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Table 3 Final multivariable negative binomial regression model between management practices and clinical mastitis (incidence rate ratios (IRR) and 95% confidence intervals (CI)) from 204 Swiss dairy farms with a free-stall and >10 cows in 2010

From: Questionnaire-based study to assess the association between management practices and mastitis within tie-stall and free-stall dairy housing systems in Switzerland

Factor Category IRR (95% CI) P-value
Milk yield High (> 6,122 kg) 1.25 (1.03-1.52) 0.01
Low (≤ 6,122 kg) 1.0 -
Somatic cell count controls At longer intervals 1.44 (1.13-1.84) 0.003
≤2 times/month 1.0 -
Bacteriological test carried out for clinical mastitis Never 0.61 (0.42-0.88) 0.01
Always/occasionally 1.0 -
Dry cow udder controls during the dry period Yes 0.67 (0.54-0.83) <0.001
No 1.0 -
Teat cleaning material Washable towel 1.53 (1.04-2.25) 0.02
Other† 1.0 -
Body condition scoring No 0.74 (0.62-0.90) 0.002
Yes 1.0 -
Important characteristic when selecting a bull for artificial insemination Total merit values 1.57 (1.17-2.11) 0.002
Other‡ 1.0 -
Clean bedding material at calving Yes 1.72 (1.24-2.38) 0.001
No 1.0 -
Hands and arms are cleaned if intervention is required at calving Yes 0.75 (0.61-0.93) 0.009
No 1.0 -
Ropes or chains available at calving if required Yes 1.37 (1.08-1.75) 0.009
No 1.0 -
  1. Paper towel, wood wool, wet towels with disinfectant, wet towels without disinfectant, no material.
  2. Milk yield, fat and protein content of milk, somatic cell count in milk, exterior, ease of calving, length of productive life, milking speed/persistence of lactation, fertility of the dam, beef production.