title: Subclinical mastitis in dairy cows in Swiss organic and conventional production systems.
abstract: The objective was to compare the prevalence of subclinical mastitis (SM) and of udder pathogens in 60 Swiss organic (OP) and 60 conventional production systems (CP). Cows (n=970) were studied for SM prevalence and udder pathogens at median 31 d and 102 d post partum. Cows showing a >or=1+ positive California Mastitis Test (CMT) in at least one quarter were considered to have SM. Cow-level prevalences of SM for visits at 31 d and 102 d post partum (39% and 40% in OP and 34% and 35% in CP) were similar, but quarter-level prevalences of SM were higher (P<0.02) in OP than CP (15% and 18% in OP and 12% and 15% in CP). Median somatic cell counts in milk at 31 d post partum were higher (P<0.05) in OP than CP cows (43000 and 28000 cells/ml, respectively), but were similar at 102 d post partum in OP and CP cows (45000 and 38000 cells/ml, respectively). In milk samples from quarters showing a CMT reaction >or=2+ the prevalences of coagulase negative staphylococci were lower (P<0.05) at 102 d post partum, whereas prevalences of non-agalactiae streptococci were higher (P<0.05) in OP than in CP cows at 31 d and 102 d post partum. In conclusion, under Swiss conditions, subclinical mastitis is a greater problem in organic than in conventional production systems, but differences are not marked.
authors.affiliation: Division of Nutrition and Physiology, Institute of Animal Genetics, Nutrition and Housing, Vetsuisse Faculty, University of Bern, CH-3012 Bern, Switzerland.
authors.forename: Markus
authors.initials: M
authors.lastname: Roesch
authors.forename: Marcus
authors.initials: M
authors.lastname: G Doherr
authors.forename: Walter
authors.initials: W
authors.lastname: Schären
authors.forename: Melchior
authors.initials: M
authors.lastname: Schällibaum
authors.forename: Jürg W
authors.initials: JW
authors.lastname: Blum
mesh_terms: D000818:Animals; D002417:Cattle; D002452:Cell Count / Q000662:veterinary; D003612:Dairying / Q000379:methods*; D005260:Female; D008414:Mastitis, Bovine / Q000175:diagnosis* / Q000453:epidemiology*; D008892:Milk / Q000166:cytology / Q000382:microbiology; D015995:Prevalence; D013557:Switzerland / Q000453:epidemiology