Barkema H W, Schukken Y H, Lam T J, Galligan D T, Beiboer M L, Brand A
Animal Health Service, Drachten, The Netherlands.
J Dairy Sci. 1997 Aug;80(8):1592-9. doi: 10.3168/jds.S0022-0302(97)76089-2.
Interdependency among udder quarters with subclinical mastitis was evaluated on 150 farms using a total of 35,828 udder quarters. The occurrence of high somatic cell count (SCC) (> 250,000 cells/ml) in 0, 3, and 4 quarters occurred at a higher rate than would be expected based on independence of the quarters. For all bacterial species, intramammary infection in 0, 2, 3, or 4 quarters of the same cow occurred at a higher rate than would be expected based on independence of the quarters. Intramammary infection and high SCC were found less often in front quarters than in rear quarters. High SCC and intramammary infection occurred more often in right front quarters than in left front quarters. High SCC in diagonal quarters occurred at a lower rate than expected. Corynebacterium bovis, Streptococcus agalactiae, and Staphylococcus aureus had the highest intraclass correlation within herd. Streptococcus uberis had a very low intraclass correlation within herd. The intraclass correlation within cow for the natural logarithm of SCC was 0.47. Corynebacterium bovis and Strep. agalactiae had the highest intraclass correlation within cow, and Streptococcus dysgalactiae had the lowest. Analytical methods were proposed to manage the problem of interdependence and its effect on the design or evaluation of field studies on subclinical mastitis.
利用总共35828个乳腺区，在150个农场评估了患有亚临床乳腺炎的乳腺区之间的相互依赖性。0个、3个和4个乳腺区出现高体细胞计数（SCC）（>250,000个细胞/毫升）的发生率高于基于乳腺区独立性所预期的发生率。对于所有细菌种类，同一头牛的0个、2个、3个或4个乳腺区发生乳房内感染的发生率高于基于乳腺区独立性所预期的发生率。乳房内感染和高SCC在前乳腺区比在后乳腺区出现得更少。高SCC和乳房内感染在右前乳腺区比在左前乳腺区出现得更频繁。对角乳腺区的高SCC发生率低于预期。牛棒状杆菌、无乳链球菌和金黄色葡萄球菌在牛群中的组内相关系数最高。乳房链球菌在牛群中的组内相关系数非常低。SCC自然对数在奶牛个体内的组内相关系数为0.47。牛棒状杆菌和无乳链球菌在奶牛个体内的组内相关系数最高，而停乳链球菌的组内相关系数最低。提出了分析方法来处理相互依赖性问题及其对亚临床乳腺炎现场研究设计或评估的影响。
