As a part of the study „Health and performance of dairy cows in organic farming from an interdisciplinary point of view – an (intervention-) study on metabolic disorders and mastitis with regard to forage production, feeding management and husbandry practices” quarter milk samples from cows at dry off and after calving were taken by farmers in 101 dairy farms in Germany between January 2008 and April 2010. The objective of this study was to evaluate mastitis prevalence at dry off and at calving and the evaluation of different therapeutic regimes at dry off. 3460 cows from 101 dairy farms were examined. Mastitis prevalence at dry off was comparable to conventional farms. At calving organic farms have high mastitis prevalence due to a low cure rate and a high new infection rate in the dry period. The non-use of dry cow antibiotics or teat sealers result in significantly lower cure rates on quarter level (28.7% vs. 33,2%) and higher new infection rates (29.7% vs. 26.4%). The results show, that dry period is a high-risk period for udder health in organic dairy farms. Improvements of the hygienic conditions, the immune defence and the therapeutic regimes offer high potentials for improvement of udder health
