Abstract：
Selective treatment of clinical mastitis (STCM) potentially reduces antimicrobial use without negative implications on cow\'s milk production or health. However, this approach comes with additional costs. The aim of this study was to evaluate the net cash impact (NCI) of implementing STCM compared with blanket treatment of clinical mastitis (BTCM) under different diagnostic-test turnaround times (24 h, 14 h, and 8 h) using a stochastic partial budget analysis with Monte Carlo simulation. The target population was European commercial dairy herds; therefore, the model inputs were primarily from European sources. Additionally, variables associated with dairy management programs were obtained from USDA sources, worldwide multisite clinical trials, and expert opinion. The output was calculated by subtracting the cost of STCM from the cost of BTCM and it represented the expected NCI if a herd switched from BTCM to STCM. Depending on the time-to-treatment efficiency and diagnostic-test turnaround time, the expected mean NCI, assuming that STCM has no impact on the cow\'s future health or production, ranged from +€8.7 to +€12.4 per case with 72.4% to 84.8% of the iterations being ≥ €0. Moreover, using the numerically favorable health and production effects of STCM reported in the literature, the expected mean NCI ranged from +€44.5 to +€48.1 per case with 93.6% to 95.4% of the iterations being ≥ €0. The variables with the greatest contribution to NCI variance were proportion of gram-positive cases (39.2% of the variance) and days out of the tank for treated cows (22.0%). However, if future cow\'s health and production were accounted for, culling risk (24.6%), recurrence risk (19.4%), and milk yield (10.6%) would have the greatest contribution to NCI. The sensitivity analysis indicated that farms with high clinical mastitis incidence, low proportion of gram-positive cases, large number of days out of the tank for treated cows, higher milking frequency or using automatic milking systems, not using the highest priced diagnostic tests, and having high antimicrobial treatment costs are the best candidates for STCM. Improving time-to-treatment efficiency, for example, by using a rapid diagnostic test, leads to a favorable NCI, while high daily milk yield and milk price enhances the NCI in already positive scenarios. Finally, the cash flow entirely depends on future cow\'s health and milk yield. In conclusion, results indicate that overall, STCM is a practice that positively impacts the NCI of many herds.
摘要：
临床乳腺炎（STCM）的选择性治疗可能会减少抗菌药物的使用，而不会对奶牛的牛奶产量或健康产生负面影响。然而,这种方法伴随着额外的成本。本研究的目的是评估在不同诊断测试周转时间（24h，14h,和8h)使用蒙特卡罗模拟的随机部分预算分析。目标人群是欧洲商业奶牛群；因此，模型输入主要来自欧洲来源。此外,与乳制品管理计划相关的变量来自美国农业部的来源，全球多站点临床试验，和专家意见。通过从BTCM的成本中减去STCM的成本来计算输出，并且如果牛群从BTCM切换到STCM，则表示预期的NCI。根据治疗时间效率和诊断测试周转时间，预期平均NCI，假设STCM对奶牛未来的健康或产量没有影响，每例+8.7欧元至+12.4欧元，72.4%至84.8%的迭代≥0欧元。此外，利用文献中报道的STCM在数值上有利的健康和生产效应，预期平均NCI为每例+€44.5至+€48.1,其中93.6%至95.4%的迭代≥€0.对NCI方差贡献最大的变量是革兰氏阳性病例的比例（方差的39.2％）和处理母牛的出罐天数（22.0％）。然而,如果考虑到未来奶牛的健康和产量，剔除风险(24.6%)，复发风险（19.4%），牛奶产量(10.6%)对NCI的贡献最大。敏感性分析表明，临床乳腺炎发病率高的农场，革兰阳性病例比例低，处理过的奶牛离开水箱的天数很多，更高的挤奶频率或使用自动挤奶系统，不使用价格最高的诊断测试，具有较高的抗菌治疗成本是STCM的最佳选择。提高治疗时间效率，例如,通过使用快速诊断测试，导致有利的NCI，而高的日产奶量和牛奶价格在已经积极的情况下提高了NCI。最后,现金流完全取决于未来奶牛的健康和产奶量。总之,结果表明，总体而言，STCM是一种对许多牛群的NCI产生积极影响的做法。
