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1.
Extract

Bovine respiratory disease (BRD) is a major health problem of cattle all over the world. Financial losses arise from the loss in production, cost of treatment and mortality. Incidence varies with seasons, the highest occurring in autumn and winter. Virus infections such as infectious bovine rhinotracheitis (IBR), parainfluenza 3 (P13) and bovine respiratory syncytial (BRS) viruses have all been incriminated as causes for BRD. It has been suggested that bovine viral diarrhoea (BVD) virus may also contribute to BRD because of its immunosuppressive effects, thus increasing the susceptibility of the host to other respiratory pathogens.  相似文献   

2.
A total of 1745 healthy cattle from 295 farms in Saskatchewan and Alberta was tested by ELISA for antibodies to four viruses. Antibodies to infectious bovine rhinotracheitis (IBR) virus were found in 37.8% of sera (59.5% of properties), to parainfluenza 3 (PI3) virus in 93.9% of sera (99.7% of properties), to bovine respiratory syncytial (BRS) virus in 78.5% of sera (86.6% of properties), and to bovine viral diarrhea (BVD) virus in 40.6% of sera (66.7% of properties)

The prevalence of PI3 viral antibodies among Saskatchewan cattle was not affected by district of origin, breed, sex, age, or vaccination practices, though BRS viral antibodies appeared less frequent in young, male, and unvaccinated animals. Antibodies to IBR and BVD viruses were less prevalent in the Prince Albert/Tisdale districts and in young, male, and unvaccinated animals, but were more common in Holstein cattle. Antibodies to IBR virus appeared less frequent in Herefords. Antibodies were more prevalent in cattle which had been vaccinated against IBR, BRS, and BVD virus infections.

The relatively small number of cattle sampled from Alberta had a similar prevalence of antibodies to PI3 and BRS viruses to that seen in cattle in Saskatchewan, though IBR and BVD prevalence rates were lower.

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3.
Serum samples were collected from early weaned fall calves shortly after the onset of respiratory tract disease. Antibody titers to infectious bovine rhinotracheitis (IBR) virus, parainfluenza type 3 (PI-3) virus, bovine viral diarrhea (BVD) virus, bovine adenovirus type 3 (BAV-3), and bovine respiratory syncytial virus (BRSV) were determined on paired (acute and convalescent) serums. Seroconversion rate (a fourfold or greater rise in antibody titer) for IBR virus was 4.3%, PI-3 virus--16.3%, BVD virus--9.6%, and BAV-3--2.2%. Seroconversion for BRSV was 45.4%. An increased rate of seroconversion for IBR, PI-3, and BVD viruses and BAV-3 was observed in the presence of BRSV seroconversion. These results suggest that BRSV may facilitate infection by other viruses. Results of virus isolation procedures from these calves were negative.  相似文献   

4.
Thirty-five vaccinates and 29 control beef calves from five farms were studied. Vaccinates in group 1 received a modified live virus vaccine against infectious bovine rhinotracheitis (IBR) and bovine virus diarrhea (BVD) 30 days after shipment; vaccinates in groups 2, 3 and 4 received live virus vaccines agains IBR and bovine parainfluenza 3 (PI3) seven to 17 days before shipment. Half of group 5 were given bovine origin antiserum containing antibodies against IBR, BVD and PI3. Three weeks later, the animals that had received serum were given a live modified vaccine containing IBR, BVD and PI3. In group 1, WBC counts were lower in the vaccinates than in the controls for two weeks after vaccination. WBC counts in groups 3 and 4 were higher in vaccinates than in controls after addition to the feedlot. Seroconversions to BVD virus occured in all groups. Clinical disease apparently due to BVD affected one vaccinated calf in group 2 and eight calves in group 5. Combined weight gains were significantly higher in three groups of calves vaccinated before shipment compared to unvaccinated control animals after addition to the feedlot. Vaccination with IBR and PI3 live virus vaccines should be given at least 17 days before shipment to feedlots containing infected cattle. Antiserum containing antibodies against the three viruses showed no apparent advantage in preventing clinical respiratory disease over control calves not receiving the serum.  相似文献   

5.
More than 400 small ruminant sera from Za?re were screened for antibodies to IBR, CHV2, BVD, bovine and ovine PI3, BRS and rinderpest viruses. Sera from local animals were negative for BVD, PI3 and rinderpest viruses: 8% of sera were positive for IBR virus, all with higher titers to CHV2; 31% of sera were positive to BRS virus.  相似文献   

6.
Blood samples from 32 groups of calves (n = 700) were taken on arrival and after 28-35 days at the feedlot. Eleven groups were housed in feedlots in Ontario, and 21 groups in feedlots in Alberta. Serum antibody titers to bovine viral diarrhea virus (BVDV), bovine respiratory syncytial virus (BRSV), parainfluenza virus type 3 (PIV-3), infectious bovine rhinotracheitis virus (IBRV), Mycoplasma dispar and M. bovis, plus data on bovine corona virus (BCV) from a previous study were investigated for their association with the risk of bovine respiratory disease (BRD), and with 28-day weight change, both before and after controlling for titers to Pasteurella haemolytica and Haemophilus somnus. Exposure to IBRV and M. bovis was infrequent, and although exposure to PIV-3 was more common, none of these agents had important associations with BRD. Higher titers to BVDV, BRSV, and BCV on arrival were associated with reduced risks of BRD and increased weight gains. However, there was some variation in these relationships and higher arrival titers to BVDV and BRSV in a subset of the calves were associated with increased risks of BRD. Titer increases to BVDV were associated with a higher risk of BRD and lower weight gains. Titer increases to BRSV were not usually associated with the occurrence of BRD, but titer increases to BRSV in a subset of calves that were vaccinated against BRSV, on arrival, were associated with an elevated risk of BRD. Of all the agents studied, BVDV had the most consistent associations with elevated risk of BRD and lower weight gains. Higher BRSV arrival titers were related to lower risk of BRD and higher weight gains; in some instances titer increases to BRSV were associated with higher BRD risk. Higher titers to BCV on arrival were related to reduced risks of BRD. Practical ways of adequately preventing the negative effects of these agents are still needed.  相似文献   

7.
Acute and convalescent serum samples were taken from 59 calves with signs of respiratory disease (cases) and 60 clinically normal animals (controls) during their first month in the feedlot. Sera were analyzed for antibodies to bovine parainfluenza 3 (PI3) virus by hemagglutination inhibition, to bovine viral diarrhea (BVD) virus, bovine respiratory syncytial (BRS) virus and bovine herpesvirus 1 (BHV1) by virus neutralization, and to Pasteurella haemolytica by indirect agglutination (PhIA) and cytotoxin neutralization (PhCN) tests. There was minimal evidence of serological activity to BHV1. Serological activity to the other agents occurred commonly and the prevalence of acute titers and their mean values was similar in case and control groups. Mean convalescent PI3 and P. haemolytica (PhIA) titers were higher in controls than cases (p < 0.01) but, otherwise, convalescent titers did not differ between groups. The incidence of seroconversion was similar in both groups for all agents except for PI3 virus which was more frequent in controls than cases (p < 0.0001). There was a positive association between PhIA and CN seroconversion and isolation of P. haemolytica from bronchoalveolar lavage (BAL) fluid (p < 0.1). The measure of agreement (kappa) between seroconversion with the P. haemolytica PhIA and PhCN tests was 0.51. Bacteriological and cytological evaluations of the respiratory tract were made using BAL. No associations were evident between serological titers and pulmonary cytology. A multivariate logistic analysis was used to evaluate associations between disease status and serological, bacteriological and cytological data. Cases were positively associated with the presence of neutrophils and Pasteurella multocida in BAL fluid and negatively associated with PI3 virus and PhIA seroconversion.  相似文献   

8.
The associations, at the group level, between serological titer to Pasteurella haemolytica surface antigens (Ph), Pasteurella haemolytica cytotoxin (Ph-cytox), infectious bovine rhinotracheitis virus (IBRV), bovine virus diarrhea virus (BVDV), parainfluenza-3 virus (PIV3), respiratory syncytial virus (RSV), Mycoplasma dispar (Md), M. bovis (Mb), and respiratory disease treatment rates, relapse rates, and 28 day weight gains were investigated in 14 groups of calves entering two feedlots during years 1983-1985, in Ontario. Based on least squares regression analyses, seroconversion rates to Mb and BVDV were predictive of increased respiratory disease rates, and seroconversion rates to Ph, Ph-cytox, Md and PIV3 were predictive of decreased weight gains. The R2 for predicting weight gains was much higher than for morbidity rates (0.75 vs 0.47 respectively). Titer data were not predictive of relapse rates. Group level analyses were performed because calves are managed as groups (e.g. pens) in commercial feedlots. Only BVDV seroconversion rates were related to increased risk of respiratory disease at both the individual and group levels of organization. Mycoplasma may be important factors in causing respiratory disease, and their relationship to potentiating the effects of other respiratory pathogens needs further investigation.  相似文献   

9.
The prevalence of respiratory pathogens in diseased veal calves was determined in 24 respiratory disease outbreaks in 15 herds in Belgium. Bacteria were cultured from nasopharyngeal swabs and seroconversion against viruses and Mycoplasma bovis was determined on paired sera. At the individual calf level, Mycoplasma species, Mannheimia haemolytica and Pasteurella multocida, were isolated from 70.5 per cent, 21.5 per cent and 26.0 per cent of swabs, respectively. At the herd level, the presence of M bovis could be confirmed in 84.6 per cent of the herds examined. Seroconversion against bovine viral diarrhoea virus (BVDV) was present in 71.4 per cent of herds, parainfluenzavirus type 3 in 53.3 per cent, bovine respiratory syncytial virus in 40.0 per cent, bovine adenovirus type 3 in 46.7 per cent, bovine coronavirus in 30.0 per cent, and bovine herpesvirus type 1 in 26.7 per cent. At postmortem examination, Mycoplasma species could be cultured from 61.9 per cent of pneumonic lungs (n=21). Sixty per cent of calves tested were positive for BVDV (n=20), and 20.0 per cent were positive for bovine respiratory syncytial virus (n=16).  相似文献   

10.
The pneumonic lungs of 42 cattle from 26 feedlots were examined for the presence of mycoplasma, pathogenic bacteria and viruses. Four animals representative of two lots failed to yield mycoplasma. One of these yielded the virus of infectious bovine rhinotracheitis and Pasteurella hemolytica, the other yielded only P. P. multocida. Nine animals in eight lots yielded Mycoplasma sp.: five of these were M. bovirhinis, two were M. arginini and two were untypable. All of these animals yielded one or more of P. hemolytica, P. multiocida, infectious bovine rhinotracheitis virus or bovine virus diarrhea virus. Twenty-five of 29 animals in 16 lots yieled M. agalactiae subsp. bovis from lung tissues. The same organism was recovered from the arthritic joints of 12 of these animals. Eight of the 25 animals yielded no other pathogen and all of these had not received any treatment. Nine of the 25 M. agalactiae subsp. bovis positive animals also yielded one or more of P. hemolytica, P. multocida, Corynebacterium pyogenes or infectious bovine rhinotracheitis virus. Bacteriological and virological studies were not completed for the remaining eight of the 25 positive animals. In five lots of cattle which had not received medication for pneumonia and for arthritis only M. agalactiae subsp. bovis was recovered. Twenty-five grossly normal lungs obtained from normal cattle at the time of slaughter were cultured and all were negative. The possible role of M. agalactiae subsp. bovis in pneumonia and arthritis was discussed.  相似文献   

11.
We investigated the effect of vaccination of male beef calves (mean age+/-S.D.: 158+/-31 days) against bovine herpes virus (BHV-1 or IBR virus), bovine respiratory syncitial virus (BRSV), bovine viral diarrhea (BVD) virus and para-influenza (PI(3)) virus on the incidence of respiratory disease during the first forty days after weaning and entering a feed-lot in Portugal. In May 2003, Mertolenga, Preta and mixed-breed calves from 10 different beef herds, were systematically assigned (by order of entrance in a chute) to two treatment groups, before moving to a common feed-lot. One hundred and twenty five male calves were vaccinated with a quadrivalent vaccine (Rispoval 4) and revaccinated after 21-27 days while 148 herdmates were injected with saline (0.9% NaCl) on the same occasions. The incidence and severity of clinical cases of "bovine respiratory disease" (BRD) were evaluated every day during the first 40 days after entering the feed-lot. Morbidity (3% vs. 14%) and mortality (0% vs. 4%) due to BRD were significantly lower in the vaccinated group. Ten days after revaccination, the calves were treated with an antimicrobial - ending the study - after an outbreak of BRD caused a high incidence of disease in the non-vaccinated group. In conclusion, our results showed that Rispoval 4, a quadrivalent vaccine against respiratory viruses, under field conditions, reduces morbidity and mortality due to BRD in beef calves after weaning.  相似文献   

12.
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13.
The etiological agents involved in a bovine respiratory disease (BRD) outbreak were investigated in a dairy heifer calf rearing unit from southern Brazil. A battery of PCR assays was performed to detect the most common viruses and bacteria associated with BRD, such as bovine viral diarrhea virus (BVDV), bovine respiratory syncytial virus (BRSV), bovine alphaherpesvirus 1 (BoHV-1), bovine coronavirus (BCoV), bovine parainfluenza virus 3 (BPIV-3), Mannheimia haemolytica, Pasteurella multocida, Histophilus somni, and Mycoplasma bovis. Bronchoalveolar lavage fluid (BALF) samples were taken from 21 heifer calves (symptomatic n = 15; asymptomatic n = 6) that, during the occurrence of the BDR outbreak, were aged between 6 and 90 days. At least one microorganism was detected in 85.7 % (18/21) of the BALF samples. Mixed infections were more frequent (72.2 %) than single infections (27.7 %). The interactions between viruses and bacteria were the most common in coinfections (55.5 %). The frequencies of BRD agents were 38.1 % for BRSV, 28.6 % for BVDV, 33.3 % for BCoV, 42.85 % for P. multocida, 33.3 % for M. bovis, and 19 % for H. somni. BoHV-1, BPIV-3, and M. haemolytica were not identified in any of the 21 BALF samples. Considering that BALF and not nasal swabs were analyzed, these results demonstrate the etiological multiplicity that may be involved in BRD outbreaks in dairy calves.  相似文献   

14.
An enzyme linked immunosorbent assay (ELISA) was applied to the detection of serum antibodies against infectious bovine rhinotracheitis (IBR), parainfluenza-3 (PI3), adenovirus type 3 (adeno 3) and bovine respiratory syncytial (BRS) viruses. Paired serum samples from calves vaccinated with live attenuated virus vaccines were tested. The ELISA compared favorably with the virus neutralization test for detecting serologic responses to IBR, BRS, and adeno 3 viruses or with the hemagglutination inhibition test for PI3 virus. The simplicity, sensitivity and rapidity of the ELISA test makes it a useful tool for immunological studies with respiratory viruses.  相似文献   

15.
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16.
Diseases and pathogens associated with mortality in Ontario beef feedlots.   总被引：1，自引：0，他引：1  
This study determined the prevalence of diseases and pathogens associated with mortality or severe morbidity in 72 Ontario beef feedlots in calves that died or were euthanized within 60 days after arrival. Routine pathologic and microbiologic investigations, as well as immunohistochemical staining for detection of bovine viral diarrhea virus (BVDV) antigen, were performed on 99 calves that died or were euthanized within 60 days after arrival. Major disease conditions identified included fibrinosuppurative bronchopneumonia (49%), caseonecrotic bronchopneumonia or arthritis (or both) caused by Mycoplasma bovis (36%), viral respiratory disease (19%), BVDV-related diseases (21%), Histophilus somni myocarditis (8%), ruminal bloat (2%), and miscellaneous diseases (8%). Viral infections identified were BVDV (35%), bovine respiratory syncytial virus (9%), bovine herpesvirus-1 (6%), parainfluenza-3 virus (3%), and bovine coronavirus (2%). Bacteria isolated from the lungs included M. bovis (82%), Mycoplasma arginini (72%), Ureaplasma diversum (25%), Mannheimia haemolytica (27%), Pasteurella multocida (19%), H. somni (14%), and Arcanobacterium pyogenes (19%). Pneumonia was the most frequent cause of mortality of beef calves during the first 2 months after arrival in feedlots, representing 69% of total deaths. The prevalence of caseonecrotic bronchopneumonia caused by M. bovis was similar to that of fibrinosuppurative bronchopneumonia, and together, these diseases were the most common causes of pneumonia and death. M. bovis pneumonia and polyarthritis has emerged as an important cause of mortality in Ontario beef feedlots.  相似文献   

17.
Bovine respiratory disease (BRD) has been identified as the most significant infectious disease of feedlot cattle in eastern Australia.1 Bovine respiratory disease causes economic loss due to medication costs, mortalities, excessive feed inputs associated with increased time on feed, reduced sale prices and associated labour costs. Bovine respiratory disease is a complex multifactorial condition with multiple animal, environmental and management risk factors predisposing cattle to illness. A range of microorganisms are implicated in BRD with at least four viral and five bacterial species commonly involved individually or in combination. The viruses most commonly associated with BRD in Australia are bovine herpesvirus 1 (BHV1), bovine viral diarrhoea virus (BVDV or bovine pestivirus), bovine parainfluenza 3 virus (PI3) and bovine respiratory syncytial virus (BRSV). More recently, bovine coronavirus has been identified as a potential viral contributor to BRD in Australia.2 A number of bacterial species have also been recognised as important to the BRD complex; these include Mannheimia haemolytica, Pasteurella multocida, Histophilus somni, Trueperella pyogenes and Mycoplasma bovis. Although one or more of the pathogens listed above can be isolated from clinical cases of BRD, there is no evidence that infection alone causes serious illness. This indicates that, in addition to specific infectious agents, other factors are crucial for the development of BRD under field conditions. These can be categorised as environmental, animal and management risk factors. These risk factors are likely to exert their effects through multiple pathways including reductions in systemic and possibly local immunity. For example, stressors such as weaning, handling at saleyards, transport, dehydration, weather conditions, dietary changes, comingling and pen competition might reduce the effectiveness of the immune system. Reduced immunocompetence can allow opportunistic infection of the lower airways with potential pathogens leading to the development of BRD. The objective of this paper is to critically review the evidence for management practices aimed at reducing the incidence of BRD in Australian feedlot cattle. Predisposing factors (Table 1) largely beyond the control of most feedlots, such as weather and exposure to respiratory viruses, are discussed separately, but these factors can generate indirect prevention responses that are discussed under the preventative practices categories. The current practices are classified as either animal preparation practices (Table 2) or feedlot management practices (Table 3).  相似文献   

18.
A bovine respiratory virus vaccination trial   总被引：1，自引：0，他引：1  
A respiratory virus vaccination trial was carried out in a commercial calf-rearing unit with a history of virus pneumonia. The effects of vaccination on the incidence of virus respiratory disease and growth rate were assessed. Forty-four bought-in calves were allocated to groups and treated as follows: A, unvaccinated controls; B, intranasal temperature-sensitive infectious bovine rhinotracheitis (IBR) vaccine at three and 10 weeks; C, intranasal temperature-sensitive combined IBR and parainfluenza-3 (PI3) vaccine at three and 10 weeks; D, intranasal temperature-sensitive combined IBR and PI3 vaccine at three and 10 weeks plus live attenuated bovine respiratory syncytial (BRS) virus vaccine intramuscularly at seven, 10 and 16 weeks. Two outbreaks of virus pneumonia occurred, one at three to four months of age associated with BRS virus and the other at four to five months of age with PI3 virus. During these outbreaks the incidence of pneumonia was lower and the number of days of elevated temperature and the number of treatments were significantly less in groups vaccinated against the associated virus. Despite these findings there were no significant differences between the growth rates of the groups either during the outbreaks of virus pneumonia or during the 10 month period to slaughter.  相似文献   

19.
The associations between herd bovine herpesvirus 1 (BHV-1) seroprevalence, along with other infectious and farm management factors with bovine respiratory disease (BRD) in dairy calves and heifers, were investigated. Serum samples from 103 dairy cattle herds were analyzed for antibodies against BHV-1, bovine respiratory syncytial virus (BRSV), bovine viral diarrhea virus (BVDV), and Mycoplasma bovis (M. bovis). A questionnaire was used to record herd management practices. A high occurrence of respiratory disease in unweaned calves was associated with low to moderate and high prevalence of BHV-1 among cows (OR=14.8, p=0.005 and OR=19.2, p=0.002, respectively) and positive BVDV status of a herd (OR=5.1, p=0.02). The presence of BVDV in a herd was related to a high incidence of respiratory disease in heifers 3-16 months old (OR=4.3, p=0.027). Based on the results of multiple correspondence analysis, holding youngstock separately from cows until pregnancy, introducing new animals and the activities of on-farm employees may contribute to a higher incidence of BRD.  相似文献   

20.
During 1983-85, 279 calves requiring treatment for bovine respiratory disease and 290 comparison (control) animals from 15 different groups of feedlot calves were bled on arrival and again at 28 days postarrival. Their sera were then analyzed for antibodies to seven putative respiratory pathogens. On arrival, the prevalences of indirect agglutination titers to Pasteurella haemolytica, P. haemolytica cytotoxin, Mycoplasma bovis and M. dispar were greater than 50%, the prevalence of titers to bovine virus diarrhea virus (BVDV) was approximately 40%, and the prevalences of titers to infectious bovine rhinotracheitis virus (IBRV), bovine respiratory syncytial virus (RSV) and parainfluenza virus type 3 (PIV3) were all below 25%. Seroconversion during the first month after arrival occurred in more than half the calves to P. haemolytica cytotoxin, PIV3 and RSV. Seroconversion of agglutination titers to P. haemolytica, Mycoplasma and BVDV occurred in about 40% of calves, and seroconversion to IBRV was infrequent (less than 5%). Initial titers were negatively correlated to subsequent titer changes within organism. Initial titers, and titer changes between organisms were essentially independent. Light calves had an increased risk of being selected for treatment for respiratory disease. Seroconversion to P. haemolytica cytotoxin, RSV and BVDV were predictive of respiratory disease cases, explaining approximately 69% of all respiratory disease cases in the feedlots. It was not possible to accurately predict weight gain or relapse from the serological data.  相似文献   

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