Faculty of Veterinary Medicine, University of Calgary, Calgary, AB, Canada T2N 4N1; One Health at UCalgary, University of Calgary, Calgary, AB, Canada T2N 4N1.
Faculty of Veterinary Medicine, University of Calgary, Calgary, AB, Canada T2N 4N1.
J Dairy Sci. 2023 Oct;106(10):7104-7116. doi: 10.3168/jds.2022-23083. Epub 2023 Jul 26.
Infections with antimicrobial resistant pathogens are a major threat to human and animal health worldwide. Further, reduction of livestock-associated antimicrobial use (AMU) is often identified as an area of focus. Selective dry cow therapy (DCT) warrants consideration as an important way to decrease AMU on Canadian dairy farms. In addition, teat sealants (TS) are a nonantimicrobial alternative for prevention of intramammary infection during the dry period. Therefore, objectives of this study were to determine how antimicrobials and TS are used at dry-off on Canadian dairy farms to determine selective DCT uptake and enacted selection protocols. It was expected that these data will provide a baseline understanding of DCT practices and highlight areas for future intervention to further reduce AMU. An observational study was conducted utilizing 2 in-person questionnaires conducted between July 2019 and September 2021 on 144 participating dairy farms in 5 Canadian provinces (British Columbia = 30, Alberta = 30, Ontario = 31, Québec = 29, and Nova Scotia = 24). Overall, 45 farms (31%) reported adopting selective DCT, 95 (66%) enacted blanket DCT, and 4 (3%) did not provide antimicrobial DCT. Farms enacting selective DCT had approximately 50% less intramammary antimicrobials used at dry-off compared with blanket DCT farms. Cow somatic cell count history was the most common criterion for selective DCT decision-making, followed by previous clinical mastitis history, bacteriological culture, and milk production. A slight majority of farms (56%) applied TS to all cows at dry-off, whereas 17 farms (12%) used TS selectively, and 46 farms (32%) did not use TS. Larger herds more often used TS, and farms with an automatic milking system more often used TS selectively than applied to all cows. Results highlighted the variability in antimicrobial treatment and TS use protocols at dry-off on Canadian dairy farms, and the potential for further antimicrobial reduction with increased adoption of selective DCT.
抗微生物耐药病原体感染是全球人类和动物健康的主要威胁。此外，减少与牲畜相关的抗微生物药物使用（AMU）通常被确定为重点关注领域。选择性干奶牛疗法（DCT）是减少加拿大奶牛场 AMU 的重要途径。此外，乳头密封剂（TS）是干奶期预防乳腺炎的非抗生素替代物。因此，本研究的目的是确定在加拿大奶牛场干奶期如何使用抗生素和 TS，以确定选择性 DCT 的采用情况和实施的选择方案。预计这些数据将提供对 DCT 实践的基本了解，并突出未来干预以进一步减少 AMU 的领域。本研究采用观察性研究，于 2019 年 7 月至 2021 年 9 月期间在加拿大 5 个省（不列颠哥伦比亚省=30 个，艾伯塔省=30 个，安大略省=31 个，魁北克省=29 个和新斯科舍省=24 个）的 144 个参与奶牛场进行了 2 次面对面问卷调查。总体而言，45 个（31%）农场报告采用了选择性 DCT，95 个（66%）实施了常规 DCT，4 个（3%）农场没有提供抗生素 DCT。采用选择性 DCT 的农场在干奶期使用的乳房内抗生素约比常规 DCT 农场少 50%。奶牛体细胞计数历史是选择性 DCT 决策的最常见标准，其次是以前的临床乳腺炎病史、细菌培养和产奶量。略多于一半的农场（56%）在干奶期对所有奶牛应用 TS，而 17 个农场（12%）选择性应用 TS，46 个农场（32%）不应用 TS。较大的牛群更常使用 TS，而具有自动挤奶系统的农场更常选择性地使用 TS 而不是应用于所有奶牛。结果突出了加拿大奶牛场干奶期抗生素治疗和 TS 使用方案的多样性，以及随着选择性 DCT 的采用增加，进一步减少抗生素的潜力。
