Subclinical mastitis and associated risk factors on dairy farms in New South Wales

Abstract

Objective: To determine the current prevalence of subclinical mastitis (SCM) and associated risk factors on dairy farms in New South Wales.

Methodology: A survey was sent to 382 dairy farmers to acquire information on the relevant risk factors associated with SCM.

Results: The average herd prevalence of SCM among the 189 respondents (response rate 49.5%) was 29%. Farmers who had herds with a low prevalence (<20% cows with individual somatic cell count (ISCC) >2 × 10⁵ cells/mL) more frequently wore gloves during milking (26% vs 62%), used individual paper towels for udder preparation (16% vs 62%), fed cows directly after milking (47% vs 87%) and more frequently treated cows with high ISCC (69% vs 80%) than farmers who had herds with a high prevalence of SCM (>30% cows with ISCC >2 × 10⁵ cells/mL). The latter more often used selective dry cow therapy (52% vs 24%), compared with low prevalence herds.

Conclusion: The prevalence of SCM in this cross-sectional study is comparable or lower than reported in other studies from North America and the European Union. The outcome provides a benchmark for the current focus of the NSW dairy industry on the management practices associated with a low prevalence of SCM, such as wearing gloves, using paper towels and feeding cows directly after milking.