Evaluation of certification in the Milk and Dairy Beef Quality Assurance Program and associated factors on the risk of having violative antibiotic residues in milk from dairy farms in Michigan

OBJECTIVE: To determine whether certification in a Milk and Dairy Beef Quality Assurance Program (MDBQAP) was associated with a reduced risk of having antibiotic residues in milk and to define specific management factors that may have predisposed dairy farms to having violative antibiotic residues in milk. SAMPLE POPULATION: 124 dairy farms in Michigan that had > 1 violative residue in milk during 1993 and 248 randomly selected control farms in Michigan that did not have violative residues in milk during 1993. PROCEDURE: A pretested structured questionnaire was mailed to case and control farms. A conditional multivariate logistic regression model was developed to determine risk factors associated with having a violative antibiotic residue in milk. RESULTS: Certification in the MDBQAP did not significantly reduce the risk of having a violative antibiotic residue. Annual treatment of > 10% of a herd for metritis was associated with a reduced risk of having a violative residue. Evidence suggested that a routine request for a milk processor to perform residue testing was associated with a decreased risk of having had a violative antibiotic residue, but routine on-farm residue testing was associated with an increased risk of having had a residue. CONCLUSIONS AND CLINICAL RELEVANCE: MDBQAP certification was associated, although not significantly, with a reduced risk of having violative antibiotic residues in milk. Risk factors significantly associated with violative antibiotic residues are addressed by various critical control points in the MDBQAP and may be indicators for strengths and weaknesses of MDBQAP.