Student Case Presentation
Association of milk yield at dry-off with early-lactation clinical mastitis and somatic cell count
| Date/Time: |
8/27/2026 2:30 PM
|
| Presenter: |
Amy Stabell |
| Veterinary School: |
COR |
Abstract:
Cessation of milking at dry-off can lead to increased intra-mammary pressure, milk leakage, and failure of keratin plug formation, increasing the risk of intra-mammary infection. Modern genetics and management have increased cows’ ability to sustain high milk production late into lactation, so our objective was to investigate whether the risk of developing intra-mammary infection after dry-off was higher in cows with sustained high milk production. We assessed the association of daily average milk yield the week prior to dry-off with first test somatic cell linear score and incidence of clinical mastitis within the first 30 days in milk. We collected this data from four commercial free-stall farms in Eastern Wisconsin, milking between 760 and 2,800 cows. Average daily milk yield per cow the week prior to dry-off was 36.6 ± 9.4 kg and ranged from 5.0 kg to 63.6 kg. Median first test linear score was 0.9 (minimum = 0.1, maximum = 9). Out of 1,041 cows, there were 24 cases of clinical mastitis within 30 days in milk. There was no association between milk yield prior to dry-off and odds of mastitis before 30 days in milk (odds ratio = 0.99, 95% confidence interval = 0.98 to 1.0, P = 0.87), but there was an association with first test linear score (R2 = 0.14, P = 0.04). However, this effect appeared to be driven by between-farm differences in milk yield prior to dry-off distribution (P < 0.001). Our results suggest that for farms with similar management styles as our study herds, milk yield prior to dry-off is not associated with development of early lactation clinical mastitis, and farm-specific management factors likely have a greater impact than milk yield prior to dry-off on first test linear score.
