Mycoplasma bovis and otitis in dairy calves in the United Kingdom

Signs of severe otitis media in 20% of dairy calves on one farm were associated with Mycoplasma bovis infection, based on isolation from the external ear canal and nares. Affected calves seroconverted to M. bovis and no other significant bacteria were isolated. Infection was considered likely to have originated from cows in the milking herd based on evidence of seroconversion and detection of infection in a milk sample. M. bovis infection should be considered when investigating otitis problems in calves.     

The use of the enzyme-linked immunosorbent assay (ELISA) in serological diagnosis of Mycoplasma bovis in dairy cattle

Between December 1985 and March 1987 an enzyme-linked immunosorbent assay (ELISA) was used with 3774 sera to estimate the prevalence of antibodies to Mycoplasma bovis in sera from three age groups of cattle in four dairies in California and to test for possible associations between the presence of M. bovis antibodies and the age or breed of the cattle and the farm. Unadjusted and adjusted associations were evaluated using the -square test for associations and multiple logistic regression analysis, respectively.There was a tendency for the proportion of cattle seropositive for M. bovis to increase steadily and approximately linearly with age (p<0.05). There was also a statistically significant relationship bbetween a M. bovis seropositive test and being from Farm IV (p<0.05). Farm IV was the largest of the four dairies and this association may be due to the effect of herd size.These findings confirm the ubiquitous distribution of antibodies to M. bovis in dairy cattle in California and also support previous reports of herd size as an important factor in mycoplasmal mastitis.     

The efficacy of valnemulin (Econor) in the control of disease caused by experimental infection of calves with Mycoplasma bovis

Mycoplasma bovis infection was experimentally induced in groups of six young calves. A further group was uninfected and served as a control. Ten days after infection, medication with either enrofloxacin (Baytril, Bayer) or valnemulin (Econor, Novartis) was instituted via the milk replacer for a further 10 days, after which all calves were killed. Infection resulted in depression, pyrexia, inappetance and prominent respiratory signs. Arthritis occurred in two animals and two (unmedicated) animals died. At post-mortem examination extensive lesions were present in the lungs and M. bovis was re-isolated from infected unmedicated calves' lungs. Medication with either enrofloxacin or valnemulin resulted in a rapid diminution of clinical signs, restoration of appetite and reversal of weight loss. Isolation of Pasteurella multocida from the calves' lungs was suppressed by both medicaments. Valnemulin resulted in a more rapid reduction of clinical scores and eliminated M. bovis from the lungs more effectively than enrofloxacin.     

Outbreak of bovine clinical mastitis caused by Mycoplasma bovis in a North Italian herd

This report describes an outbreak of Mycoplasma bovis mastitis affecting 45 cows in a herd of 122 dairy cattle in Northern Italy. Clinically, the outbreak was characterized by agalactia, multiple swollen and painless quarters, high milk somatic cell count and unresponsiveness to conventional antibiotic therapy. M. bovis was isolated from the milk samples of all the 32 affected cows tested and from the mammary tissue of three affected cows that underwent necropsy. No other pathogens were isolated from these samples. Lesions in two of the necropsied cows were characterized by mild chronic suppurative mastitis and galactophoritis. The other necropsied cow showed a chronic necrosuppurative and pyogranulamaous galactophoritis, a condition not previously associated with M. bovis. M. bovis was detected immunohistochemically in the lumen of the affected mammary ducts suggesting that ascending infection via the teat canal was the likely route of transmission. No other intralesional pathogens were demonstrated microscopically.     

Bovine respiratory disease: efficacy of different prophylactic treatments in veal calves and antimicrobial resistance of isolated Pasteurellaceae

The present study was conducted to evaluate the efficacy of two prophylactic antibiotic treatments against bovine respiratory disease (BRD) in veal calves. In addition, the antibiotic susceptibilities of isolated Pasteurellaceae were tested. The calves were treated either on the day of arrival by a single administration of tulathromycin (group A, n = 20), by a peroral administration of chlortetracycline, sulphadimidine, and tylosin (group B, n = 20) for seven consecutive days, or were not prophylactically treated (group C, n = 19). On the first day of clinically diagnosed BRD, transtracheal lavage samples were obtained prior to therapeutic treatment and were subsequently cultured. Pasteurellaceae isolates were tested for their susceptibility to 12 antimicrobial agents by the determination of the minimal inhibitory concentrations. During the first 56 d after arrival, different calves in group A and B suffered from one episode of clinically diagnosed BRD while calves of group C experienced two episodes. The average daily weight gain during the same period was significantly lower in group C (0.89 ± 0.04 kg/d) than in the two prophylactically treated groups (1.14 ± 0.05 and 1.15 ± 0.04 kg/d for group A and B, respectively). The improved performance of groups A and B in comparison to group C could be related to a lower incidence of respiratory disorders during the first days after arrival in the prophylactically treated animals. No differences in the clinical efficacy were seen between the two tested prophylactic treatments. The most prevalent bacterial pathogens isolated (n = 79) were Pasteurella multocida (23% of isolated pathogens), Mycoplasma bovis (18%), and Mannheimia varigena (16%). For the isolated Pasteurellaceae, a high resistance pattern was observed to tylosin (83% of the tested P. multocida and 88% of the Mannheimia spp. isolates resistant) and tilmicosin (56% of the tested P. multocida isolates non-sensitive).     

致犊牛肺炎和关节炎牛支原体新疆株的分离与鉴定

自2010年7月以来,新疆北疆部分地区某些奶牛场犊牛陆续出现严重的肺炎和关节炎,为确定其病原,无菌采集8个牛场病死犊牛的肺脏和关节液,患病犊牛的血清和部分鼻拭子,病料接种筛选培养基,通过菌落形态观察、特异性PCR鉴定、生长抑制试验和血清学检测,确定牛支原体15株,其中7株牛支原体克隆测序,与PG45 OPP F基因同源性为97.32%~100.00%。牛支原体ELISA试剂盒检测92份血清显示,阳性率82.61%。结果表明,该地区奶牛场发病犊牛以牛支原体感染为主。     

Identification and Serological Specificity of a Polysaccharide Component from Mycoplasma bovis

Whole-cell lysate and proteinase K digest preparations of the Mycoplasma bovis type strain (American Type Culture Collection 25523) were compared using sodium dodecyl sulfate polyacrylamide gel electrophoresis. Coomassie blue staining for protein revealed approximately 50 bands for the lysate but only a single band for the digest. Silver staining for polysaccharide revealed at least 19 bands for the digest. Fourteen monoclonal antibodies (MAbs) were produced using a screening procedure with an M. bovis digest. On immunoblots of digests of four M. bovis strains, an almost identical profile was seen with each strain for all 14 MAbs but differences were evident between strains. One MAb, M1557, was used to analyse 17 M. bovis strains on immunoblots. Ten to 20 bands were observed with 16 of the 17 strains, and differences were apparent among all 16 strains. In an enzyme-linked immunosorbent assay, M1557 reacted with 16 of the 17 M. bovis strains, but did not react with any of 41 non-M. bovis organisms tested. Strong reactions were observed with the MAbs and M. bovis colonies in immunofluorescence. The M. boris polysaccharide and MAbs to this component may be useful for the development of diagnostic assays for this organism.     

一起牛感染支原体与多杀性巴氏杆菌的诊断与治疗

2022年5月甘肃省某肉牛养殖场的部分犊牛,先后出现以咳嗽、呼吸急促、流鼻涕等为主的呼吸道症状,并陆续出现牛只死亡的情况,现场调查及临床检查后初步怀疑为细菌性病原感染。为进一步确诊病原并对症治疗,现场采集症状明显牛只的鼻拭子,同时对病死牛只进行解剖观察,无菌采集肺组织进行实验室病原检测。使用TaqMan探针荧光定量PCR进行3种(牛支原体、牛多杀性巴氏杆菌及牛溶血性曼氏杆菌)牛呼吸道疾病病原核酸检测。结果显示,病死牛只肺脏病变较为明显,肺尖实质化严重,上端有脂肪样颗粒状病灶;鼻拭子及肺组织呈牛支原体和多杀性巴氏杆菌核酸阳性。结果表明,该牛场本次发病是由于感染了牛支原体和牛多杀性巴氏杆菌引起的。通过采取隔离治疗、紧急免疫、严格消杀等综合性防控措施后,该牛场病情逐步好转并恢复正常生产。     

Chronic pneumonia in calves after experimental infection with Mycoplasma bovis strain 1067: Characterization of lung pathology,persistence of variable surface protein antigens and local immune response

Background

Mycoplasma bovis is associated with pneumonia in calves characterized by the development of chronic caseonecrotic lesions with the agent persisting within the lesion. The purposes of this study were to characterize the morphology of lung lesions, examine the presence of M. bovis variable surface protein (Vsp) antigens and study the local immune responses in calves after infection with M. bovis strain 1067.

Methods

Lung tissue samples from eight calves euthanased three weeks after experimental infection with M. bovis were examined by bacteriology and pathology. Lung lesions were evaluated by immunohistochemical (IHC) staining for wide spectrum cytokeratin and for M. bovis Vsp antigens and pMB67 antigen. IHC identification and quantitative evaluation of CD4⁺ and CD8⁺ T lymphocytes and immunoglobulin (IgG1, IgG2, IgM, IgA)-containing plasma cells was performed. Additionally, expression of major histocompatibility complex class II (MHC class II) was studied by IHC.

Results

Suppurative pneumonic lesions were found in all calves. In two calves with caseonecrotic pneumonia, necrotic foci were surrounded by epithelial cells resembling bronchial or bronchiolar epithelium. In all calves, M. bovis Vsp antigens were constantly present in the cytoplasm of macrophages and were also present extracellularly at the periphery of necrotic foci. There was a considerable increase in numbers of IgG1- and IgG2-positive plasma cells among which IgG1-containing plasma cells clearly predominated. Statistical evaluation of the numbers of CD4⁺ and CD8⁺ T cells, however, did not reveal statistically significant differences between inoculated and control calves. In M. bovis infected calves, hyperplasia of bronchus-associated lymphoid tissue (BALT) was characterized by strong MHC class II expression of lymphoid cells, but only few of the macrophages demarcating the caseonecrotic foci were positive for MHC class II.

Conclusions

The results from this study show that infection of calves with M. bovis results in various lung lesions including caseonecrotic pneumonia originating from bronchioli and bronchi. There is long-term persistence of M. bovis as demonstrated by bacteriology and immunohistochemistry for M. bovis antigens, i.e. Vsp antigens and pMB67. The persistence of the pathogen and its ability to evade the specific immune response may in part result from local downregulation of antigen presenting mechanisms and an ineffective humoral immune response with prevalence of IgG1 antibodies that, compared to IgG2 antibodies, are poor opsonins.     

Effect of diet composition and slaughter weight on animal performance, carcass and meat quality, and fatty acid composition in veal calves

The effect of true milk use in the diet of Spanish Brown Swiss male calves on animal performance, carcass and meat quality, and fatty acids composition was studied. In experiment 1, the effect of milk intake [ad libitum continuous (ADLIB) feed vs. restricted 0.7 during 75 days followed by ad libitum feed (RESTR)] and slaughter endpoint (225 kg vs. 5 month) were studied. In experiment 2, ad libitum concentrate feeding [grain-fed (GF)] was compared with milk supplementation until slaughter [milk-fed (MF)] in calves slaughtered at 345 kg. As regards to milk intake, carcass weight and degree of fatness were higher in the ADLIB group (P<0.05). The RESTR group revealed a higher percentage of saturated fatty acids (P<0.05). In experiment 2, the MF group exhibited a higher fat percentage (P<0.05), lower press and cooking losses (P<0.05), and higher scores for tenderness and juiciness (P<0.05) than the GF group. The percentage of saturated fatty acids was higher in the MF group (P<0.05). The results suggest that true milk use in veal production could be an advantageous alternative in terms on production costs, animal performance, and carcass and meat quality.     

Serological Survey of Babesia bovis and Anaplasma marginale in cattle in Tete Province,Mozambique

A serological survey of bovine babesiosis and anaplasmosis in communal cattle was conducted in the northwestern province of Tete, Mozambique. Blood was collected from cattle ranging from 4 to 15 months old from randomly selected farms from six districts. Thirty-nine per cent of all 478 calves tested in Tete Province were seropositive to the ELISA for Babesia bovis antibodies and 63% of all calves were seropositive in the card agglutination test for Anaplasma marginale. Seroprevalence of B. bovis ranged from 22.8% in Tete City District to 48.1% in Angonia District. For A. marginale, it ranged from 34.4% in Angonia District to 87.3% in Moatize District. The dominant factor affecting seroprevalence for both haemoparasites was district and there was a trend for higher intensity of tick control to be associated with a higher seroprevalence of B. bovis and a lower seroprevalence of A. marginale. The obvious differences were the low prevalence of B. bovis in Tete City Council District and the low prevalence of A. marginale in Angonia District. The levels of exposure to B. bovis seen in our study are well below any that could be considered to be consistent with endemic stability, yet they are sufficiently high to ensure that clinical disease would be a risk. The seroprevalence of A. marginale, however, suggests that endemic stability with respect to this disease could exist in districts other than Angonia. There was no strong and consistent relationship between the intensity of control and the likelihood of seropositivity to either of the diseases.     

Development of an Immunobinding Assay with Monoclonal Antibodies to Diagnose Mycoplasma bovis in Semen

Veterinary Research Communications -     

Effects of the two production programs ‘Naturafarm’ and ‘conventional’ on the prevalence of non-perforating abomasal lesions in Swiss veal calves at slaughter

Non-perforating abomasal lesions are a considerable problem affecting more than half the population of veal calves. The objective of the present study was to assess the prevalence of pyloric and fundic abomasal lesions in Swiss veal calves at slaughter and to compare the occurrence of non-perforating abomasal lesions between two different production programs (‘Naturafarm’ and ‘conventional’). ‘Conventional’-production settings met the minimal standards as defined by the Swiss animal welfare legislation, whereas ‘Naturafarm’ production complied with increased animal welfare requirements. In order to identify risk factors for the development of abomasal lesions, information on management, housing, and feeding was obtained by a questionnaire. A total of 125 abomasa were randomly selected in one large abattoir. They were examined macroscopically, and the occurence of lesions in either the fundic or pyloric region of the abomasum was recorded separately. Animals raised in the ‘conventional’-production setting revealed a significantly higher prevalence of lesions in the fundic part. Factors significantly affecting the prevalence of non-perforating lesions in the fundic part were the ‘conventional’-production environment, including missing access to an outside pen, missing access to water and straw as the only roughage, feeding by bucket and the liquid milk by-product Protofit in combination with the powder Sprayfit.     

Expression of Mycoplasma bovis variable surface membrane proteins in the respiratory tract of calves after experimental infection with a clonal variant of Mycoplasma bovis type strain PG45

The pathomorphological findings and the expression and distribution of variable surface protein antigens (Vsp) of Mycoplasma (M.) bovis were characterised immunohistochemically in lungs of eight calves following inoculation with a Vsp A-expressing clonal variant of M. bovis type strain PG45. Within 48 h post inoculation (p.i.) an innate immune response dominated by macrophages and neutrophils develops. The monoclonal antibodies (mAbs) 1A1 and 1E5 detected M. bovis Vsp antigens in paraffin tissue sections of seven calves. Vsp antigens were widely distributed and were already present at day two p.i. within macrophages and other lung compartments. Taken together, the results demonstrate that the bovine is unable to eliminate M. bovis during the time period examined. Based on the different immunohistochemical labelling patterns obtained with the mAbs, the results also support the speculation that the in vivo variability of Vsps together with immunological factors may contribute to the chronicity of pulmonary disease.     

Biochemical Characterization of Mycoplasma bovirhinis,Mycoplasma dispar and Recent Bovine Isolates of Mycoplasma canis

The pattern and kinetics of substrate utilization by the type strains of Mycoplasma canis, M. bovirhinis and M. dispar and ten recent M. canis isolates from cattle were determined. Metabolism of a range of sugars and organic acids by M. dispar was detectable by measurement of oxygen uptake. Organic acids were not utilized by M. bovirhinis or M. canis, and there was no oxygen uptake during metabolism of glucose or other sugars, as monitored by a pH-change method. The M. canis strains varied in their ability to metabolize sugars; seven of the isolates from cattle had the distinctive ability to metabolize sucrose, and one isolate, plus the type strain (from a dog), metabolized N-acetylglucosamine. The M. bovirhinis strain metabolized maltose. However, all the test strains oxidized glycerol at high rates and with a high affinity. Oxidation of glycerol has been reported for other mycoplasmas from the bovine respiratory tract and leads to the production of hydrogen peroxide, a potential virulence factor.     

Hydrogen Peroxide Production by Mycoplasma bovis and Mycoplasma agalactiae and Effect of In Vitro Passage on a Mycoplasma bovis Strain Producing High Levels of H2O2

Hydrogen peroxide (H2O2) production and oxygen uptake during the oxidation of NADH and L-alpha-glycerophosphate (GP) by lysed cells was determined for the type and field strains of Mycoplasma bovis and M. agalactiae. NADH oxidation by all the strains showed variable production of H2O2 ranging from 0 to 1.21 mol/mol O2 taken up. All strains were unable to oxidize GP, showing absence of GP oxidase activity. Some strains were identified that produced relatively high levels of H2O2 (> 1.0 mol/ mol O2 taken up). In vitro passage of M. bovis strain 119B96 showed reduced H2O2 production: 0.52, 0.16, and 0.07 mol/mol O2 taken up after the 50th, 100th and 200th passages, respectively. SDS-PAGE analysis showed the loss of a protein band of 32 kDa after 50 passages. These preliminary studies show that not only does H2O2 production by potentially pathogenic Mycoplasma spp. vary in the field but also that similar alterations can be induced by passage in culture. In the latter case, at least in one M. bovis strain, this alteration has been shown by SDS-PAGE to be associated with a loss of specific protein production. Further study of these phenomena is essential background for the production of more efficient vaccines for mycoplasmas.     

Host differences in response to trickle infection with Fasciola gigantica in buffalo, Ongole and Bali calves

Progressive weight gain, faecal egg counts, packed cell volume, percent eosinophils in blood, serum antibody and serum levels of glutamate dehydrogenase and gamma-glutamyl transpeptidase were recorded in seven swamp buffalo (Bubalis bubalis), 7 Ongole (Bos indicus) and four Bali calves (Bos sundiacus) which were infected orally with 15 metacercariae of Fasciola gigantica twice weekly for 32 weeks. Similar observations were made on four buffalo, 4 Ongole calves and 3 Bali calves maintained fluke-free as controls. Flukes were counted at slaughter 36 weeks after initial infection. Mean daily weight gains of infected Bali (228 ± 100 (SD) g/day) and infected Ongole calves (328 ± 57 (SD) g/day) were lower (p = 0.026 and 0.067, respectively) than those of control calves (405 ± 107 (SD) g/day), but infected buffalo calves (379 ± 78 (SD) g/day) had similar weight gains to those of the controls (p = 0.57). Throughout the trial, faecal Fasciola egg counts in buffaloes were about one-fifth of counts of Ongole calves, and counts in Bali calves were intermediate. Ongole calves had three times the number of flukes at slaughter in their liver compared to buffalo and Bali calves, which had similar numbers. However, there was evidence that Bali calves had acquired a degree of resistance about 24 weeks after infection commenced and may have lost adult flukes as a consequence.     

Current perspectives on the diagnosis and epidemiology of Mycoplasma hyopneumoniae infection

Mycoplasma hyopneumoniae is the principal aetiological agent of enzootic pneumonia (EP), a chronic respiratory disease that affects mainly finishing pigs. Although major efforts to control M. hyopneumoniae infection and its detrimental effects have been made, significant economic losses in pig production worldwide due to EP continue. M. hyopneumoniae is typically introduced into pig herds by the purchase of subclinically infected animals or, less frequently, through airborne transmission over short distances. Once in the herd, M. hyopneumoniae may be transmitted by direct contact from infected sows to their offspring or between pen mates.The ‘gold standard’ technique used to diagnose M. hyopneumoniae infection, bacteriological culture, is laborious and is seldom used routinely. Enzyme-linked immunosorbent assay and polymerase chain reaction detection methods, in addition to post-mortem inspection in the form of abattoir surveillance or field necropsy, are the techniques most frequently used to investigate the potential involvement of M. hyopneumoniae in porcine respiratory disease. Such techniques have been used to monitor the incidence of M. hyopneumoniae infection in herds both clinically and subclinically affected by EP, in vaccinated and non-vaccinated herds and under different production and management conditions. Differences in the clinical course of EP at farm level and in the efficacy of M. hyopneumoniae vaccination suggest that the transmission and virulence characteristics of different field isolates of M. hyopneumoniae may vary. This paper reviews the current state of knowledge of the epidemiology of M. hyopneumoniae infection including its transmission, infection and seroconversion dynamics and also compares the various epidemiological tools used to monitor EP.     

A cross-sectional study of bluetongue virus and Mycoplasma bovis infections in dairy cattle: II. The association between a positive antibody response and reproduction performance

In a cross-sectional study to determine the possible relationship between a positive antibody test to bluetongue virus (BTV) or Mycoplasma bovis infections and reproductive performance of dairy cows, data were collected on 572 California dairy cows during December 1986 for analysis. Serum samples were tested using an enzyme-linked immunosorbent assay (ELISA). Data on reproduction variables were extracted from the individual cow sheets of the California Dairy Herd Improvement Association records and interfaced with the serological results for analysis.Similar data analyses for both BTV and M. bovis were performed to identify and quantitatively assess the association of the reproduction variables and each agent. These associations were evaluated unconditionally using the x ² for categorical variables and Student's t-test for continuous variables. Logistic regression analysis was used to determine if reproduction variables with significant unconditional associations remained significant when adjusted for the effects of possible confounding factors.Both the BTV and M. bovis ELISA antibody titres indicated exposure to the agents. The results of the multiple logistic regression analyses indicated that cows seropositive for BTV were significantly older at first calving (p<0.03). For M. bovis, seropositive cows were more likely to have longer intervals from calving to last service and longer intervals from calving to pregnancy diagnosis than seronegative cows (p<0.05). The other reproduction variables examined were not significantly associated with ELISA seropositivity.     

A cross-sectional study of bluetongue virus and Mycoplasma bovis infections in dairy cattle: I. the association between a positive antibody response and production efficiency

In a cross-sectional study of bluetongue virus (BTV) and Mycoplasma bovis (M. bovis) infections, a sample of 572 California dairy cows was tested for the presence of antibodies to answer the question: Is it possible to identify and to assess quantitatively the associations between positive antibody test and production? Serum samples collected from these cows during December 1986 were tested for the presence of antibodies to BTV and M. bovis using the enzyme-linked immunosorbent assay (ELISA). Data on milk production were extracted from individual cow sheets of the California Dairy Herd Improvement Association (DHIA) record-keeping system and interfaced with percentage ELISA results for analysis. Univariate and multivariate statistical analyses, using the X ² test for categorical variables or Student's t-test for continuous variables and multiple logistic regression respectively, were carried out to evaluate for possible associations between positive antibody tests to each agent and each production variable of interest. Complete data on all variables studied were obtained for 289 (50.5%) cows for M. bovis and 423 (74%) cows for BTV. For cows with complete data on all variables, estimates of the point prevalence of antibodies to BTV and M. bovis were 70.5% and 66.1%, respectively. Results of this study indicated that Guernsey cows were more likely to have a positive BTV test than Holstein cows and that cows in higher lactations were more likely to test positive to BTV ELISA than those in lower lactations (p<0.05). Because all cows except those on one farm were Holstein, our confidence in the effect of breed is limited. The association between lactation number and BTV seropositive test may be an age factor identified earlier in the study. For M. bovis, the results of the analysis indicated that seropositive cows were more likely to produce less milk, on a mature equivalent basis (OR_adj=0.96, p=0.034), and that they had less extended 305 day milk production potential (OR_adj=0.90, p<0.0001) than seronegative cows.