Patterns of bovine dairy submissions to the California Veterinary Diagnostic Laboratory System

Department of Epidemiology and Preventive Medicine, School of Veterinary Medicine, University of California, Davis 95616.

Dairy cattle submissions to the California Veterinary Diagnostic Laboratory System (CVDLS) were analyzed to determine submitter statistics. Eligible submissions were those received July 1, 1987 through December 31, 1989 for reasons other than regulatory brucellosis serology. A comprehensive list frame of California dairies was constructed from Brucella Ring Test information and served as the comparison population for the study. Analyses were performed based on geographic location, herd size, proximity to a CVDLS laboratory, and frequency of submission. Thirty-nine percent of the 2,490 California dairies in the reference population had submitted specimens greater than or equal to 1 time to the CVDLS during the study period. Twenty-three percent of the reference population had submitted greater than or equal to 2 times. Specimens were more likely to be submitted from larger herds than smaller herds. Larger dairies also submitted specimens more frequently. Dairies in the northern part of the state were more likely to submit specimens and submitted more frequently than southern herds when herd size was accounted for in the analysis. Mean submission rate (+/- SD) for the 970 submitting dairies was 1.4 (+/- 1.8) submissions/year. Forty-six percent of the dairies accounted for 80% of submissions, whereas only 14% of dairies accounted for 50% of all diagnostic dairy submissions.