Herd characteristics and management practices associated with bulk-tank somatic cell counts in herds in official Dairy Herd Improvement Association programs in Ohio

Objective—To identify herd characteristics and management practices associated with bulk-tank somatic cell counts (BTSCC) in dairy herds in Ohio enrolled in official Dairy Herd Improvement Association (DHIA) programs. Sample Population—186 dairies in Ohio. Procedure—All herds in official DHIA programs in 9 counties were asked to participate. Extensive information regarding herd characteristics and management practices was obtained, using a standardized questionnaire. Bulk-tank milk samples were requested from all participating herds for bacterial culture. Official DHIA test-day records for January 1997 were obtained from all herds enrolled in official DHIA programs in the 9 counties. Potential associations were identified, using multivariable ANOVA. Results—Participation was 186 of 479 (39%) herds. Streptococcus agalactiae and Mycoplasma spp were not isolated from bulk-tank milk samples. Staphylococcus aureus was isolated from 64 of 172 (37%) of the herds. The BTSCC were inversely associated with peak dai...