Evaluation of the Test Characteristics of the HyMast® Bacteriological Test System

Abstract

Mastitis continues to be a disease of major economic importance to the dairy industry, despite the wide use of mastitis control programs. Approaches to mastitis therapy may range from conservative to aggressive, depending on cow and management factors. Knowledge of the organism, prior to treatment, would appear to be of benefit in selecting the most appropriate course of therapy. The HyMast® test (Pharmacia & Upjohn, Kalamazoo, Michigan) is a selective media bacteriological test system for detection of gram-positive (Staphylococci, Streptococci) and gram-negative (coliform) organisms in milk. Although the primary use of this test has been for decision making in mastitis therapy, there is interest in identifying specific organisms from the test. The objectives of this study were to evaluate the sensitivity and specificity of the HyMast test read by producers on-farm and by readers in-clinic at 3 time periods, compared to standard milk bacteriology.