Haapala Vera, Vähänikkilä Nella, Kulkas Laura, Tuunainen Erja, Pohjanvirta Tarja, Autio Tiina, Pelkonen Sinikka, Soveri Timo, Simojoki Heli
Department of Production Animal Medicine, Faculty of Veterinary Medicine, University of Helsinki, Paroninkuja 20, 04920 Saarentaus, Finland.
Finnish Food Authority, Neulaniementie 4, 70210 Kuopio, Finland.
J Dairy Sci. 2021 Feb;104(2):2254-2265. doi: 10.3168/jds.2020-18814. Epub 2020 Dec 11.
As Mycoplasma bovis spreads to new countries and becomes increasingly recognized as a disease with major welfare and economic effects, control measures on dairy farms are needed. To minimize the risk of infection spread to naive herds, all possible risk factors for M. bovis infection should be identified and controlled. Mycoplasma bovis was first diagnosed in dairy cattle in Finland in 2012, and by January 2020, 86 Finnish dairy farms (<1.5%) supporting M. bovis infections were identified. We evaluated risk factors for M. bovis infection using a questionnaire provided to 40 infected and 30 control dairy farms. Control measures were advised for 19 of the infected dairy farms during visits by a veterinarian. The course of the infection on those farms was followed by analyzing calf nasal swabs with PCR for presence of M. bovis 4 times at 6-mo intervals. Control measures included culling of M. bovis mastitic cows, isolation of new calves from older animals after initial M. bovis mastitic cows had been culled, prevention of nose-to-nose contact with infected animals, early detection of mastitis cases using M. bovis PCR, and hygiene measures mainly related to milking, calf pens, feeding buckets, and teats. Farms implemented the control measures related to the isolation of calves or avoidance of nose-to-nose contact in various ways, according to farm structures and financial circumstances. In our study, the control measures recommended to the dairy farms appeared effective, such that 13 of 19 farms reached a low risk level during at least 3 consecutive negative samplings from calves, with no M. bovis mastitis detected subsequently. Among risk factors, insemination with an M. bovis-positive bull indicated a trend of increasing the odds of M. bovis infection on the farm in a multivariable logistic model. In contrast, higher herd average milk yield had an association with lower odds for M. bovis infection. Occurrence of other infectious diseases affecting several animals on the dairy farm in the previous 6 mo before M. bovis infection were more frequent on M. bovis-infected farms.
随着牛支原体传播到新的国家，并越来越被认为是一种对动物福利和经济有重大影响的疾病，奶牛场需要采取控制措施。为了将感染传播到未感染牛群的风险降至最低，应识别并控制所有可能导致牛支原体感染的风险因素。牛支原体于2012年在芬兰首次在奶牛中被诊断出来，到2020年1月，已确定有86个芬兰奶牛场（<1.5%）存在牛支原体感染。我们通过向40个感染牛支原体的奶牛场和30个对照奶牛场发放问卷，评估了牛支原体感染的风险因素。在兽医出诊期间，为19个感染奶牛场提供了控制措施建议。通过每隔6个月用PCR分析犊牛鼻拭子中牛支原体的存在情况，对这些农场的感染过程进行跟踪。控制措施包括淘汰感染牛支原体的患乳房炎奶牛，在最初感染牛支原体的患乳房炎奶牛被淘汰后，将新出生的犊牛与成年动物隔离，防止与感染动物鼻对鼻接触，使用牛支原体PCR早期检测乳房炎病例，以及主要与挤奶、犊牛栏、喂料桶和乳头相关的卫生措施。各农场根据农场结构和财务状况，以各种方式实施了与犊牛隔离或避免鼻对鼻接触相关的控制措施。
在我们的研究中，向奶牛场推荐的控制措施似乎是有效的，以至于19个农场中有13个在犊牛至少连续3次阴性采样期间达到了低风险水平，随后未检测到牛支原体乳房炎。在风险因素中，用感染牛支原体的公牛进行人工授精在多变量逻辑模型中显示出增加农场感染牛支原体几率的趋势。相比之下，牛群平均产奶量越高，感染牛支原体的几率越低。在感染牛支原体之前的6个月内，奶牛场中影响多只动物的其他传染病在感染牛支原体的农场中更频繁发生。
