Analysis of udder health in relation to antimicrobial usage in Swiss dairy farms

In Switzerland, standards for milk quality are high. This requires a high level of udder health in dairy cows. Previous studies have shown that mastitis and antibiotic dry cow treatments are the most common causes of antimicrobial consumption in dairy cows. This raises the question of whether a high use of antibiotics is necessary to maintain good udder health. The aim of this study was to analyze the relationship between udder health and antimicrobial usage in Swiss dairy farms. A total of 84 participating farms were evaluated over a period of 18 months. Udder health was assessed using the yield corrected bulk milk somatic cell count from the monthly milk yield data and the number of lactating cows over 150'000 cells/ml per month. Data on antimicrobial consumption were also collected on a monthly basis. In a hierarchical regression model, a significant association between udder health and intramammary antibiotics used during lactation was found. The month of Measurement of the Somatic Cell Count and the veterinarian also had a statistically significant influence on udder health. The consumption of antibiotics for dry cow treatments was not associated with udder health. Antibiotics administered systemically and the production label of the farms was also not statistically associated with udder health in our models. The study was able to show that good udder health is possible with low antimicrobial usage.