Skin sensitivity to tuberculins in cattle vaccinated against Johne's disease

Aim: To evaluate the efficacy of a dry-cow antibiotic preparation containing cloxacillin plus ampicillin in a formulation that gives a 10-week duration of action, in comparison to products containing cephalonium (10-week action) or cloxacillin alone (7-week action).

Methods: A total of 493 cows were selected from 6 spring-calving dairy herds in the Manawatu region of New Zealand, according to the criteria of the SAMM plan, to receive intramammary antibiotic therapy at the end of lactation (drying off). Cows were randomly allocated to receive 1 of the 3 dry-cow antibiotic products under investigation. Cows were examined twice during the dry period and twice daily during the first 10 days of their subsequent lactation for the presence of mastitis. Milk samples were collected from individual quarters at the time of drying off and at 7 and 28-35 days after calving, for determination of milk somatic cell counts (SCC). Bacteriology was carried out on milk samples taken from cows that developed mastitis during the first 10 days after calving.

Results: No cows developed mastitis during the dry period. Sixteen cows developed clinical mastitis within 10 days of calving; there was no difference in incidence between treatments. Streptococcus uberis was the most commonly isolated organism. Mean SCC on Day 7 were lower (p = 0.019) in cephalonium-treated quarters (189.9 ± 28.4 × 10³ cells/ml) than in cloxacillin-treated quarters (388.7 ± 71.2 x 10³ cells/ml); values in quarters receiving cloxacillin plus ampicillin were intermediate (252.0 ± 47.0 × 10³ cells/ml). SCC were similar between treatment groups on Day 28–35.

Conclusions: The use of a combination of cloxacillin plus ampicillin was effective for the prevention of mastitis during the dry- and peri-calving-periods in pastured dairy cattle.     

Evaluation of diagnostic tests for Johne's disease in young cattle

OBJECTIVE: To investigate the development of immune responses in calves experimentally and naturally infected with Mycobacterium paratuberculosis and to evaluate the potential for diagnostic tests to detect infected calves. DESIGN: Sequential testing of four treatment groups of calves over a 2 year period. PROCEDURE: Twenty-nine calves were allocated to four groups. Group D calves were orally dosed with M paratuberculosis, group N calves naturally exposed to M paratuberculosis, group V calves vaccinated for M paratuberculosis, and group C were control calves (not infected or vaccinated). Blood and faecal specimens were collected from each calf at monthly intervals to 18 months of age and then every 2 months until they were slaughtered between the ages of 21 and 29 months. Specimens were tested using absorbed EIA, IFN-gamma EIA and faecal culture. The infection status of the calves was confirmed by extensive histopathological examination and tissue culture. RESULTS: M paratuberculosis infection was confirmed in 10 calves, comprising six of eight orally dosed calves, three of five naturally exposed calves and one of nine vaccinated calves. The six artificially infected calves and one naturally infected calf were detected shedding M paratuberculosis in their faeces. Results with positive absorbed EIA were obtained from one artificially infected calf, one naturally infected calf and three vaccinated calves. All calves including controls had positive results on at least one occasion using the IFN-gamma EIA. In addition, seven calves had positive bovine tuberculosis results using the IFN-gamma EIA, even though bovine tuberculosis has been eradicated from Australia. CONCLUSION: Detection of M paratuberculosis infection in young cattle continues to be difficult using current tests.     

Financial effect of bovine Johne's disease in beef cattle herds in Australia

Objective To assess the financial effect of programs for controlling bovine Johne's disease (BJD) in beef herds. Design A spreadsheet simulation model of a self‐replacing beef herd in south‐eastern Australia selling 400‐kg steers at 15 months old. Methods The model calculated the monthly cash flow, and net present value (NPV) of cumulative cash flow, over 10 years. Four main control options were compared: (1) a base herd (no action to control the disease), (2) test and cull, and (3) partial and (4) total destocking. It was assumed that BJD was eradicated after 3 and 5 years with total and partial destocking, respectively, and not eradicated with a test and cull program. Scenarios were compared for both commercial and stud enterprises. Results If there was no discount on the sale price of cattle in commercial herds, deaths from BJD had to exceed 5% before the NPV of partial or total destocking was similar to taking no action to control the disease over a 10‐year period. When cattle sales incurred a 10% discount, deaths had to exceed 1% before the destocking strategies would break even after 10 years. Conclusion Control options for BJD should be carefully planned on an individual herd basis, as significant production and financial risks accompany destocking programs. Eradication will only be more profitable in the longer term, compared with living with the disease, when discounts on the sale of stock from infected herds are high. This can occur with the selling of store cattle or breeders. In stud herds, BJD will usually cause the total failure of the business.     

Johne's disease in sheep

Extract

Inoculation of susceptible laboratory animals with a suspension of kidney tissue is a widely used method of diagnosing leptospirosis in livestock and of isolating leptospiral serotypes. A recent experience has indicated a potential cause of failure which may not be generally realized in laboratories using this technique.     

A Bayesian evaluation of six diagnostic tests for foot-and-mouth disease for vaccinated and non-vaccinated cattle

The sensitivity and specificity of six ELISA tests for foot-and-mouth disease (FMD) to discriminate between sero-converted (for non-structural FMD virus proteins) and non-sero-converted cattle were evaluated for vaccinated and unvaccinated cattle. Since none of the tests could be considered as a proper reference test and for about half of the tested sera the true status (sero-converted or not for non-structural proteins, i.e. presence of antibodies) of the animals was unknown, a Bayesian analysis employing a latent class model was used that did not rely on the use of a reference test or gold standard. Prior information about prevalence for subsets of the data and specificity of the tests was incorporated into the analysis. The specificity of the six tests for vaccinated and non-vaccinated cattle ranged from 96 to 99%. For vaccinated cattle, one test stood out with an estimated sensitivity of 94% (95% CI from 89.8 to 98.1%). Second best for vaccinated cattle were two tests with estimated sensitivities of 85% (95% CI from 78.9 to 89.7%) and 92% (95% CI from 86.2 to 95.6%). For non-vaccinated cattle, the sensitivities of these three tests were around 97%. The remaining three tests showed lower estimated sensitivity for vaccinated cattle, ranging from 57 to 79%.     

Experimental paratuberculosis (Johne's disease)--studies on biochemical parameters in cattle

Ten male Holstein-Friesian calves naturally infected by Mycobacterium paratuberculosis were experimentally re-infected orally at an average of 17 days. Monthly measurements were conduced of the following activities, in the period between post infection days 160 and 400: total protein (TPR), albumin (ALB), cholesterol (CHOL), triglycerides (TRIG), Zn and Cu concentrations as well as sorbitol dehydrogenase, lactate dehydrogenase (LDH), alpha-hydroxybutyrate dehydrogenase (alpha-HBDH), gamma-glutamyltransferase, aspartate aminotransferase (AST), alanine aminotransferase (ALT), creatine kinase (CK), alkaline phosphatase and fructose-1,6-diphosphate aldolase (ALD). TPR, ALB, TRIG, and CHOL were reduced by day 400, in conjunction with disorders of digestion and absorption. Increased activities of CK, ALD, LDH, alpha-HBDH, AST and ALT primarily indicated damage to skeletal muscle and/or liver. Serum CK and ALD activities as well as TRIG and TPR concentrations may serve as aids to specific diagnosis of paratuberculosis, particularly in the advanced stage of the disease.     

4种ELISA检测奶牛O型口蹄疫免疫抗体的比较试验

口蹄疫(FMD)是由口蹄疫病毒引起的以感染偶蹄动物为主的急性、热性、高度传染性疫病,世界动物卫生组织(OIE)将其列为必须报告的动物疫病.我国规定为一类动物疫病.我国奶牛口蹄疫的防控,以免疫接种措施为核心,实行强制免疫政策,要求O型和Asia Ⅰ型疫苗免疫密度必须达100%,通过牛群整体免疫水平的提高来预防口蹄疫的感染和流行[1].     

沈阳市某乳业公司奶牛钙、磷、β-胡萝卜素盈缺状况检查

对沈阳市某乳业公司七个奶牛场牛群血中钙、磷、β-胡萝卜素含量进行抽检，从全群3，000多头成母牛中共抽检350头奶牛，其中包括84头高产奶牛、77头干奶牛、92头产后牛和97头有病牛。结果表明：全群牛血中钙、磷的平均含量偏低，血钙的最高值、平均值和最低值分别为3．32mmol／l、2．26 0．44mmol／l和1．53mmol／l，血磷的最高值、平均值和最低值分别为2．71mmol／l、1．72 0．51mmol／l和0．84mmol／l；血中钙、磷比例不当，其最大值、平均值和最小值分别为3．96：1．0、1．70：1．0和0．645：1．0：血中钙、磷含量乘积偏低，其最高值、平均值和最低值分别为63．74、48．20和24．50；血中β-胡萝卜素含量不足，其最高值、平均值和最低值分别为657μg／100ml、278．69 201.78μg／100ml和52μg／100ml，其中高产牛血中含量相对较高。     

Occurrence of Coxiella burnetii in Polish dairy cattle herds based on serological and PCR tests

The aim of the research was to assess the prevalence of antibodies to Coxiella burnetii in dairy cattle herds in Poland and to compare the results of real-time PCR and ELISA tests performed on bulk tank milk (BTM) samples. In total, 2635 serum samples collected from 969 dairy cattle herds from all provinces were tested using ELISA. Additionally, BTM specimens from 101 herds were analysed by ELISA and real-time PCR targeting IS1111 element. Presence of anti-C. burnetii antibodies was confirmed in 25.39% of serum samples in 237 herds (24.46%) and the herd-level seroprevalence in Voivodeships varied from 2.5% to 61.4%. Moreover, 46 (45.5%) of analysed bulk tank milk samples gave postive result in ELISA and microbial DNA was detected in 40 (39.6%) of tested herds. The comparative analysis of ELISA and real-time PCR results obtained for BTM samples using the chi-square test showed statistically significant relationship between results of both methods.     

宁夏固原市肉牛口蹄疫和布鲁氏菌病血清抗体检测与分析

[目的] 为了调查宁夏固原市肉牛口蹄疫和布鲁氏菌病的流行情况,[方法]通过采集74份不同月龄肉牛血清样本,采用酶联免疫吸附试验(ELISA)对2种疫病抗体进行检测和分析。[结果],抗体阳性率由高到低分别为A型口蹄疫(48.65%)、O型口蹄疫(43.24%)、布鲁氏菌病(12.16%)。混合抗体阳性率中主要以O型和A型口蹄疫混合抗体阳性率最高(58.54%)。O型口蹄疫在西吉县的阳性检出率最高(88.24%),彭阳县最低(6.67%);A型口蹄疫在西吉县阳性检出率最高(82.35%),彭阳县最低(26.67%);布鲁氏菌病在原州区阳性检出率最高(15.00%),泾源县和彭阳县未检出。从不同年龄来看,3种疫病均在＞12月龄的肉牛中阳性率最高,分别为O型口蹄疫69.23%、A型口蹄疫76.92%、布鲁氏菌病15.38%。[结论] 固原市各个县区肉牛养殖地区均出现2种病原感染的情况,以O型和A型口蹄疫混合感染为主。在肉母牛养殖过程中,应加强对以上病原的检疫并采取相应的防控措施。     

Expression of adhesion molecules on milk and blood lymphocytes from periparturient dairy cattle with Johne's disease

Twelve dairy cows infected with Mycobacterium avium subsp. paratuberculosis were monitored for lymphocyte subsets and expression of adhesion molecules on cells in blood and milk at parturition and at intervals up to 21 days post-partum. Using fluorescent antibody labeling of cells and analysis by flow cytometry, we determined percentages of T cell subsets (CD4+, CD8+, gammadelta+) and expression of adhesion molecules (CD62L, LFA-1, LPAM-1, and CD44) on cells from blood and milk of these cows. Significantly higher percentages of CD8+ cells were found in milk than in blood at all time points; there were no significant differences in percentages of CD4+ or gammadelta+ cells. CD62L, LFA-1, and LPAM-1 were expressed on a significantly higher percentage of all T cell subsets in milk than in blood at various times after parturition. No differences were seen in expression of CD44. Increased percentages of T lymphocytes expressing adhesion molecules in milk compared to blood suggest that a migratory population of cells is being selectively recruited to the mammary gland from the circulation.     

乳牛衣原体病灭活疫苗的研制

将免疫原性稳定的鹦鹉热衣原体SX5菌株灭活，加入油佐剂制备乳牛衣原体病灭活疫苗，并对疫苗的安全性进行了检测。用该疫苗对成年牛和犊牛进行了最小免疫量试验、效力试验和免疫持续期试验；结果表明，最小免疫量分别为3mL和5mL，平均免疫保护率达94．4％。免疫持续期达10个月。疫苗保存期试验表明，在4℃条件下可保存12个月。本动物安全试验和田间小试免疫证明，该疫苗安全性好，乳牛注射疫苗后饮食、产乳量及注苗部位没有明显的异常变化。     

Prevalence and distribution of paratuberculosis (Johne's disease) in cattle herds in Ireland

A simple random survey was conducted in Ireland during 2005 to estimate the ELISA-prevalence of paratuberculosis, commonly called Johne's disease (JD), in the cattle population. Serum samples were collected from all 20,322 females/breeding bulls over 12 months-of-age in 639 herds. All samples were tested using a commercially available absorbed ELISA. The overall prevalence of infected herds, based on the presence of at least one ELISA-positive animal, was 21.4% (95% CI 18.4%-24.9%). Herd prevalence levels amongst dairy herds (mean 31.5%; 95% CI: 24.6%, 39.3%) was higher than among beef herds (mean 17.9%; 95% CI: 14.6%-21.8%). However, the animal level prevalence was similar. The true prevalence among all animals tested, was calculated to be 2.86% (95%CI: 2.76, 2.97) and for animals >= 2 yrs, it was 3.30% (95%CI: 3.17, 3.43). For animals in beef herds, true prevalence was 3.09% (95%CI: 2.93, 3.24), and for those in dairy herds, 2.74% (95%CI: 2.59, 2.90). The majority of herds had only one ELISA-positive infected animal. Only 6.4% (95% CI 4.7%-8.7%) of all herds had more than one ELISA-positive infected animal; 13.3% (CI 8.7%-19.7%) of dairy herds ranging from two to eight ELISA-positive infected animals; and, 3.9% beef herds (CI 2.4%-6.2%) ranging from two to five ELISA-positive infected animals. The true prevalence of herds infected and shedding Mycobacterium avium subspecies paratuberculosis is estimated to be 9.5% for all herd types; 20.6% for dairy herds; and 7.6% for beef herds. If ELISA positive animals <2-years-of-age are excluded, the true herd prevalene reduces to: 9.3% for all herd types; 19.6% for dairy herds; and 6.3% for beef herds based on a test specificity (Sp) of 99.8% and test sensitivity (Se) (i.e., ability to detect culture-positive, infected animals shedding at any level) of 27.8-28.9%.     

肉牛口蹄疫灭活苗不同免疫程序免疫效果的比较

为了解肃南地区肉牛口蹄疫免疫动态,达到为本地区肉牛养殖制定科学口蹄疫免疫程序的最终目的.本文与2019年3月份采用随机抽样方法选取120头肉牛,分成了3组,分别采取不同免疫程序,根据免疫抗体检测水平的变化,选择免疫效果最佳的免疫程序.试验结果表明,第3组的口蹄疫A型、O型抗体水平最高.因此,本试验推荐肉牛场每年免疫3～...