Oliveira L, Hulland C, Ruegg P L
Department of Dairy Science, University of Wisconsin, Madison 53706.
J Dairy Sci. 2013;96(12):7538-49. doi: 10.3168/jds.2012-6078. Epub 2013 Oct 11.
In recent years, the US dairy industry has experienced significant demographic changes, with an increase in the number of large herds. The objectives of the present study were to characterize clinical mastitis occurring in cows on large dairy herds in Wisconsin. Participating herds (n=50) were required to have a minimum of 200 lactating animals, participate in monthly DHI testing (including monthly individual cow somatic cell count), use computerized herd records, use a milking routine that included fore-stripping quarters for detection of mastitis, and use antimicrobials to treat affected cows. After study personnel visited the farm, each herd was instructed to enroll the next 17 cows that experienced clinical mastitis, regardless of severity. At detection of clinical mastitis and 14 to 21 d after treatment ended, duplicate quarter milk samples were collected from all affected quarters and used for microbiological analysis. Treatments of affected cows were performed according to existing individual farm protocols. Cow level follow-up data was collected for 90 d after enrollment. Microbiological diagnoses at enrollment included gram-negative (35.6%), no growth (27.3%), gram-positive (27.5%), and other (9.6%). Of the 741 cases, the most prevalent pathogens were Escherichia coli (22.5%), followed by environmental streptococci (12.8%), Klebsiella spp. (6.9%), and coagulase-negative staphylococci (6.1%). Bacteriological cure was 75.0% for cases caused by gram-negative pathogens (n=136), 50.8% for cases caused by gram-positive pathogens (n=128), 47.5% for cases caused by other pathogens (n=40), and 73.2% for cases which did not result in microbial growth (n=123). Of the 583 cases with severity recorded, the distribution of mild, moderate, and severe symptoms was 47.8, 36.9, and 15.3%, respectively. The majority of cases presenting with severe symptoms were caused by gram-negative pathogens. Treatment cure was greater for gram-negative pathogens and cases for which no pathogens were recovered as compared with cases caused by other etiologies. Cows experiencing severe cases were more likely to receive multiple antimicrobial treatments.
近年来，美国乳制品行业经历了显著的人口结构变化，大型牛群数量增加。本研究的目的是描述威斯康星州大型奶牛场奶牛发生的临床乳腺炎特征。参与研究的牛群（n = 50）需至少有200头泌乳动物，参与每月的奶牛性能测定（DHI）测试（包括每月个体奶牛体细胞计数），使用计算机化的牛群记录，采用包括挤奶前先挤出部分乳汁以检测乳腺炎的挤奶程序，并使用抗菌药物治疗患病奶牛。研究人员访问农场后，指示每个牛群纳入接下来17头发生临床乳腺炎的奶牛，无论病情严重程度如何。在检测到临床乳腺炎时以及治疗结束后14至21天，从所有患病乳腺采集双份乳汁样本用于微生物分析。患病奶牛的治疗按照各农场现有的方案进行。在纳入研究后90天收集奶牛个体的随访数据。纳入研究时的微生物诊断包括革兰氏阴性菌（35.6%）、无生长（27.3%）、革兰氏阳性菌（27.5%）和其他（9.6%）。在741例病例中，最常见的病原体是大肠杆菌（22.5%），其次是环境链球菌（12.8%）、克雷伯菌属（6.9%）和凝固酶阴性葡萄球菌（6.1%）。由革兰氏阴性病原体引起的病例（n = 136）细菌学治愈率为75.0%，由革兰氏阳性病原体引起的病例（n = 128）为50.8%，由其他病原体引起的病例（n = 40）为47.5%，未检测到微生物生长的病例（n = 123）为73.2%。在记录了严重程度的583例病例中，轻度、中度和重度症状分布分别为47.8%、36.9%和15.3%。出现严重症状的大多数病例由革兰氏阴性病原体引起。与其他病因引起的病例相比，革兰氏阴性病原体和未检测到病原体的病例治疗治愈率更高。经历严重病例的奶牛更有可能接受多种抗菌治疗。
