Table 1

Distribution of udder health related parameters in 25 of the organic herds in the study and 1102 conventional herds of the same size and in the same local dairy association. The means and 95% confidence intervals (CI) are derived from multivariable logistic regression analyses and have been corrected for the effects of milk yield, herd size, breed, and lactation number, while ranges are as observed

Organic
 Conventional



Mean
 CI
 Range
 Mean
 CI
 Range
 p-value1
Mastitis treatments, AID2
 9
 6–14
 0–30
 15
 13–16
 0–100
 0.038
Teat injuries, AID
 0.3
 0–2
 0–3
 2
 1–2
 0–42
 0.048
Annual average prevalence of cows in UDS3 0–2
 74
 69–78
 56–98
 64
 62–65
 25–98
 <0.001
Annual average prevalence of cows in UDS 6–9
 10
 8–13
 0–20
 15
 14–15
 0–49
 0.002
Percentage of cows at least once during the year in UDS 6–9
 23
 18–28
 0–50
 32
 31–36
 0–84
 <0.001
Culled due to mastitis
 8
 6–12
 0–28
 8
 7–9
 0–44
 NS

1 Statistical test of difference between organic and conventional herds as estimated in the multivariable logistic regression analyses.

2 Annual incidence density.

3 Udder disease scores (UDS) are graded 0–9, where each figure indicates a 10% increase of the probability that the cow has infectious mastitis

Hamilton et al. Acta Veterinaria Scandinavica 2006 48:11   doi:10.1186/1751-0147-48-11