Department of Population Health Sciences, Utrecht University, Utrecht 3584 CL, the Netherlands.
Department of Population Health Sciences, Utrecht University, Utrecht 3584 CL, the Netherlands; GD Animal Health, 7400 AA Deventer, the Netherlands.
J Dairy Sci. 2020 Aug;103(8):7302-7314. doi: 10.3168/jds.2019-17960. Epub 2020 May 29.
Mastitis is one of the major causes for antimicrobial use on dairy cattle farms. On farms with an automatic milking system (AMS), diagnostics differ from those with a conventional milking system (CMS), with potentially a different attitude toward mastitis treatment. This may result in differences in antimicrobial usage (AMU) between these 2 types of farms. The aims of this study were (1) to compare AMU between AMS and CMS farms, (2) to identify variables associated with AMU in both types of herds, and (3) to describe the distribution of mastitis-causing pathogens and their antimicrobial resistance patterns. Data on AMU was collected for 42 AMS and 254 CMS farms in the Netherlands and was expressed as animal-defined daily dose (ADDD). The ADDD variables were total usage (ADDD), intramammary usage during lactation (ADDD), usage for dry cow therapy (ADDD), and usage by injection (ADDD). Eighteen AMS farms and 24 CMS farms participated in a survey on factors potentially related to AMU. These farmers collected 5 quarter milk samples from quarters with clinical mastitis or high somatic cell count, which were subjected to bacteriological culture and antimicrobial susceptibility testing. In addition, routinely collected udder health data of these farms were used in the analysis. Nonlinear principal component analysis (NLPCA) was used to explore associations between AMU, udder health, and questionnaire variables. The ADDD and ADDD were comparable between AMS and CMS farms, whereas ADDD tended to be lower and ADDD higher on AMS farms than on CMS farms. The NLPCA yielded 3 principal components (PC) that explained 48% of the variation in all these variables. The AMS farms were not distinguished from CMS farms in the principal component space. The 3 PC represented different aspects of udder health, ADDD, and treatment strategy. Differences in treatment strategy were unrelated to total antimicrobial usage or overall udder health. The distribution of mastitis-causing pathogens and their antimicrobial resistance were comparable between AMS and CMS farms. In conclusion, our study shows that AMU on AMS farms was similar to that of CMS farms, but AMS farmers tend to apply more injectable and fewer intramammary treatments during lactation than CMS farmers. Across both farm types, farmers' attitudes toward udder health in general and toward mastitis treatment are associated with AMU.
乳腺炎是奶牛场使用抗生素的主要原因之一。在使用自动挤奶系统 (AMS) 的农场，诊断方法与使用传统挤奶系统 (CMS) 的农场不同，因此对乳腺炎治疗的态度可能也不同。这可能导致这两种类型的农场之间使用抗生素的差异。本研究的目的是：（1）比较 AMS 和 CMS 农场之间的抗生素使用情况；（2）确定两种类型牛群中与抗生素使用相关的变量；（3）描述乳腺炎病原体的分布及其抗生素耐药模式。在荷兰，共收集了 42 个 AMS 农场和 254 个 CMS 农场的抗生素使用数据，并以动物定义的每日剂量（ADDD）表示。ADDD 变量包括总用量（ADDD）、泌乳期内的乳腺内用量（ADDD）、干奶牛治疗用量（ADDD）和注射用量（ADDD）。18 个 AMS 农场和 24 个 CMS 农场参与了一项与抗生素使用相关的潜在因素调查。这些农民从患有临床乳腺炎或高体细胞计数的乳房中采集了 5 个 quarters 牛奶样本，这些样本进行了细菌培养和抗菌药物敏感性测试。此外，还使用了这些农场常规收集的乳房健康数据进行分析。采用非线性主成分分析（NLPCA）探索了抗生素使用、乳房健康和问卷调查变量之间的关系。AMS 和 CMS 农场的 ADDD 和 ADDD 相当，而 AMS 农场的 ADDD 倾向于低于 CMS 农场，ADDD 则倾向于高于 CMS 农场。NLPCA 产生了 3 个主成分（PC），解释了所有这些变量 48%的变化。在主成分空间中，AMS 农场与 CMS 农场无法区分。这 3 个 PC 代表了乳房健康、ADDD 和治疗策略的不同方面。治疗策略的差异与总抗生素使用量或整体乳房健康无关。AMS 和 CMS 农场引起乳腺炎的病原体及其抗生素耐药性的分布相似。总之，本研究表明，AMS 农场的抗生素使用量与 CMS 农场相似，但 AMS 农场的农民在泌乳期倾向于使用更多的注射用抗生素和更少的乳腺内抗生素治疗。在这两种类型的农场中，农民对乳房健康的总体态度和对乳腺炎治疗的态度与抗生素使用量相关。
