Erskine R J, Eberhart R J, Hutchinson L J, Spencer S B, Campbell M A
Department of Veterinary Science, College of Agriculture, Pennsylvania State University, University Park 16802.
J Am Vet Med Assoc. 1988 Mar 15;192(6):761-5.
Eighteen dairy herds were studied, 12 with a 12-month Dairy Herd Improvement Association herd mean somatic cell count (SCC) less than or equal to 150,000 cells/ml (low SCC) and 6 with a 12-month mean SCC greater than 700,000 cells/ml (high SCC). At the outset of the study, quarter samples for bacteriologic culture were collected (in duplicate) from all quarters of all lactating cows (whole herd culture). Subsequently, quarter milk samples for culture from all cows with clinical mastitis were collected for a period of 6 months. In the herds with low SCC, results of whole herd culture revealed low prevalence of intramammary infection attributable to all major pathogens (less than 4% of all quarters). Prevalence of infection with Streptococcus agalactiae (22.2% of all quarters) and Staphylococcus aureus (6.6% of all quarters) was significantly (P less than 0.05) higher in the herds with high SCC. Mean incidence of clinical mastitis in the herds with low SCC was 4.23 infections/100 cows/month (range, 0.42 to 10.25 infections). In the herds with high SCC, mean incidence was 2.91 infections/100 cows/month (range, 1.33 to 3.92 infections). In the herds with low SCC, infection type, as mean percentage of total clinically infected quarters sampled for culture/herd, was 0.0%, 2.2%, 12.3%, 43.5%, and 28.6% for Str agalactiae, S aureus, streptococci other than Str agalactiae, coliforms, and organisms not isolated, respectively. Respective percentages for the herds with high SCC were 41.5%, 18.3%, 12.6%, 8.0%, and 8.8%. During the study period (from April through January), incidence of clinical mastitis and clinical mastitis caused by coliform bacteria were highest in July and August for herds with low SCC.(ABSTRACT TRUNCATED AT 250 WORDS)
对18个奶牛群进行了研究，其中12个群的12个月奶牛群改良协会牛群平均体细胞计数（SCC）小于或等于150,000个细胞/毫升（低SCC），6个群的12个月平均SCC大于700,000个细胞/毫升（高SCC）。在研究开始时，从所有泌乳奶牛的所有乳区采集用于细菌培养的乳区样本（一式两份）（全群培养）。随后，在6个月的时间里，从所有患有临床型乳腺炎的奶牛采集用于培养的乳区奶样。在低SCC的牛群中，全群培养结果显示，由所有主要病原体引起的乳房内感染患病率较低（占所有乳区的比例不到4%）。无乳链球菌感染患病率（占所有乳区的22.2%）和金黄色葡萄球菌感染患病率（占所有乳区的6.6%）在高SCC的牛群中显著更高（P<0.05）。低SCC牛群中临床型乳腺炎的平均发病率为4.23次感染/100头奶牛/月（范围为0.42至10.25次感染）。在高SCC的牛群中，平均发病率为2.91次感染/100头奶牛/月（范围为1.33至3.92次感染）。在低SCC的牛群中，作为培养采样的临床感染乳区总数的平均百分比，无乳链球菌、金黄色葡萄球菌、非无乳链球菌的链球菌、大肠埃希菌和未分离出的微生物的感染类型分别为0.0%、2.2%、12.3%、43.5%和28.6%。高SCC牛群的相应百分比分别为41.5%、18.3%、12.6%、8.0%和8.8%。在研究期间（从4月到1月），低SCC牛群的临床型乳腺炎发病率以及由大肠埃希菌引起的临床型乳腺炎发病率在7月和8月最高。（摘要截短于250字）
