We aimed to identify the dynamics of the within-herd prevalence of Mycoplasma (M.) bovis intramammary infection (IMI) in four dairy herds, estimate prevalence of M. bovis in colostrum and clinical mastitis cases and compare M. bovis strains from calves' respiratory and cow clinical mastitis samples. Within a six-month study period, cow composite milk samples (CMS) were collected three times during routine milk recording, first milking colostrum samples from all calving cows and udder quarter milk samples from clinical mastitis cases. Calf respiratory samples were collected from calves with respiratory disease. Pooled milk samples were analysed for M. bovis with the Mastitis 4B polymerase chain reaction (PCR) test kit (DNA Diagnostic A/S). Prevalence estimates were calculated with Bayesian framework in R statistical programme. cg-MLST was used for M. bovis genotyping. In Herd I and II first testing M. bovis IMI within-herd prevalence (95 % credibility interval (CI)) was 4.7 % (2.9; 6.8) and 3.4 % (2.3; 4.6), changing to 1.0 % (0.1; 1.7) and 0.8 % (0.1; 1.4) in Herd I and 0.4 % (0.0; 0.7) in Herd II at the next samplings. In Herd III and IV first testing M. bovis IMI within-herd prevalence was 12.3 % (9.7; 15.2) and 7.8 % (6.2; 9.5), changing to 4.6 % (3.0; 6.4) and 3.2 % (1.9; 4.8) in Herd III and to 2.8 % (1.9; 3.8) and 4.9 % (3.6; 6.4) in Herd IV at the next samplings. The estimated prevalence of M. bovis in colostrum ranged between 1.7 % (0.2; 2.8) and 4.7 % (2.7; 7.1) and in clinical mastitis cases between 3.7 % (1.7; 6.4) and 11.0 % (7.5; 15.2) in the study herds. M. bovis strains isolated from cows and calves clustered within herds indicating possible transmission of M. bovis between dairy cows and calves. Prevalence of M. bovis in colostrum and clinical mastitis cases as well as the within-herd prevalence of M. bovis IMI was low in endemically infected dairy herds.

中文翻译：

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地方性感染奶牛群中牛支原体乳内感染的畜群内流行情况动态。

我们的目的是确定四种乳牛群中牛支原体（M.）牛乳内感染（IMI）的牛群内流行情况的动态，估算初乳和临床乳腺炎病例中牛分枝杆菌的患病率，并比较犊牛的牛分枝杆菌菌株呼吸道和母牛的临床乳腺炎样本。在六个月的研究期内，在常规牛奶记录过程中，采集了3次奶牛复合奶样品（CMS），所有产犊牛的初乳初乳样品和临床乳腺炎病例的四分之一乳样品。从患有呼吸系统疾病的小牛身上收集小牛呼吸样品。用乳腺炎4B聚合酶链反应（PCR）测试试剂盒（DNA Diagnostic A / S）分析合并的牛奶样品中的牛分枝杆菌。在R统计程序中使用贝叶斯框架计算患病率估计值。cg-MLST用于牛分枝杆菌基因分型。在牛群I和牛群II的首次测试中，牛分枝杆菌IMI的牛群流行率（95％可信区间（CI））为4.7％（2.9; 6.8）和3.4％（2.3; 4.6），更改为1.0％（0.1; 1.7）在下一次采样中，第一组的0.8％（0.1; 1.4）和第二组的0.4％（0.0; 0.7）。在牛群III和牛群IV的首次测试中，牛分枝杆菌IMI的牛群内患病率分别为12.3％（9.7; 15.2）和7.8％（6.2; 9.5），而在2000年中分别变为4.6％（3.0; 6.4）和3.2％（1.9; 4.8）在下一次采样时，III组和IV组分别达到2.8％（1.9; 3.8）和4.9％（3.6; 6.4）。在该研究中，牛初乳分支杆菌的估计患病率在1.7％（0.2; 2.8）和4.7％（2.7; 7.1）之间，在临床乳腺炎病例中在3.7％（1.7; 6.4）和11.0％（7.5; 15.2）之间群。M. 从牛和犊牛中分离出的牛牛分枝杆菌在畜群中聚集，这表明牛分枝杆菌可能在奶牛和牛犊之间传播。在牛初乳和临床乳腺炎病例中，牛分枝杆菌的患病率以及牛分枝杆菌IMI的牛内感染率在地方性感染奶牛群中均较低。