Investigations on the Prevalence of Bovine Tuberculosis and Brucellosis in Dairy Cattle in Dar es Salaam Region and in Zebu Cattle in Lugoba Area,Tanzania

A study between August 1995 and December 1997 included 343 dairy cattle on 20 farms in the Dar es Salaam region and 2289 zebu cattle on 39 bomas in the Lugoba area (coast region). The aim was to establish the prevalence of bovine tuberculosis (Mycobacterium bovis) and bovine brucellosis (Brucella abortus). In the single intradermal tuberculin test (SIT), 0.9% (3/343) of the animals in Dar es Salaam tested positive and 1.2% (4/343) were doubtful. Positive reactors were found in 10% (2/20) of the farms. In the Lugoba area, 0.6% (14/2206) were positive and 6.8% (149/2206) doubtful, positive cases being found in 21% (8/39) of all bomas. In the slow agglutination test (SAT) for B. abortus, 14.1% (48/341) of the serum samples reacted positively in Dar es Salaam and 2.3% (8/341) were doubtful. Positive SAT reactors were identified on 25% (5/20) of the dairy cattle farms. In the Lugoba area, 12.3% (273/2221) proved to be positive SAT reactors and doubtful reactions were observed in 2.9% (64/2221). SAT-positive animals were detected on 87% (34/39) of all bomas. The prevalence in single herds in Dar es Salaam varied from 4.3% to 5.3% for the SIT and from 2.2% to 50% for the SAT. The prevalence in single herds in Lugoba area was between 1.1% and 2.9% for SIT and from 1.4% up to 62.1% for SAT. The two cattle populations differed significantly (p<0.001) in the prevalence of both bovine tuberculosis and bovine brucellosis. Two cows that were positive reactors were slaughtered and subjected to post-mortem examination, and organ samples were bacteriologically cultured. The occurrence of Mycobacterium tuberculosis was confirmed by polymerase chain reaction (PCR) in both cows.     

Evaluation of the Abbott LCx Mycobacterium Tuberculosis Assay for Direct Detection of Mycobacterium Bovis in Bovine Tissue Samples

The commercial LCx amplification assay, usually employed to detect the Myocobacterium tuberculosis complex in respiratory specimens, was evaluated by comparing the results it gave with those obtained using Löwenstein-Jensen solid medium and pathological findings on 55 lymph nodes from cattle with positive and 10 lymph nodes from cattle with negative skin tests for tuberculosis. Fifty-three cultures (51 and 2, respectively) were positive for M. bovis, while the results for the LCx assay and the histological method were positive in 48 (45, 3) and 24 (20, 4) samples, respectively. None of the samples from cattle from certified tuberculosis-free herds were positive by any of the procedures. The results obtained with the LCx assay, compared with the culture procedure, regarded as the gold standard among the diagnostic techniques, gave a specificity of 91.6% and sensitivity of 90.5%. Although the sensitivity of LCx was suboptimal, DNA of M. bovis was detected in 81.8% of the skin test-positive animals. Amplification techniques could provide a rapid and reasonably reliable tool for detecting bovine tuberculosis.     

Comparison between Comparative Tuberculin and Gamma-Interferon Tests for the Diagnosis of Bovine Tuberculosis in Ethiopia

A study to determine and compare the sensitivities and specificities of the comparative cervical tuberculin (CCT) and gamma-interferon (IFN-) tests for the diagnosis of bovine tuberculosis was conducted on 30 zebu oxen. The results of the tests were compared with the presence of acid-fast bacilli found by bacteriological culturing and histopathological examinations. The sensitivity and specificity of CCT test were found to be 90.9% and 100%, respectively. Those of the commercial IFN- test were determined to be 95.5% and 87.7%, respectively. No significant differences were found between the sensitivities (Yates' corrected ² = 0.32; p = 0.57) or the specificities (Yates' corrected ² = 2.54; p = 0.11) of the two tests. Furthermore, a positive correlation (r = 0.76) was recorded between the increase in skin thickness following injection of bovine purified protein derivative (PPD) and the optical density in the gamma-interferon assay with bovine PPD. On the other hand, the correlation (r = 0.47) between the change in skin thickness following injection of avian PPD and the optical density in the gamma-interferon assay with avian PPD was relatively weak. On the basis of this preliminary investigation, it was concluded that the choice between the two tests depends on their cost and simplicity and on livestock management and time factors rather than on their respective diagnostic value.     

Tuberculosis in deer: perceptions, problems and progress

Since the emergence of deer farming as an alternative farming enterprise over the past 30 years, there has been an increasing awareness of the potential threat posed by tuberculosis (TB) to domesticated deer. TB, caused by Mycobacterium bovis, has been found in deer in every country involved with deer farming. Different types of TB control policies, which vary from whole-herd depopulation to selective testing and slaughter of reactor animals, have been implemented. Extensive research has been carried out, incorporating modern microbiological and immunological concepts and advanced molecular methodologies, to find new solutions for the eradication of TB from domesticated deer. This work has resulted in valuable new insights into the aetiology, transmission, pathogenesis, diagnosis, prevention and heritability of resistance to M. bovis infection in ruminants. This knowledge has complemented the existing literature database on bovine and human TB and will provide new strategies for improved diagnosis, vaccination and selective breeding to control TB, which should be relevant for human, domestic livestock and wildlife populations.     

Bovine Mastitis in Selected Areas of Southern Ethiopia

A study on bovine mastitis, designed to determine the causal agents, prevalence of infection and impact of risk factors in three cattle breeds, was conducted in selected areas of southern Ethiopia. A total of 307 lactating and non-lactating cows, of which 162 were indigenous Zebu, 85 Jersey and 60 Holstein-Friesian, were examined by clinical examination and the California mastitis (CMT) test. Of these, 40.4% were positive by CMT and bacteriology for clinical or subclinical mastitis, with prevalence rates of 37.1% and 62.9%, respectively. Out of 1133 quarters examined, 212 (18.7%) were found to be infected, 83 (39.2%) clinically and 129 (60.8%) subclinically. The prevalence of mastitis was significantly higher in Holstein-Friesian than in indigenous Zebu, in non-lactating cows than in lactating cows, in the early lactation stage than in the mid-lactation stage, in cows with lesions and/or tick infestation on skin of udder and/or teats than in cows without this factor, and in the wet season than in the dry season. Mastitis increased with parity number (R = 0.9). Of 248 CMT and clinically positive udder quarter samples analysed microbiologically, 212 were culturally positive for known mastitis pathogens and 36 were negative. Of the 199 positive samples, Staphylococcus accounted for 39.2%, Streptococcus for 23.6%, coliforms for 14.1%, Micrococcus and Bacillus species for 8.0% each and Actinomyces or Arcanobacterium (Corynebacterium) for 7.0%. It was concluded that there was a high prevalence of clinical and subclinical mastitis, mainly caused by Staphylococcus aureus, Streptococcus agalactiae and Escherichia coli, in this study area.     

Risk Factors Associated with the Occurrence of Bovine Tuberculosis in Cattle in the Southern Highlands of Tanzania

A study was conducted in the Southern Highlands of Tanzania to determine the prevalence of bovine tuberculosis and the risk factors associated with the occurrence of the disease in cattle of different categories and in different climatic zones. The overall prevalence of the disease was 13.2%, and 51% of the herds tested contained reactor cattle. Assessment of risk factors was based on comparisons of the reactivity of the cattle in the single comparative intradermal tuberculin test (SCITT). Older cattle were more affected by the disease than yearlings and calves (p<0.0001). There were significant differences between male and female cattle (p<0.05) and between cattle with exotic blood compared to indigenous Short Horn Zebu (SHZ) cattle (p<0.05). The castrated bulls, often used for draught power, were more frequently (p<0.01) affected than the entire bulls, mainly used for breeding. Reactivity to tuberculin did not appear to be influenced by the reproductive status of the animal. The reactivity to tuberculin of pregnant cattle was not significantly different from that of the rest of the cows (p>0.05). However, significantly more (14.6%) lactating cattle reacted in the SCITT than did non-lactating cows (12.0%) (p<0.05). There was a highly significant difference (p<0.001) between reactivity in the SCITT among cattle grazing in the hot and dry lower lands (14.0%) and that in those grazing in the cool and wet highlands (8.7%).     

Seroprevalence Estimation and Risk Factors for <Emphasis Type="Italic">A. marginale</Emphasis> on Smallholder Dairy Farms in Tanzania

A cross-sectional serological survey of A. marginale was conducted on 200 randomly selected smallholder farms in each of the Tanga and Iringa Regions of Tanzania between January and April 1999. Sera, from dairy cattle of all ages, sexes and breeds were tested for antibodies against A. marginale using an indirect enzyme-linked immunosorbent assay. Antibodies to A. marginale were present in cattle throughout the study areas and the overall prevalence was 20% for Tanga and 37% for Iringa. The forces of infection based on the age seroprevalence profile were estimated at 8 for Tanga and 15 for Iringa per 100 cattle years-risk, respectively. In both regions, seroprevalence increased with age (β = 0.01 and 0.017 per year of age, p < 0.005, in Tanga and Iringa, respectively). Older animals in Iringa were significantly and negatively associated with decreased seropositivity (β = −0.002, p = 0.0029). Further results of logistic regression models reveal that geographic location of animals in Tanga was associated with seropositivity (odds ratio (OR) = 2.94, p = 0.005, for Tanga Rural and OR = 2.38, p = 0.066, for Muheza). Animals acquired as a gift in Iringa had higher odds for seropositivity than brought-in cattle (OR = 2.44, p = 0.005). Our study has identified and quantified some key risk factors that can guide planners devising disease control strategies.     

陕西泾阳县奶牛品种改良现状、问题及对策

泾阳县是全国奶牛生产五强县之一,奶畜产业规模稳居西北第一,截至2008年3月,全县奶牛存栏26273头,奶牛单产6015．3kg。但在奶牛品种改良中忽视良种奶牛选种选配,轻视后备母牛培育,后裔测定也很不规范。本文通过对泾阳县奶牛品种改良的调查,全面了解剖析了当地奶牛品种改良工作的现状,指出了奶牛品种改良中存在的主要问题并提出了对策性建议,以实现奶牛养殖的良种化。     

Skin Injuries on the Body and Thigh of Dairy Cows: Associations with Season,Claw Health,Disease Treatment,and other Cow Characteristics

An epidemiological study was conducted in 18 dairy herds with the objective to characterize those groups of cows where skin injuries to the body and thighs occurred most frequently. Data were analyzed with multivariable logistic regression. The epidemiologic patterns were different in first and later lactations. In first lactation some degree of injury occurred among 7.7% of 1793 cows. For most cows occurrence of sole ulcer was positively associated with injury while occurrence of heel horn erosion was negatively associated with injury. The association between injury and body weight differed depending on month of calving (significant interaction). Injuries occurred most frequently among high yielding cows. Severe reproductive, metabolic, and/or infectious diseases were associated with injuries. In later lactations some degree of injury occurred among 13.4% of 832 cows in lactations 2 to 9 where severity of injury increased with lactation number. Injuries occurred least frequently at examinations made in the January to March. They occurred most frequently among cows with sole ulcers. Calving in March through October was associated with injuries especially if the cows were treated for limb disorders. Most cases of injuries occurred early or late in lactation or among high or very low yielding cows in lactations 2 to 9.     

新疆规模化奶牛场牛群结构调查与问题分析

为加快奶牛养殖由数量型向质量效益型转变,促进奶业提质增效高质量发展,助力新疆“十四五”规划开好局、起好步,笔者所在团队对新疆8 个地州、35 个县、85 家规模化奶牛场进行了实地查看走访、数据采集,重点对牛群结构及生产技术参数进行分析。结果发现,大部分奶牛场的牛群结构都存在一些较为突出的共性问题,影响了奶牛场的经营效益与长期发展。本文对问题进行了汇总,并提出了有效的改进措施,旨在引起奶牛场经营者的重视,同时也为日后有针对性地开展技术服务提供参考。     

Antimicrobial Susceptibility Patterns of Clostridium difficile Isolates from Family Dairy Farms

A significant risk factor for developing Clostridium difficile infection (CDI) in humans and animals is associated with the antimicrobial use. It has often been hypothesized that farm animals could be the source for human infection with Clostridium difficile (CD). In the European Union, family‐run dairy farms are the predominant farming model, which are more interlinked within the community compared to large‐scale intensive dairy or beef farms. Therefore, it is important to investigate antimicrobial susceptibility patterns of CD in such environment. A total of 159 CD isolates from 20 family dairy farms were tested with a customized broth microdilution plate for their antimicrobial resistance. Seventeen antimicrobials were selected (amoxicillin, ceftriaxone, clindamycin, daptomycin, erythromycin, fusidic acid, imipenem, levofloxacin, linezolid, metronidazole, moxifloxacin, oxacillin, rifampicin, tetracycline, tigecycline, trimethoprim/sulfamethoxazole and vancomycin), which are commonly used for treatment of CDI in veterinary and human medicine, or were previously applied in CD epidemiological studies. Antimicrobials, which are used for treatment of CDI in humans (metronidazole, vancomycin, fusidic acid, tigecycline, linezolid) inhibited CD growth in vitro. Most CD isolates were resistant to erythromycin (93.1%), daptomycin (69.2%) and clindamycin (46.5%). High multiple‐resistance was found in CD ribotype 012 (n = 5, 100%), some CD SLO 060 (n = 4, 25%) and one CD 033 (n = 1, 1.1%). High multiple‐resistance in this study was linked with CD ribotypes and not with the origin of CD. The low prevalence of these ribotypes (6.3%; 10/159) indicates that family‐run dairy farms are an unlikely source of CD with multiple‐resistance to antimicrobials.     

Classification of worldwide bovine tuberculosis risk factors in cattle: a stratified approach

The worldwide status of bovine tuberculosis (bTB) as a zoonosis remains of great concern. This article reviews the main risk factors for bTB in cattle based on a three-level classification: animal, herd and region/country level. A distinction is also made, whenever possible, between situations in developed and developing countries as the difference of context might have consequences in terms of risk of bTB. Recommendations are suggested to animal health professionals and scientists directly involved in the control and prevention of bTB in cattle. The determination of Millenium Development Goals for bTB is proposed to improve the control/eradication of the disease worldwide.     

Feeding of Dairy Cattle in the Forest-Garden Farms of Kandy,Sri Lanka

A survey on feeding practices was conducted with 60 farmers belonging to four categories (15 farmers in each): male farmers without off-farm income (M^–), male farmers with off-farm income (M⁺), female farmers without off-farm income (W^–), and female farmers with off-farm income (W⁺). Data on herd size, feeds offered, milk production, chest girth, reproduction and management were collected monthly over a period of 1 year. In addition, samples of fodder and concentrates were collected monthly and analysed for dry matter (DM), organic matter (OM), crude protein (CP) and in vitro organic matter digestibility (OMD). Of the 550 rations analysed, grass was included in 99.8% of all rations, followed by gliricidia (65%), creepers (50%) and jak leaves (32%). Consequently, the rations were high in OMD (47–59%) and CP (7.8–23.5%). High-protein forage or coconut cake or both were also included as a supplement in 92% of the rations. Both M^– and W^– farmers had larger (p<0.001) herds (mean 1.8 animal units (AU) per household) than their counterparts with off-farm income (mean 1.44 AU/household), but only the male farmers without off-farm income achieved higher feeding levels (84.4 vs 65.6–72.1 g digestible organic matter (DOM)/kg^0.75 per day) and milk production (6.4 vs 5.3–5.7 L/lactating cow). The lower production of animals kept by female and M⁺ farmers was related to lower feeding levels. M^– farmers realized higher feeding levels than their M⁺ counterparts. W^– farmers did not collect extra feed in response to higher levels of production. It was concluded that dairy farming in the mid-country of Sri Lanka is particularly important for poorer households without income from off-farm employment.     

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.     

Influence of Age and Breed on Natural Bovine Fasciolosis in an Endemic Area (Galicia,NW Spain)

An analysis was undertaken of the effect of breed and age on bovine fasciolosis using antibody and antigen detection ELISAs. A total of 84.3% of the 1284 serum samples examined had positive antibody values and 20.4% exhibited antigenaemia. The seroprevalence of antibodies in crossbred cattle was higher than that in autochthonous Rubia Gallega, Friesian or Brown Swiss cows. The highest percentage antigenaemia occurred in the Brown Swiss cattle, but the breed differences were not statistically significant. Cattle aged 3–5 years had the highest antibody and circulating antigen prevalence and the age differences were significant. It was concluded that the apparent influence of breed was probably closely associated with the husbandry system. The autochthonous Rubia Gallega may be better adapted to fasciolosis as its percentage of antigenaemia was the lowest.     

陕西省某县规模场奶牛结核病阳性率横断面调查

[目的]了解奶牛结核病在陕西省某县的流行情况。[方法]采用横断面研究方法,对该地区存栏量30头以上的规模奶牛场进行测定,估算其个体和群体阳性率,并绘制阳性场空间分布图。目标场是陕西省某县奶牛存栏量≥30头的奶牛场(共20个)。选择两阶段抽样策略:第一阶段,选择所有的20个奶牛场;第二阶段,计算选定奶牛场抽样量并随机选择抽样个体。抽样量采用估计流行率方法,通过Win Episcope 2.0软件计算,设定置信水平(CL)、预期流行率(P)和可接受误差(E)分别为95%、3%和2%。试验方法(PPD皮试)及阳性结果的判定标准参照《动物结核病诊断技术》(GB/T 18645—2002)执行。[结果]该县规模场奶牛结核病个体阳性率为1.7%,群体阳性率为60%。因检测方法特异性偏低,无法得到真实流行率。[结论]通过PPD皮试方法测得陕西省某县规模化奶牛场个体阳性率为1.7%,牛群阳性率为60%。阳性场空间分布相对聚集,均沿公路和河流分布。调查结果提示,在今后的牛结核病检测工作中,应充分考虑到诊断试验的特异性,并持续做好奶牛结核病的监测和净化工作。     

用Wood模型拟合四川地区黑白花奶牛泌乳曲线的研究

用四川省阳坪种牛场 1 992年— 1 997年的黑白花奶牛共计 31 2个泌乳期的泌乳曲线 ,以研究胎次、产犊季节、干奶天数和初产年龄四个因素对模型参数估计值的影响。结果表明 :胎次的差异对参数a、b、c影响显著 ,对参数tmax影响不显著 ;产犊季节的差异对参数tmax影响显著 ,对参数a、b、c影响不显著 ;初产年龄的差异对参数a影响显著 ,对参数b、c、tmax影响不显著 ;干奶天数的差异对参数b、c、tmax影响显著 ,对参数a影响不显著 ;此外还给出了Wood模型拟合四川地区黑白花奶牛泌乳曲线的参数估计值     

Pathology of naturally occurring bovine tuberculosis in England and Wales

The aim of this study was to obtain a contemporary data set of pathology in tuberculin reactor and in-contact cattle in England and Wales. Four hundred animals (200 reactors and 200 in-contacts) from 242 farms located in 14 counties in Western England and Wales were examined. The mean number of lymph nodes (LNs) with tuberculosis (TB)-like lesions per TB-confirmed animal was 1.7 in reactors and 1.5 in in-contact animals. Tuberculous lesions in both reactor and in-contact animals were most commonly observed in the LNs of the thorax, followed by the head and abdomen, particularly the mediastinal, retropharyngeal and tracheobronchial LNs. Twenty-five reactors had macroscopic lesions in the palatine tonsils. Among TB-confirmed cattle, 27% of reactors and 9% of in-contact animals had gross TB-like lesions in the lungs, particularly in the caudal lobes. Gross lesions that were not TB-confirmed were parasitic granulomas (45%), bacterial or mycotic club-forming pyogranulomas (27%) and bacterial abscesses (23%). Diagnostic sensitivity was maximised when bacteriology and histopathology were used concurrently. Stage IV granulomas, alone or in combination with other stages, constituted 63% of lesions, while 16% of lesions were stage I/II granulomas. Caseous necrosis and calcification were common features of the granulomas encountered in natural Mycobacterium bovis infections, even with pathology limited to a small number of sites. Granulomas often covered large areas of histological sections and typically contained only small numbers of acid fast bacilli.     

A Cross-sectional Study of Reproductive Performance of Smallholder Dairy Cows in Coastal Tanzania

A retrospective cross-sectional study was conducted on 200 randomly selected smallholder farms from a mixed dairy farming system in Tanga, Tanzania, between January and April 1999. We estimated the frequency and determinants of long calving interval (LCI), retention of fetal membrane (RFM), dystocia, and abortion in smallholder crossbred cattle and explored birth trends. The mean calving interval was 500 days and birth rate was 65 per 100 cow-years. Dystocia was reported to affect 58% of calvings, and 17.2% of animals suffered RFM. Using mixed effect models, the variables associated with LCI, RFM and dystocia were breed, level of exotic blood and condition score. Zebu breeding was associated with LCI (odds ratio (OR) = 2.3, p = 0.041) and Friesian breeding with lower odds for RF (OR = 0.26, p = 0.020). Animals with higher levels of exotic blood had lower odds for evidence of dystocia (OR = 0.45, p =0.021). Evidence of dystocia was significantly associated with poor condition score (P = −1.10, p = 0.001). Our observations suggest that LCIs are common in smallholder dairy farms in this region and a likely source of economic loss. Dystocia, RFM, poor condition score and mineral deficiency were common problems and were possibly linked to LCI.