Middleton John R, Hardin David, Steevens Barry, Randle Richard, Tyler Jeff W
Department of Veterinary Medicine and Surgery, College of Veterinary Medicine, University of Missouri, Columbia, MO 65211, USA.
J Am Vet Med Assoc. 2004 Feb 1;224(3):419-23. doi: 10.2460/javma.2004.224.419.
To determine whether somatic cell counts (SCCs) or California mastitis test (CMT) scores for individual quarter milk samples could be used to detect subclinical intramammary infection among dairy cattle in a herd with a high bulk tank SCC.
Prospective clinical trial.
278 Holstein-Friesian dairy cattle from a single herd.
Individual quarter milk samples were collected and submitted for bacterial culture, California mastitis testing, and determination of SCC. Additional milk samples were collected 34 days later and submitted for bacterial culture.
During the initial visit to the herd, milk samples were collected from all 278 cows. However, because of blind mammary quarters or missing data, results for 1,057 quarter milk samples were included. Bacterial culture did not yield any growth for 622 (58.8%) of these samples. Regardless of the cutoff that was used, sensitivity of the CMT score was < or = 0.50 and sensitivity of the SCC linear score (SCS) was < or = 0.60. For 497 mammary quarters, results of bacterial culture of samples collected 34 days apart were concordant; bacterial culture did not yield any growth for 342 (68.8%) of these quarters. Regardless of the cutoff that was used, sensitivity of the CMT score was < or = 0.61 and sensitivity of the SCS was < or = 0.76 for mammary quarters with concordant bacterial culture results.
Results suggest that neither CMT score nor SCC is sensitive enough to be useful as a screening test for identifying infected mammary quarters among dairy cattle in a herd with high bulk tank SCC.
确定个体乳区牛奶样本的体细胞计数（SCCs）或加利福尼亚乳房炎检测（CMT）评分是否可用于检测大容量奶罐SCC较高的牛群中奶牛的亚临床乳房内感染。
前瞻性临床试验。
来自单一牛群的278头荷斯坦-弗里生奶牛。
采集个体乳区牛奶样本并送检进行细菌培养、加利福尼亚乳房炎检测和SCC测定。34天后采集额外的牛奶样本并送检进行细菌培养。
在首次走访该牛群时，从所有278头奶牛采集了牛奶样本。然而，由于存在隐性乳房炎乳区或数据缺失，纳入了1057份乳区牛奶样本的结果。这些样本中622份（58.8%）细菌培养无生长。无论采用何种临界值，CMT评分的敏感性≤0.50，SCC线性评分（SCS）的敏感性≤0.60。对于497个乳房炎乳区，间隔34天采集样本的细菌培养结果一致；这些乳区中342个（68.8%）细菌培养无生长。无论采用何种临界值，对于细菌培养结果一致的乳房炎乳区，CMT评分的敏感性≤0.61，SCS的敏感性≤0.76。
结果表明，对于大容量奶罐SCC较高的牛群，CMT评分和SCC均不够敏感，不足以作为筛查感染乳房炎乳区的检测方法。
