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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.