Measuring antimicrobial use on dairy farms: A method comparison cohort study

Area of Science:

• Veterinary medicine
• Antimicrobial stewardship
• Agricultural science

Background:

• Accurate measurement of antimicrobial use on UK dairy farms is crucial for surveillance and stewardship.
• Current methods like veterinary sales data, medicine waste bins, and farm records lack validation for quantifying on-farm antimicrobial consumption.
• There is a need to assess the reliability and agreement of these common methods against a validated reference standard.

Purpose of the Study:

• To evaluate the agreement between three common on-farm antimicrobial use measurement methods (veterinary sales data, medicine waste bins, farm records) and a predetermined reference method on UK dairy farms.
• To quantify the reliability and clinical relevance of each method in comparison to the reference standard.

Main Methods:

• A prospective study was conducted on 26 UK dairy farms over 12 months.
• Antimicrobial use was measured using medicine waste bins for discarded packaging.
• Retrospective data from farm medicine records and veterinary sales were collected, with a reference method based on pre- and post-study inventories and veterinary sales data.

Main Results:

• Veterinary sales data demonstrated excellent reliability for injectable and intramammary antimicrobials (CCC > 0.90) and moderate to excellent for others (CCC: 0.68-0.97) compared to the reference method.
• Medicine waste bins showed good to excellent reliability for injectable (CCC: 0.84-0.99) and intramammary products (CCC: 0.78-0.94) but no agreement for other antimicrobial forms.
• Farm medicine records showed no agreement with the reference method for any antimicrobial type.

Conclusions:

• Veterinary sales data serves as a reliable proxy for on-farm antimicrobial use in the UK, especially for injectable antimicrobials, showing good clinical agreement with the reference method.
• Medicine waste bins are a viable alternative for measuring injectable and intramammary antimicrobial use but are less effective for other forms.
• Farm medicine records are not a reliable method for quantifying antimicrobial use on UK dairy farms.
• Accurate quantification of agricultural antimicrobial use is essential for informing animal and human health policies and practices, with implications for national and international surveillance efforts.