Different breeds of cattle were observed to have a variable degree of susceptibility to bovine tuberculosis (bTB). The screening of bTB was conducted on 720 dairy cattle consisting of three breeds using the single intradermal cervical comparative tuberculin (SICCT) test. Besides this, 43 SICCT test-positive cattle were used to compare the severity of the pathology of bTB among the three breeds and to identify the causative mycobacteria using spoligotyping. The overall SICCT test positivity was 17.92% (129/720) by pooling all animals in the three farms. There was a significant difference in SICCT test positivity among the three breeds (χ² = 71.06; p < 0.001); the highest (25.34%) was recorded in the crossbreed followed by the Boran breed (10.08%), while the least (3.14%) was recorded in the Jersey breed. On other hand, the highest median pathology score (10.0, interquartile range, IQR = 6.0–17.0) was recorded in Boran followed by cross (5.0, IQR = 3.5–7.5), while the least (3.0, IQR = 2.25–3.0) was recorded in Jersey. Thus, the difference in the median pathology scores was significant [Kruskal Wallis χ(2)2 = 18.78, p < 0.001] among the three breeds. Furthermore, multivariate analysis using ordinal logistic regression by considering age, sex, breed, reproductive status, and location of the farms also showed a significant [χ(2)2 = 11.97, p < 0.01] difference in pathology scores among the three breeds of cattle. Even at a single-herd level at Holeta, the difference in severity of pathology between the Boran and crossbreeds was significant (U = 33.5; p < 0.01). Culture positivity was 39% in 108 suspicious tissues. Fourteen Mycobacterium bovis (M. bovis) and two Mycobacterium tuberculosis (M. tuberculosis) were isolated from the lesions. All the 14 M. bovis isolates belonged to SB0912, while the two M. tuberculosis belonged to SIT54. In conclusion, although the frequency of the SICCT test positivity was high in the crossbreed, a more severe pathology was observed on the Boran (zebu) breed. In addition M. tuberculosis was isolated from TB lesions of dairy cattle, demonstrating the role of M. tuberculosis in causing TB in cattle.

据观察，不同品种的牛对牛结核病 (bTB) 的易感程度不同。使用单次皮内宫颈比较结核菌素（SICCT）试验对由三个品种组成的 720 头奶牛进行了 bTB 筛查。除此之外，还使用 ​​43 头 SICCT 测试呈阳性的牛来比较三个品种之间 bTB 病理的严重程度，并使用 spoligotyping 来识别致病分枝杆菌。通过汇集三个农场的所有动物，总体 SICCT 测试阳性率为 17.92% (129/720)。三个品种之间的 SICCT 测试阳性率存在显着差异（χ ² = 71.06；p < 0.001）；杂交品种中记录最高（25.34%），其次是Boran品种（10.08%），而泽西品种记录最少（3.14%）。另一方面，Boran 记录的中位病理学评分最高（10.0，四分位数范围，IQR = 6.0–17.0），其次是交叉评分（5.0，IQR = 3.5–7.5），而最低（3.0，IQR = 2.25–3.0）是在泽西岛录制的。因此，三个品种的中位病理评分差异显着 [Kruskal Wallis χ(2)2 = 18.78，p < 0.001]。此外，通过考虑年龄、性别、品种、繁殖状况和农场位置，使用序数逻辑回归进行多变量分析也显示三个品种之间病理评分存在显着差异 [χ(2)2 = 11.97, p < 0.01]牛。即使在 Holeta 的单畜群水平上，Boran 品种和杂交品种之间的病理严重程度差异也很显着（U = 33.5；p < 0.01）。 108 个可疑组织的培养阳性率为 39%。从病灶中分离出 14 株牛分枝杆菌 (M. bovis) 和 2 株结核分枝杆菌 (M. tuberculosis)。全部14M。 牛分离株属于SB0912，而两种结核分枝杆菌属于SIT54。总之，虽然杂交品种中 SICCT 测试阳性的频率较高，但在 Boran（瘤牛）品种中观察到更严重的病理。此外，从奶牛的结核病灶中分离出结核分枝杆菌，证明了结核分枝杆菌在引起牛结核病中的作用。