牛感染性腹泻的防控提供参考依据。     

犊牛腹泻病的病因、症状与防治

犊牛发病的主要原因有饲养管理不当,环境因素,应激因素,细菌性腹泻,病毒性腹泻,寄生虫引起腹泻,微量元素缺乏等。犊牛腹泻分为营养腹泻和传染性腹泻两种,常见的多是细菌引起的。对已发病的犊牛提供相应的预防和治疗措施,如加强饲养管理,对奶牛舍及周围环境进行消毒,做好定期检查和免疫预防工作等。但无论是哪种病因引起的腹泻,只有在提高奶牛机体自身免疫力的情况下,才能有效地防制该病的发生。     

犊牛腹泻的发病原因及防治措施

犊牛腹泻是犊牛的常见病,严重时可导致犊牛死亡,是犊牛养殖中危害最为严重的疫病之一,给奶牛养殖业带来巨大的经济损失。笔者针对引起犊牛腹泻的几大原因,从犊牛的生理特性、母牛的营养状况、犊牛的饲养管理、病原体感染、外界环境及卫生状况等因素进行分析,再结合奶牛养殖场的实际情况,制订出一系列相应的综合防治措施。     

Dairy calf rearing unit and infectious diseases: diarrhea outbreak by bovine coronavirus as a model for the dispersion of pathogenic microorganisms

Dairy calf rearing unit is a management system that is only recently being implemented by some milk producer’s cooperatives in southern Brazil. However, aspects related to the health profile of the heifer calves that arrive in the rearing unit as well as about biosecurity practices and microbiological challenges have not yet been evaluated in this rearing system in a tropical country. Diarrhea is the main and most frequent consequence of enteric infections in newborn calves. This study, through some etiological and epidemiological characteristics of an outbreak of neonatal diarrhea, has the aim to alert to the possibility of pathogenic microorganism spread in a dairy heifer calf rearing unit. The diarrhea outbreak presented some non-regular characteristics observed in bovine coronavirus (BCoV) enteric infections in dairy calves. The spread of infection was extremely rapid (1 week); the attack rate (>?50%) was much higher than that observed in calves subjected to conventional rearing; and the age range (5 to 90 days) of the affected heifer calves was much broader than that often observed in the BCoV diarrhea worldwide. These unusual epidemiological characteristics observed in this BCoV diarrhea outbreak raise awareness of the health threat present in calf rearing units as well as of the easy and rapid viral spread in a population of young animals from different dairy herds and, therefore, with very distinct immunological status.

     

Biosecurity for neonatal gastrointestinal diseases.

Infectious diarrhea is an important cause of neonatal calf morbidity and mortality that results in significant economic losses in the beef and dairy industries. Although numerous risk factors related to the occurrence of neonatal diarrhea have been identified, they can all be categorized into those that are related to the calf, the pathogens involved, or the environment of the calf. The immune status of calves, specifically the level of passively acquired immunity through colostrum, is the major risk factor related to the calf and the occurrence of diarrhea. Although numerous pathogens have been implicated in the occurrence of neonatal diarrhea, only a relatively limited number are commonly involved. Most should be viewed as secondary opportunists rather than primary pathogens, because none are extraordinarily virulent, and with the exception of Salmonella spp., most are present within the gastrointestinal tract of many healthy, mature cattle. Important risk factors related to pathogens involved in neonatal calf diarrhea involve the size of the inoculum and the occurrence of multiple infections. Finally, when considering the environment and housing conditions in which beef and dairy calves may reside, it is clear that tremendous variations exist. Despite these variations, the risk factors associated with the environment of the calf are also those that are the most amenable to the implementation of general environmental control and monitoring strategies as well as specific biosecurity measures.     

Calf-level risk factors for neonatal diarrhea and shedding of Cryptosporidium parvum in Ontario dairy calves

This work was conducted to investigate calf-level factors that influence the risk of neonatal diarrhea and shedding of Cryptosporidium parvum oocysts in calves, on dairy farms in Ontario with histories of calf diarrhea or cryptosporidiosis. Fecal samples were collected weekly for 4 weeks from each of 1045 calves under 30 days of age on 11 dairy farms in south-western Ontario during the summer of 2003 and the winter of 2004. A questionnaire designed to gather information on calf-level management factors was administered on farm for each calf in the study. Samples were examined for C. parvum oocysts by microscopy, and a subset of specimens was also tested for enterotoxigenic Escherichia coli, Salmonella, bovine rotavirus and bovine coronavirus. The consistency of each sample was scored and recorded at the time of collection in order to assess the presence or absence of diarrhea. In addition, a blood sample was taken from each calf upon enrollment in the study, for assessment of maternal antibody transfer and for polymerase chain reaction testing for persistent bovine viral diarrhea virus infection. Using the GLLAMM function in Stata 9.0, multilevel regression techniques were employed to investigate associations between management practices and the risk of C. parvum shedding or diarrhea. C. parvum oocysts were detected in the feces of 78% of the 919 calves from which all four fecal samples had been collected. Furthermore, 73% of the 846 calves for which all four fecal consistency scores had been recorded were diarrheic at the time of collection of at least one sample. Significant predictors of the calf-level risk of C. parvum shedding included the use of calf diarrhea prophylaxis in pregnant cows, and the type of maternity facilities in which the calves were born. Factors associated with an increased risk of diarrhea were leaving the calf with the dam for more than an hour after birth, and the birth of a calf in the summer as opposed to winter. Calves shedding C. parvum oocysts had 5.3 (95% CI 4.4, 6.4) times the odds of diarrhea than non-shedding calves, controlling for other factors included in the final multivariable model. Furthermore, infected calves shedding more than 2.2 x 10(5) oocysts per gram of feces were more likely to scour than infected calves shedding lower numbers of oocysts (OR= 6.1, 95% CI 4.8, 7.8). The odds of diarrhea in calves shedding oocysts that had been allowed to remain with their dams for more than an hour were higher than the odds of diarrhea in shedding calves that had been separated from their dams within an hour after birth.     

Rotaviral and coronaviral diarrhea

A number of different viruses can be primary pathogens in the neonatal calf diarrhea complex. By far the most common viruses causing calfhood diarrhea found throughout the world are rotaviruses and coronaviruses. Primary infection of newborn calves with either one of these viruses can cause severe intestinal alterations and diarrhea. Rotaviruses can produce high-morbidity outbreaks of diarrhea in calves under 10 days of age. Morality is variable mainly owing to secondary bacterial infections and electrolyte imbalances. Rotavirus infection of the small intestinal mucosa leads to loss of enterocytes of the upper third of the intestinal villi with subsequent villous atrophy and malabsorption. There is growing evidence that different rotavirus serotypes of different pathogenicity exist. Coronavirus infections can produce high-morbidity outbreaks of diarrhea in calves under 20 days of age, with variable mortality due to secondary complications. Coronaviruses affect not only the small intestinal mucosa, producing significant villous atrophy, but also the colon, causing a very severe intestinal damage that can lead to death due to subsequent electrolyte disturbances. All coronaviruses associated with neonatal calf diarrhea appear to be of the same serotype. The etiologic diagnosis of viral diarrheas of calves requires the support of the laboratory. One of the most useful diagnostic methods is the examination of fecal extracts for the presence of virus particles by electron microscopy. Other antigen-detection procedures like enzyme immunoassays have been found to be useful in the diagnosis of rotaviral diarrheas. The sample of choice for these diagnostic tests is a fresh fecal sample collected directly from the calf as close as possible to the onset of diarrhea. Samples from more than one calf during the outbreak enhance the laboratory ability to establish a proper viral diagnosis.     

Attaching and effacing Escherichia coli infection as a cause of diarrhea in young calves

A form of enteric Escherichia coli infection was identified in 60 calves from 59 farming operations. The E coli responsible for these infections principally colonized the colon, inducing a distinctive lesion described as attaching and effacing. Hemorrhagic enterocolitis or blood in the feces was observed on 40% of the farms. Of affected calves, 86.6% were dairy calves (average age, 11.8 days). Forty-four calves were infected concurrently with other enteropathogens (cryptosporidia, rotavirus, coronavirus, enterotoxigenic E coli, bovine viral diarrhea virus, coccidia). Verotoxin-producing E coli was recovered from 31 calves; 8 were serotype O111:NM isolates, 3 were serotype O5:NM, and 1 was serotype O26:NM.     

Virus-like particles, 45 to 65 nm, in intestinal contents of neonatal calves.

Enveloped virus particles 45 to 65 nm in diameter, tentatively called minicorona virus, were detected by electron microscopy in the intestinal contents of one normal and seven diarrheic calves in Quebec dairy herds. The agent was shown to be antigenically unrelated to the Nebraska calf diarrhea coronavirus and to the bovine viral diarrhea virus by counterimmunoelectrophoresis and fluorescent-antibody techniques. Antibodies against these particles were demonstrated in the serum of affected calves using immunoelectron microscopy. The agent could not be isolated in cell cultures and its possible role as etiological agent in calf diarrhea is still to be determined.     

哺乳期犊牛健康管理

哺乳期犊牛是奶牛生命周期的开始,也是奶牛整个生命周期中最为脆弱的阶段,其健康状况可直接影响牧场的可持续发展和经营效率。在哺乳期,犊牛可面临多种疾病的挑战,但消化道疾病和呼吸道疾病是全球奶牛养殖业面临的共性问题。本文对哺乳期犊牛健康状况、初乳管理、犊牛腹泻和呼吸道疾病的管理进行了梳理,并对其防控提出了建议。初乳管理方面分析了影响初乳质量的因素、初乳储存与处理和饲喂管理;犊牛健康管理部分叙述了产圈管理、饲养环境和饲喂方式、营养及饲喂管理、疫苗免疫、通风、疾病早期诊断、应激管理和患犊管理。     

Prevalence of Cryptosporidium parvum infection in southwestern Ontario and its association with diarrhea in neonatal dairy calves

Cryptosporidium parvum infection was detected in 203 (40.6%) of 500 Ontario dairy calves aged 7 to 21 d, on a convenience sample of 51 farms with a history of calf diarrhea. Within-farm prevalence ranged from 0% to 70%, and both shedding and intensity of shedding were significantly associated with diarrhea. This parasite appears to be common in Ontario dairy calves and important as a cause of dairy calf scours in the province.     

Losses over a 2-year period associated with fetal infection with the bovine viral diarrhea virus in a beef cow-calf herd in Saskatchewan.

In 1992, significant calf losses occurred between birth and weaning in a 650-cow Saskatchewan beef herd. These losses occurred subsequent to ill-thrift and disease, and every calf necropsied was found to be persistently infected with bovine viral diarrhea virus (BVDV). The objectives of this study were to describe the losses associated with fetal infection with BVDV in this herd and to determine why they occurred. For investigative purposes, blood samples were collected from the entire cow herd and the surviving calves at pregnancy testing in 1992, and tested by virus isolation for BVDV. Between 51 and 71 persistently infected calves were born in 1992. Bovine viral diarrhea virus was only isolated from calves. The only confirmed fetal infections with BVDV were recorded as the birth of persistently infected calves. However, abortions, reduced pregnancy rates, and delayed calvings were also recorded in the cow herd and may have been the result of fetal infections. The herd was monitored again in 1993. Fetal infections with BVDV were recorded as the birth of stunted, deformed, and persistently infected calves. The greatest losses due to fetal infection with BVDV in the 2 years of this study occurred in cows that were 3-years-old at calving (second calves). Bovine viral diarrhea virus appears to have remained endemic in this herd by transmission from persistently infected calves on young 3- and 4-year-old cows to naive calved 2-year-old cows that were mingled with them annually for rebreeding. Significant numbers of the 2-year-old cows remained naive to BVDV, because they were segregated from persistently infected calves at weaning, preventing cross-infection with BVDV.