Abstract：
Mastitis is one of the most common diseases of dairy cattle. It has a high impact on farm economy, farmers\' working time, and antimicrobial usage (AMU). Selective dry cow therapy (SDCT) is an effective means of reducing AMU without negatively affecting udder health. The objective of our study was to evaluate the impact of SDCT implementation on farmer\'s income, working time, and AMU, using a bioeconomic model. A stochastic dairy simulation model (DairyHealthSim) based on a weekly model was used to simulate herd dynamics, reproduction, milk production, culling decisions, health outcomes, and the management of health events. A specific module was developed for the simulation of quarter-level intramammary infection (IMI) acquisition and elimination during the lactation and dry-off periods, and 25 different farm settings were defined to represent herds with various udder health situations. We then defined 20 scenarios of SDCT by combining both the use of different thresholds of somatic cell count and milk bacteriology for treatment allocation and the use of internal teat sealant (ITS). All SDCT protocols had a low impact on farmer\'s income, and we identified some protocols with a positive farm gross margin (up to 15.83 CA$/dried- cow). We also found that adding an ITS to all cows led to greater economic gain. The application of SDCT had a low impact on farmers\' working time, except when milk bacteriology was used for decision-making. Antimicrobial treatment to all cows above 200,000 cells/mL at last control, with the use of ITS on all cows, seems a good choice in most dairy farms. These findings could be used to convince farmers to adopt this strategy at dry-off.
摘要：
乳腺炎是奶牛最常见的疾病之一。它对农业经济有很大的影响，农民的工作时间，和抗菌药物的使用（AMU）。选择性干牛疗法（SDCT）是减少AMU而不会对乳房健康产生负面影响的有效手段。我们研究的目的是评估SDCT实施对农民收入的影响，工作时间,和AMU,使用生物经济模型。采用基于周模型的随机乳制品模拟模型(DairyHealthSim)来模拟牛群动态，繁殖，牛奶生产,剔除决定，健康结果，和卫生事件的管理。开发了一个特定的模块，用于模拟泌乳和干燥期间四分之一级乳房内感染（IMI）的获取和消除，并定义了25种不同的农场环境，以代表具有各种乳房健康状况的牛群。然后，我们通过结合使用体细胞计数和牛奶细菌学的不同阈值进行治疗分配以及使用内部乳头密封剂（ITS）来定义20种SDCT方案。所有SDCT协议对农民收入的影响都很小，我们确定了一些具有正农场毛利率（高达15.83CA$/dried-cow）的协议。我们还发现，向所有奶牛添加ITS可以带来更大的经济效益。SDCT的应用对农民的工作时间影响很小，除非牛奶细菌学用于决策。在最后对照时，对所有超过200,000个细胞/mL的奶牛进行抗菌处理，在所有奶牛上使用ITS，在大多数奶牛场似乎是一个不错的选择。这些发现可以用来说服农民在干旱时采取这一策略。
