ICBAS, Department of Veterinary Clinics, Instituto de Ciências Biomédicas Abel Salazar, University of Porto, R. Padre Armando Quintas, 7, 4485-661 Vairão, Vila do Conde, Portugal.
Prev Vet Med. 2013 Jan 1;108(1):21-7. doi: 10.1016/j.prevetmed.2012.07.001. Epub 2012 Jul 24.
The objective of this study was to evaluate the effect of some management practices on the prevalence of Mycoplasma spp. in Northwestern Portuguese dairy farms from bulk tank milk (BTM) samples. Additionally, the within-herd prevalence of Mycoplasma spp. was also determined, but only in BTM positive herds. From May 2007 to November 2008, 492 BTM samples from 164 dairies randomly chosen in a population of 1234 dairy farms were analyzed. Five herds (3.0%) had positive mycoplasmal culture results, from which 4 out of 164 (2.4%) were Mycoplasma bovis, with simultaneous presence of Mycoplasma bovigenitalium or Mycoplasma canadense in two of those samples. In one out of 164 (0.6%) herds Mycoplasma capricolum subsp. capricolum was also found. In BTM positive Mycoplasma spp. herds, the apparent intra-herd prevalence was low and varied between 2.5% and 4.5%. Multiple locus variable-number of tandem-repeat analysis was conducted in order to compare the genetic relationship between the isolates. Mycoplasma spp. was found to be present in cows with subclinical mastitis with or without California Mastitis Test positive results, hence all cows should be tested when the agent is isolated from bulk tank rather than selecting suspected cows. A multivariable logistic regression using the Firth's penalized maximum likelihood estimation was performed showing that increasing number of lactating cows (OR=1.05; P<0.01) was associated with a higher probability of isolating Mycoplasma spp. On the other hand, identifying problem cows was associated with a lower probability (OR=0.06; P<0.05). Particular importance was given to the prevalence of M. bovis, and the results obtained highlight the need to include this agent in mastitis control protocols in national dairies and in sanitary controls of transitioned animals between European countries.
本研究旨在评估一些管理措施对葡萄牙西北部奶牛场牛奶样品中支原体流行的影响。此外，还确定了牛奶样品阳性牛场的牛场内支原体流行情况，但仅针对牛奶样品阳性牛场。2007 年 5 月至 2008 年 11 月，对随机选择的 1234 个奶牛场中的 164 个奶牛场的 492 个牛奶样品进行了分析。5 个牛场（3.0%）的支原体培养结果为阳性，其中 4 个（2.4%）为牛支原体，2 个同时存在牛生殖道支原体或加拿大支原体。在 164 个牛场中的 1 个（0.6%）中还发现了羊支原体山羊亚种。在牛奶样品阳性的支原体牛场中，牛场内的显性流行率较低，为 2.5%至 4.5%。为了比较分离株的遗传关系，进行了多位点可变数量串联重复分析。发现支原体存在于患有临床型或隐性乳腺炎的奶牛中，无论加利福尼亚乳房炎试验结果是否阳性，因此当从牛奶罐中分离出该病原体时，所有奶牛都应进行检测，而不是选择疑似奶牛。采用 Firth 惩罚最大似然估计的多变量逻辑回归分析表明，泌乳牛数量的增加（OR=1.05；P<0.01）与分离支原体的概率增加相关。另一方面，确定问题牛与较低的分离概率相关（OR=0.06；P<0.05）。特别重视牛支原体的流行情况，结果强调需要在国家奶牛场的乳腺炎控制方案和欧洲国家之间过渡动物的卫生控制中纳入该病原体。
