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1.
Three similar flocks of broiler breeder parent chickens that had been given live infections bronchitis (IB) vaccines during rearing were injected at 20 weeks of age with three different oil emulsion vaccines: a commercial monovalent Newcastle disease (ND) vaccine (flock A); an experimental bivalent vaccine containing ND and infectious bursal disease (IBD) components (flock B); and an experimental trivalent vaccine containing ND, IBD and IB components (flock C). One week after vaccination 40 hens from flock A and 40 from flock C were taken to the laboratory and their egg yields individually recorded. At 37 weeks of age they were challenged by aerosol exposure to virulent IB virus. The egg production dropped significantly in the hens from flock A but not in the hens from flock C. On the farm, flock C showed a higher mean IB virus antibody titre four weeks after vaccination but titres rose in all three flocks indicating the presence of active IB virus infection. No differences in egg yields were found between the three farm flocks.  相似文献   

2.
Managing avian flock emergencies requires a thorough history, physical examination, and record review before instituting appropriate therapy. Although the general thought processes are similar between approaching a sick individual bird and a "diseased" aviary, the actual steps are different. Infectious diseases are often a component of aviary emergencies but are rarely the primary cause of flock "disease." Managing flock emergencies typically goes beyond addressing individual pathogens. Recognizing, evaluating, and treating flock emergencies are discussed with the intent to provide a better understanding of flock health medicine principles.  相似文献   

3.
Laboratory examination of all birds that were culled or died during an eight-month period in two commerical laying flocks was performed to reveal the causes of disease and their prevalence. The average weekly total of diseased birds was greater in one flock (60-69) than the other (27-37). This resulted mainly from a high incidence in the former flock of leucoses and sarcomas, although losses due to fatty liver syndrome, prolapse and cannibalism and cage layer fatigue were also marginally greater in this flock than the second. Haemangiomas occurred more frequently in the flock with the higher disease level. A total of 273 hens of the 2,000 examined from this flock had single or multiple haemangiomas. Special features of the major causes of disease were outlined and discussed. A conclusion made from this study was that histopathological examination is necessary for accurate diagnosis of avian tumours.  相似文献   

4.
山东兖州某商品代肉鸡场的 2 0日龄肉鸡开始出现大批死亡 ,剖检发现肝脏、脾脏、肾脏和心脏等主要脏器均出现大小不等的肿瘤结节 ,采用细胞培养和间接荧光抗体试验的方法从这些病料中同时分离到了禽网状内皮组织增生病病毒 (REV)和马立克氏病病毒 (MDV) ,通过组织病理学检查和斑点杂交的方法表明该鸡场的疫病为REV和MDV共感染引起的肿瘤病。这是国内从商品代肉鸡中同时分离到REV和MDV的首次报道  相似文献   

5.
Caseous lymphadenitis (CLA), a chronic bacterial disease of sheep and goats caused by Corynebacterium pseudotuberculosis, could be controlled by eradication of infected carriers. This study aimed at validation of a whole blood interferon-gamma (IFN-gamma) enzyme immunoassay (EIA) (Bovigam, Pfizer) in naturally infected sheep for use in eradication of infection from a flock. This assay used formalin-inactivated whole bacterial cells as antigen. The sensitivity of the whole cell assay was improved by increasing both the volume of blood and the number of bacterial cells. The assay was validated in experimentally infected sheep and in a flock of known-negative sheep, as well as in a naturally infected flock, a proportion of which was vaccinated with a commercial CLA vaccine. An optical density (540nm) (OD) cut-off of 0.09 was effective in classifying animals as test positive or negative in the naturally infected flock, although there was variation in OD between visits, notably with weakly reacting animals. The test had a sensitivity of 91% and a specificity of 98%. Postmortem data supported the results in test-negative animals. Visit-to-visit variation in IFN-gamma EIA OD in the naturally infected flock as well as CLA disease status was used to develop an algorithm for the eradication of CLA from a known infected flock. The whole blood IFN-gamma assay shows promise for eradication of caseous lymphadenitis from sheep flocks.  相似文献   

6.
Outbreaks of clinical chicken anaemia in four broiler chicken flocks affected chicks which were all the progeny of the same parent flock. Three of the flocks were reared on farms in the south-east of England and in these flocks clinical disease did not occur in other chicks of the same age. The fourth flock was reared in a positive-pressure isolator and clinical disease appeared at 10 days of age. Chicken anaemia agent was isolated from three of the flocks. The clinical signs, post mortem lesions and histopathological changes were similar to those reported in outbreaks of the disease in other countries. The parent flock seroconverted to chicken anaemia agent, as determined by fluorescent antibody tests, during the course of the outbreaks.  相似文献   

7.
A virus indistinguishable from that causing maedi/visna has been isolated from a sheep flock in Great Britain. The virus was identified in cell cultures using immunofluorescent and electron microscopical techniques. The complement fixation test and the agar gel immunodiffusion test were used to assess the proportion of serological reactors within the flock. There has been no evidence of clinical disease in the flock into which foreign imports were introduced in the years prior to 1976.  相似文献   

8.
As avian health professionals, when there is an increased morbidity or mortality in a waterfowl flock, we are often concerned with disease diagnostic and treatment regimens. However, one area that should not be overlooked is waterfowl husbandry, especially if we want to develop preventive medicine strategies for the flock. Husbandry aspects need to be considered because certain management factors may predispose the waterfowl flock to certain diseases. Avian health professionals should also be aware of the common duck and geese breeds that are commonly kept in backyard flock. This type of information can provide information on flock personality and unique anatomical characteristics. In addition, understanding the different breeds will allow avian health professionals to assist in recommending the appropriate waterfowl to our clients. Waterfowl have unique husbandry requirements when compared to other poultry species, and having a better understanding of husbandry aspects like housing and feeding can help to prevent diseases from reoccurring in the flock. By having a better understanding of waterfowl husbandry, we can ensure that our waterfowl patients receive the best medical care and continue to remain healthy.  相似文献   

9.
Oral Newcastle disease vaccine, strain V4, was administered to an open-range multi-age chicken flock. Adult birds in this flock had low levels of haemagglutination inhibition antibody as a result of vaccination of the flock with strain V4 more than 3 years previously and apparent persistence of the vaccine virus. Eight clutches of chicks were hatched over a period of 3 months. Vaccine, given at fortnightly intervals, was restricted to young chicks by creep feeding. Chicks in all the clutches produced antibody in response to vaccination, and levels of antibody in the adult flock increased as the first clutches were responding to vaccination. When oral vaccine is used in the field, restriction of vaccination to chicks could conserve without reducing the efficacy of vaccination.  相似文献   

10.
The Cheviot flock at the Institute for Animal Health's Neuropathogenesis Unit (npu) has endemic scrapie, which affects primarily vrq/vrq sheep and at high frequency. A new flock with a full range of PrP genotypes, including the highly susceptible vrq/vrq, has been produced on a separate site, from animals in the npu breeding flock, and it remains scrapie-free after eight years. In contrast, in a parallel flock at the npu farm, scrapie has reappeared after five years, although the animals were kept in separate accommodation from the scrapie-affected sheep. During this time the npu breeding flock continued to have scrapie cases. Although it is known that highly susceptible sheep can remain free of infection in a clean environment, this is the first report of the infection being removed successfully from the bloodlines of scrapie-affected sheep. The results confirm that scrapie is not a genetic disease dependent only on the PrP gene sequence, but requires both genetic susceptibility and an infectious agent.  相似文献   

11.
某种鸡场一群艾维茵父母代种鸡中出现“假性母鸡”,剖检发现输卵管畸形。这批种鸡在17日龄时发生过某传染病。进行发病情况调查、对病死雏鸡的剖检和开产期病死母鸡的剖检、病料鸡胚感染和传代试验及新城疫病毒干扰试验。结果,鸡胚感染中第3代出现侏儒胚,干扰组的新城疫血凝价均低于20,对照组新城疫血凝价高于40。综合分析,可以判定该雏鸡在3周龄发生的疾病是鸡传染性支气管炎,以及可以确定该鸡群中不少鸡只出现输卵管畸形是由鸡传染性支气管炎病毒早期感染而引起的。  相似文献   

12.
The first outbreak of tenosynovitis caused by infection with REO virus in the Netherlands, involving 15 broiler flocks, is described. The disease could be reproduced easily by subcutaneous, oral and contact infection of susceptible broilers with the isolated virus. The 15 affected flocks all came from one broiler parent flock and were fed with feed from one mill (A). Twenty other flocks, also coming from this parent flock and reared in the same period on feed from another feed mill (B) did not suffer from tenosynovitis. The parent flock showed no disease symptoms but seroconversion to REO virus occurred after the onset of the problems in the offspring. The influences of the different feeds on the course of the synovitis could be reproduced experimentally, but with less extreme differences than observed in the field. The possible ways in which feeds may influence tenosynovitis causing REO virus infection are discussed.  相似文献   

13.
This study reports a prevalence and risk factor survey of brucellosis in small ruminants in Southern Zone of Tigray Region, Northern Ethiopia between October 2011 and April 2012 to determine the sero-prevalence of small-ruminant brucellosis and to identify associated risk factors for the occurrence of disease in small ruminants under extensive production system. Multistage random sampling was followed to select locations, flocks, and individual animals. Laboratory analysis of serum samples provided sero-prevalence estimates for flocks and geographic location. Information on risk factors at the individual and flock level was obtained by examination of individual animal and a questionnaire interview to flock owners. The overall individual animal-level sero-prevalence of brucellosis in small ruminants was 3.5 % and flock level sero-prevalence was 28.3 %, and the within-flock sero-prevalence was ranged from 0 % to 22.2 % based on the Complement Fixation Test. Multivariable logistic regression showed that the major risk factors for flock level sero-positivity were flock size and abortion history. This study showed that small-ruminant brucellosis is prevalent in the study area. Larger flock size and history of previous abortion in the flock were major risk factors identified for sero-positivity of small-ruminant brucellosis.  相似文献   

14.
OBJECTIVE: The aim of this study was to apply whole flock testing over time to determine the prevalence, distribution and spread of infection in a recently infected flock, with a view to planning intervention strategies for disease control. PROCEDURE: Serology, pooled faecal culture (PFC) and histology were used to determine the distribution and persistence of infection in a sheep flock in south east New South Wales between 1997 and 2002. Partial flock testing was done up to June 2000, after which annual whole flock testing, using PFC was performed. RESULTS: Faecal shedding of M a paratuberculosis was not detected in home-bred sheep until 7 years after the introduction of infected sheep in 1993. For at least 7 years there was clustering of infection and shedding within two age groups only. The infected groups appeared to have been exposed to infection (mycobacterial contamination) at an early age (<12 months) and commenced shedding at 5 years of age or older. Groups that were exposed to contamination as adults did not shed detectable amounts of M a paratuberculosis during the study period. CONCLUSION: Clustering of detectable infection in age groups of sheep that were exposed as lambs was a feature on this farm, providing indirect evidence of finite duration of survival of M a paratuberculosis on pasture and the influence of age on the susceptibility of sheep to develop detectable M a paratuberculosis infection. Spread of infection occurred very slowly and was probably related to the long incubation period (exposure to shedding interval) of 5 years observed on this farm. The findings suggest that partial flock culling, selective grazing management and vaccination could lead to a reduction in mycobacterial contamination on farm to a level at which patent infection no longer occurs. Better understanding of disease spread within flocks over time through flock profiling using PFC will help in devising surveillance strategies (including testing protocols for market assurance testing) to detect infected flocks where there has been clustering and slow spread of infection.  相似文献   

15.
Objective To compare haematological values and lymphocyte phenotypes in the peripheral blood of fleece rot-resistant and -susceptible sheep.
Procedure Experiments were conducted on 2- and 3-year-old Merino rams, flock 1 (17 rams) and flock 2 (32 rams), respectively. Within each flock, individual rams were classified as fleece rot-resistant or -susceptible, based on established criteria. Total and differential white cell counts, and indirect fluorescent antibody tests specific for B cells and T cells were performed on all sheep. The concentration of various subsets of circulating lymphocytes was then determined in each sheep.
Results There were no significant differences between fleece rot-resistant and -susceptible sheep from either flock in the mean total or differential white cell counts. However, fleece rot-resistant rams in flock 1 did have a significantly higher concentration of circulating SBU-T1+ cells than fleece rot-susceptible rams from the same flock. No such difference was noted in the rams from flock 2. While all rams in flock 1 were free of clinical fleece rot, 24 rams in flock 2 (comprising all 17 fleece rot-susceptible and 7 of 15 fleece rot-resistant animals) had clinical signs of the disease. Fleece rot-free rams in this flock (irrespective of their classification as fleece rot-resistant or -susceptible) had significantly higher concentrations of circulating SBU-T1+ cells compared with fleece rot-affected animals. They also had significantly higher concentrations of circulating B cells, and total lymphocytes.
Conclusions An examination of peripheral blood lymphocyte subsets in fleece rot-resistant and -susceptible sheep revealed a possible association between resistance to fleece rot and the concentration of circulating SBU-T1+ cells.  相似文献   

16.
SUMMARY The occurrence of intoxication due to type C botulinum toxin in broiler fowl is described. The disease occurred during warm weather and appeared to be due to ingestion of carcases which had been stored for only 2 to 3 days within the poultry shed. Botulism resulted in a mortality of less than 1% of the flock but caused concern in deciding whether to submit the flock for slaughter for human consumption. The diagnosis and public health aspects of the disease are discussed.  相似文献   

17.
An enteric disease characterised by diarrhoea and ill thrift affected 12 of a flock of 700 six- to 12-month-old ewe lambs in Cornwall between December 1996 and September 1997. The affected lambs were undersized, became thin and suffered an unremitting diarrhoea until they died. The illness lasted for three to 14 days, although, with hindsight, the owner considered that the lambs had been below average size before the enteric signs developed. The outbreak ceased only as a result of the dispersal sale of the flock as breeding ewes. The flock had been purchased from different sources, but 11 of the cases occurred in a group of 40 purchased from one source. Postmortem, the alimentary changes resembled mucosal disease in cattle, and immunostaining of histological sections of the affected tissues revealed pestiviral antigen. Non-cytopathic pestiviruses were isolated from the lesions of two of the affected lambs and from the blood of several clinically normal ewe lambs from the same group. All the pestivirus isolates were typed as Border disease virus.  相似文献   

18.
Forty-six percent of 3,585 serum samples from 174 broiler-breeder chicken flocks in 9 states were positive for the precipitating antibody of hemorrhagic enteritis (HE) of turkeys/marble spleen disease (MSD) of pheasants. Seroconversion was detected only in flocks 19 weeks of age and older. The percent of individual serum samples positive within a flock increased with the age of the flock.  相似文献   

19.
Scrapie free adult sheep were introduced to a sheep flock specifically maintained to maximise scrapie infection. Native born sheep of the highly susceptible VRQ/VRQ genotype in this flock show highly efficient transmission, evidenced by 100% infection, with an age at death of less than 2 years. Infection in introduced sheep was identified by biopsy of tonsilar and nictitating membrane lymphoid tissue. Progeny of these sheep were monitored and clinical disease confirmed by examination of the brain using routine diagnostic methods. Na?ve sheep of New Zealand origin introduced to the flock in adulthood became infected, demonstrating that lateral transmission had occurred. Lambs born to introduced ewes became infected and died at the same age as lambs born to native ewes, consistent with lateral transmission of scrapie to lambs. Although maternal transmission cannot be totally excluded for the lambs in this study, the data are consistent with lateral transmission being the most important means of spread leading to the high incidence of scrapie observed in this flock.  相似文献   

20.
In an imported flock of sheep from South Africa, an ewe became partially anorexic and gradually losing weight and conditions. The paratuberculosis (Johne's disease) was confirmed on clinical, faecal and histopathological examination. Cultural examination remained doubtful. Serological investigation of other sheep in the flock and at other farm reacted to antibodies of Mycobacterium paratuberculosis on complement fixation test. The study suggests that the disease is actively spreading. This is the first report of ovine paratuberculosis in the Republic of Zambia.  相似文献   

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