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1.
Experimental immunisation of lambs against pneumonic pasteurellosis   总被引：1，自引：0，他引：1  
Methods of immunising lambs against pneumonic pasteurellosis, caused by several serotypes of Pasteurella haemolytica, were assessed in specific pathogen free lambs. Lambs were vaccinated intramuscularly with sodium salicylate extract (SSE) of P haemolytica, either alone or in combination with heat-killed organisms (HKO). SSE of P haemolytica type A1 protected vaccinated lambs against pneumonia resulting from challenge with the homologous serotype. SSE of type A2 also provided some protection but this was improved by vaccination with a combination of SSE and HKO.  相似文献   

2.
AIM: To describe temporal and spatial patterns of the prevalence of pneumonia in lambs in three regions of New Zealand, and determine effects on liveweight gain. METHODS: A longitudinal study was conducted in 1999- 2000 on 14 commercial sheep farms, five from the Southland region of the South Island, and five from the King Country and four from the Northland regions of the North Island. Pneumonia was known to be a problem in lambs on all farms selected. On each farm, 400 lambs were randomly selected at weaning and allocated at random to one of two groups (Groups I and II). Lambs in both groups were weighed at 4-weekly intervals. The extent of pneumonic lesions in lungs was scored visually at slaughter in 40 randomly selected lambs after each weighing (Group I). Lambs in Group II were selected for slaughter by the farm manager on a commercial basis of liveweight and body condition, then assessed for pneumonic lesions. RESULTS: Prevalence of extensive pneumonic lesions (>/=10% lung surface area affected) increased from December to March from 1.4 to 10.1% lambs in Southland (n=1,917), 1.2 to 25.7% in the King Country (n=1,831), and 4.7 to 21.4% in Northland (n=1,485). Overall, 42.3% of lambs in both groups had pneumonic lesions (n=5,233) and in 15.1% of these, >/=5% of the lung surface area was affected. Daily weight gain in the month prior to slaughter was reduced in lambs for which >/=20% lung surface area was affected in Group I (p<0.05) but not in Group II. CONCLUSIONS: The association between pneumonic lesions and reduced weight gain was highly significant in lambs from Group I, but not from Group II. Thus, pneumonia had a negative impact on weight gain, and selection by farmers of lambs for slaughter counteracted this association in lambs from Group II. CLINICAL RELEVANCE: Pneumonia occurs commonly as a subclinical disease in lambs in New Zealand. It has no public health significance and is not recorded at slaughter plants nor reported to farmer clients. Effects of the disease on daily weight gain of lambs is considerable and costly for lamb producers.  相似文献   

3.
Groups of 20 lambs were vaccinated with parainfluenza virus type 3 PI3 by the intranasal (I.N.) or intramuscular route (I.M.).Approximately 6 weeks later, vaccinated and non-vaccinated lambs were challenged sequentially with PL3, and Pasteurella haemolytica. At slaughter, 10 to 12 days after challenge, 65% of non-vaccinates and 45% of I.M. vaccinates had pneumonic lesions whereas lesions were not observed in any of the I.N. vaccinates.  相似文献   

4.
A study was undertaken to investigate the effects of the immune response induced by combined aerosol and parenteral vaccination on the lung lesions induced in calves by Pasteurella haemolytica AI. Twenty-four calves, twelve of which had been vaccinated with killed P. haemolytica by aerosol and subcutaneous injection in Freund's complete and incomplete adjuvant were challenged by intratracheal inoculation of live P. haemolytica. Serological response to vaccination was not marked but was best measured by the whole cell agglutination test or by indirect bacterial agglutination rather than by the passive haemagglutination test. Titres of vaccinates were positively correlated with the degree of pneumonic change following challenge while in nonvaccinated controls, titres were negatively correlated with lung lesions. These findings suggest the occurrence of an immunologically mediated hypersensitivity pneumonitis in the lungs of vaccinates and point to the potential efficacy of live bacterial aerosols for stimulation of protective immunity in pneumonic pasteurellosis.  相似文献   

5.
The effectiveness of an oil adjuvant vaccine (OAV) incorporating locally isolated strains of Pasteurella haemolytica type 7 and Pasteurella multocida types A and D was compared with that of Carovax (Wellcome Laboratories) in imported cross-bred lambs. The criterion of efficacy was the ability of the vaccines to reduce the extent of pneumonic lesions in vaccinated as against unvaccinated control lambs. The OAV produced at this Institute significantly reduced the lung lesions at P less than 0.05 level compared with its control group when challenged with P. haemolytica alone. However, the vaccine was unsatisfactory against P. multocida or combined P. multocida P. haemolytica challenge. Carovax did not produce any significant reduction in the lung lesions caused by P. haemolytica and/or P. multocida.  相似文献   

6.
The effectiveness of simultaneous administration of commercial Mycoplasma hyopneumoniae and Actinobacillus pleuropneumoniae vaccines was tested in an indoor commercial piggery which had experienced continuing respiratory-disease problems confirmed as due to both of these pathogens. Piglets were randomly assigned in equal numbers to vaccination and control groups, and each vaccine was administered at a separate site to assigned piglets at two and four weeks of age. Live weight of vaccinates immediately prior to slaughter was 2.49 kg higher (p = 0.04) than for controls at equal mean slaughter age of 132 days. Average daily gain (ADG) from 16 weeks to slaughter of vaccinates was also significantly higher (33 g/day) than in controls (p = 0.05). Daily gain was not significantly different in younger age groups. Active enzootic pneumonia lesions were more likely in control than in vaccinated pigs. There were no significant differences between vaccination groups with regard to severity of pleurisy or presence of pleuropneumonia lesions at slaughter. Log-linear modelling was used to test the statistical association between vaccination, enzootic pneumonia lesions, pleurisy lesions and pleuropneumonia lesions. It showed a reduction in the severity of enzootic pneumonia lesions for vaccinated pigs, and the presence of pleuropneumonia lesions increased the likelihood of pleurisy lesions. No other association was significant, and no evidence of synergy between the vaccines in influencing lesion severity for pleuropneumonia was detected (within the limitations set by the trial design).  相似文献   

7.
The liveweight gains and carcass weights of 40 lambs grazed under pastoral conditions were compared with those of a similar group with chronic non-progressive pneumonia which had been induced by intranasal inoculation of an aerosol of homogenised pneumonic lung at about 120 days of age. Half the lambs from each group were killed 30 days post-inoculation following rotational grazing on high quality pasture. At this time the pneumonic lambs had a mean liveweight gain of 1.74 kg less than the controls. The remainder were slaughtered at 60 days, when drier conditions prevailed, by which time the difference in mean liveweight had increased to 2.19 kg. During the second period, four of the severely affected lambs lost weight. A significant linear relationship was found between liveweight gain and the extent of the pneumonic lesions which indicated that a reduction of nearly 1 kg/month could be expected for every 10% of the lung surface area affected. Carcass weights were reduced by a mean of 1.5 kg over the 60-day period, 1.39 kg of which occurred in the first 30 days.  相似文献   

8.
The liveweight gains and carcass weights of 40 lambs grazed under pastoral conditions were compared with those of a similar group with chronic non-progressive pneumonia which had been induced by intranasal inoculation of an aerosol of homogenised pneumonic lung at about 120 days of age. Half the lambs from each group were killed 30 days post-inoculation following rotational grazing on high quality pasture. At this time the pneumonic lambs had a mean liveweight gain of 1.74 kg less than the controls. The remainder were slaughtered at 60 days, when drier conditions prevailed, by which time the difference in mean liveweight had increased to 2.19 kg. During the second period, four of the severely affected lambs lost weight. A significant linear relationship was found between liveweight gain and the extent of the pneumonic lesions which indicated that a reduction of nearly 1 kg/month could be expected for every 10% of the lung surface area affected. Carcass weights were reduced by a mean of 1.5 kg over the 60-day period, 1.39 kg of which occurred in the first 30 days.  相似文献   

9.
Mycoplasmas and other micro-organisms are recorded from a pig herd originally derived by hysterectomy. Complement fixation tests were positive for Mycoplasma hyopneumoniae 20 months after the first hysterectomy. Following a marked increase in pneumonic lesions found at slaughter, and after modifying the culture medium M hyopneumoniae was isolated. The principal micro-organism associated with this mycoplasma was Pasteurella multocida.  相似文献   

10.
The effect of maternal antibody to the toxin of Corynebacterium pseudotuberculosis, produced by caseous lymphadenitis (CLA) in ewes or by vaccinating ewes before lambing, on the efficacy of vaccination against CLA in their lambs was examined. Lambs were allocated to treatments according to either the vaccination history of their dam or level of CLA toxin antibody of their dam. They were vaccinated twice using 2 different inoculation regimes and then artificially infected with CLA organisms. The number of lambs with CLA lesions was assessed at slaughter. In one experiment high levels of CLA toxin antibody activity in ewes were associated with decreased efficacy of CLA vaccination in their lambs, when lambs were vaccinated at 2 and 8 weeks or 8 and 14 weeks of age. In a second experiment the efficacy of lamb vaccination at 8 and 12 weeks, but not at 14 and 18 weeks of age, was decreased. In sheep flocks with a high prevalence of CLA, vaccinating lambs against CLA at less than 10 weeks of age may not produce optimum protection against CLA in lambs. There was no difference in infection rate between lambs from vaccinated and unvaccinated ewes. However, vaccination of lambs at 2 and 8 wks was less effective that vaccination at 8 and 14 weeks, probably due to reduced immunocompetence in young lambs. In sheep flocks where significant numbers of lambs receive their primary vaccination at less than 3 weeks of age vaccination programmes to control CLA in lambs may be less effective.  相似文献   

11.
Conflicting findings exist among studies on the effect of pneumonia on growth in pigs. We determined the extent of pneumonia in market-weight pigs by use of an objective, volumetric method and linear regression analyses of mean daily gain and days-to-slaughter weight on the percentage of pneumonic lung. In a range of extent of pneumonia between 1.33 and 70.44%, a 10% increase in the volume of pneumonic lung was associated with a decrease in mean daily gain by 41.1 g and a 16.7-day increase in number of days to a slaughter weight of 104.5 kg.  相似文献   

12.
A total of 36 calves were used in three experiments to test the efficacy of a potassium thiocyanate extract of Pasteurella haemolytica in protecting against experimental pneumonia. In each of experiments A and B, 12 calves were divided into three equal groups. The first group was vaccinated with an aerosol of a potassium thiocyanate extract twice, two weeks apart; the second group was vaccinated subcutaneously once only with the same extract. The third group of calves in both experiments remained as unvaccinated controls. In experiment C, six calves were vaccinated intramuscularly and six were left as controls. Approximately one month after vaccination all calves were challenged with an aerosol of bovine herpesvirus 1 (isolate 108) followed in 4 d by an aerosol of P. haemolytica type A1 (the same strain from which the potassium thiocyanate extract had been made). Varying degrees of protection against subsequent development of experimental pneumonic pasteurellosis in cattle were seen in vaccinated calves as compared to control calves in these experiments. The results indicate that protection of cattle against pneumonic pasteurellosis may prove possible with a sub-cellular extract of P. haemolytica.  相似文献   

13.
Ten pregnant gilts were divided into two groups of five and one group was vaccinated at 80 and 95 days of pregnancy with a commercial bacterin containing Haemophilus parasuis serovars 2, 3 and 5. Half the piglets born to each group of gilts were vaccinated at seven and 21 days of age with the same bacterin, and one week after they were weaned at five weeks, all the piglets were inoculated intratracheally with 10(6) colony-forming units of Hparasuis serovar 5. At slaughter, a significantly smaller percentage of the lungs of the pigs born to the vaccinated gilts was affected by pneumonic lesions, and significantly fewer of them had arthritic joint changes. The average daily liveweight gain of the pigs born to the vaccinated gilts was significantly greater than that of those born to the unvaccinated gilts, but the vaccination of the piglets had no effect. There was no significant difference between the feed conversion ratios of the four groups of piglets, and none between the average times they took to reach slaughter weight. The pigs born to the vaccinated gilts had higher ELISA titres to Hparasuis than those born to the unvaccinated gilts.  相似文献   

14.
The objectives of the present study were to compare Mycoplasma hyopneumoniae (Mh) colonization and serologic status on Mh vaccinated and non-vaccinated sows and to assess the effect of sow vaccination on colonization and serologic status of their piglets at weaning as well as presence of enzootic pneumonia (EP) lung lesions at slaughter. Fifty sows (25 vaccinated and 25 unvaccinated) as well as five of their piglets were included in the study. Blood samples and nasal swabs from sows at 7 weeks pre-farrowing and 1 week post-farrowing and from piglets at 3-4 weeks of age were taken. Nasal swabs and sera were tested by a nested polymerase chain reaction (nPCR) to detect Mh DNA and by an enzyme-linked immunosorbent assay (ELISA) test to detect antibodies to the pathogen, respectively. Finally, at 23 weeks of age, pigs were sent to the slaughter where the extension of EP-compatible gross lesions was assessed. Vaccination with two doses of Mh vaccine resulted in a significantly higher (p<0.05) percentage of seropositive sows than in the non-vaccinated group at 1 week post-farrowing. On the contrary, no statistical significant differences were found in the number of nasal nPCR positive sows among different treatments (p>0.05). At 3-4 weeks of age, a significantly higher percentage (p<0.001) of seropositive piglets came from vaccinated than from non-vaccinated sows. Although the number of Mh infected piglets coming from non-vaccinated sows was higher than the one from vaccinated sows, the difference was not statistically significant (p>0.05). Overall, piglets from vaccinated sows had a significant lower (p<0.05) mean of EP-compatible lung lesions (1.83+/-2.8) than piglets from non-vaccinated sows (3.02+/-3.6). Under the conditions described in this study, sow vaccination did not affect sow or piglet colonization but increased the percentage of seropositive sows and piglets at weaning and reduced significantly the mean EP-compatible lung lesion scoring at slaughter.  相似文献   

15.
The experimental induction of pneumonic pasteurellosis in groups of conventionally reared lambs by 8 serovars (A1, A2, A6, A7, A8, A9, T10, and A11) and untypable (UT) strains of Mannheimia haemolytica (Mh) were examined and compared. The groups of lambs were inoculated intratracheally with 1.4 x 10(8) +/- 0.6 x 10(8) (mean +/- SD) colony-forming units of the Mh serovars or UT isolates in the 6-hour log phase of growth. The variables measured as indicators of disease severity were clinical score, percentage lung consolidation and microbiological re-isolation. The clinical parameters for each group were computed daily for 6 days post infection and the lambs which died were necropsied while the remaining lambs were killed on day 7 pi and the extent of lung consolidation was measured. Clinically, the mean scores for the M. haemolytica serovars were A1 (6.1), A2 (18.8), A6 (0.5), A7 (17.4) and A9 (8.5). The mean percent lung lesion scores for M. haemolytica serovars were A1 (12.5), A2 (66.3), A6 (5.0), A7 (51.3), A9 (33.8) and A11 (2.5). The percent mean pneumonic lung lesions recorded for groups inoculated with A2, A7 and A9 were significantly (P < 0.05) higher than the extent of lung lesions in the other groups. A statistically significant correlation was observed between clinical scores and the severity of the lung lesions (r = 0.96, P < 0.01). High titres of M. haemolytica were recovered from lung lesions, with 10 to 100 times the number of organisms inoculated being present in the lung lesions of lambs inoculated with serovars A2 and A7. These data indicate that although M. haemolytica serovars A1, A2, A6, A7, A9 and A11 are important primary lung pathogens of lambs, serovars A2, A7, and A9 are to be regarded as highly virulent strains that have a greater predilection than the other serovars for causing pneumonia in lambs.  相似文献   

16.
Pigs in three specialized fattening herds were studied with respect to the effect of infection with Mycoplasma hyopneumoniae on weight gain. Individual pigs were weighed four times at 4-week intervals during the fattening period and their daily weight gain over the rearing period was calculated. A blood sample was collected on each weighing occasion and analysed for the presence of antibodies to M. hyopneumoniae. The lungs of the principals were inspected at slaughter and the extent of pneumonic lesions was registered by a specially developed technique that has been proven to warrant a high degree of repeatability. No serum antibodies to M. hyopneumoniae were detected in one of the herds, and no pneumonic lesions were recorded at slaughter in that herd. In the other two herds, the prevalence of pigs with serum antibodies to M. hyopneumoniae increased from 6 to 54% and from 31 to 81%, respectively, during the fattening period. The prevalence of pneumonic lesions at slaughter in these herds was higher the later the pigs seroconverted. On the other hand, the extension of the lung lesions tended to be higher among pigs that seroconverted early during the rearing period. Infections with M. hyopneumoniae acquired early during the rearing, presumably strengthened by secondary infections and environmental errors, was found to decrease the daily weight gain of the pigs. However, even non-complicated M. hyopneumoniae infections acquired late in the fattening period were associated with reduced daily weight gain. That growth reduction was estimated to be at least 60 g (about 6%) after adjusting for herd, pen, initial weight and sex.  相似文献   

17.
An inactivated vaccine prepared from broth culture supernatant of Mycoplasma hyopneumoniae with an aluminum adjuvant was evaluated in three herds (herd A: specific pathogen-free herd, herd B: high health status herd with no clinical signs of respiratory infection, herd C: low health status herd with serious epidemiological and economical problems). A total of 212 pigs from the three herds were divided into two groups. One group was injected twice with the vaccine at 4-week intervals and the other was a control group. No adverse reactions were noted following the vaccinations either systematically or locally in any of the vaccinated pigs from any of the herds. In herd A, the vaccination provided antibody response within 4 weeks after the second vaccination and antibody responses continued for more than 12 weeks. In herds B and C, the number of pigs with lung lesions, mean percentage of lung lesions, and the numbers of M. hyopneumoniae recovered from pigs at slaughter in the vaccinated group were significantly (P < 0.05) reduced compared to the control group. Furthermore, vaccination resulted in improved average daily weight gain (ADG), improved feed conversion ratio (FCR), and improved days to market weight in herd C, whereas no difference in growth performance was shown in herd B. It is suggested that the inactivated vaccine prepared from broth culture supernatant of M. hyopneumoniae is effective in reducing clinical signs and lung lesions. Also, vaccination resulted in improved growth performance in herds where clinical signs and economic losses were significant.  相似文献   

18.
A group of 85 commingled feeder pigs was fed on a totally confined feeding floor until slaughter. Mean daily weight gain was calculated for each pig. At slaughter, the nose of each pig was cross-sectioned and scored for conchal atrophy by use of 2 methods. One method ascribed a score based on a linear measurement of the distance between the ventral scroll of the ventral conchae and the ventral floor of the nasal cavity. The other method ascribed a score based on a subjective evaluation of the degree of conchal degeneration according to previously published guidelines. The amount of pulmonary consolidation attributable to pneumonia was also estimated for each pig. Association was not found between growth rate and conchal atrophy, as determined by linear measurement scores. A negative correlation existed between growth rate and conchal atrophy, as determined by subjective evaluation scores. Pigs with extensive pneumonic lesions (consolidation of 20 to 30% of total lung volume) grew slower than pigs with milder pneumonic lesions. Results of this study indicate that subjective evaluation scores of conchal atrophy may be more useful in predicting growth rate than are linear measurement scores.  相似文献   

19.
Three experiments were performed to evaluate the immunogenic potency of a soluble fraction of Pasteurella haemolytica against pneumonic pasteurellosis in calves. A soluble antigen was extracted by a 2.5% saline solution from P. haemolytica. Weaned Holstein bull calves, seronegative for infectious bovine rhinotracheitis virus ( IBRV ) and the pasteurella antigen, were vaccinated either by repeated subcutaneous (SC) vaccination, or by exposure 3 times to the aerosol of P. haemolytica antigen. Challenge exposure to aerosol of P. haemolytica was preceded by infection with IBRV , or in experiments 2 and 3, the virus exposures were combined with a stress treatment. The lung lesions were examined at necropsy 3 to 8 days post infection. In the first experiment, all the vaccinated calves produced specific antibody response to the pasteurella antigen, and none of the calves including controls showed significant lesions in the lung. In the second experiment 2 aerogenically vaccinated calves had no lesions. One of the two SC-vaccinated calves had mild consolidated lesions. Two control calves, one of which died 3 days following the challenge, developed severe fibrinous pneumonia with consolidation of 50% or more of the lung surfaces. P. haemolytica was isolated only from the 2 control animals. In the third experiment, 2 of the 3 control calves developed moderate to severe consolidation, but P. haemolytica was isolated only from one of them. Two of the three aerosol-vaccinated calves also developed significant lesions and one of them yielded the bacteria from the lung. Three SC-vaccinated calves had slight lesions and the organism was not isolated from their lungs. The results did not consistently indicate an immunogenic potential of the soluble antigen against P. haemolytica-related pneumonia. The effect of stress on the pathogenesis of bovine viral pneumonia and correlation between pneumonic lesions and antibacterial resistance in situ are discussed.  相似文献   

20.
Specific pathogen free lambs were exposed to an aerosol of Pasteurella haemolytica. Ten lambs vaccinated with an adjuvanted killed P haemolytica vaccine and nine units of P haemolytica administered in an aerosol. Pneumonia histologically indistinguishable from natural pneumonic pasteurellosis occurred in one vaccinated lamb and in four control lambs.  相似文献   

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