Use of Delvotest T for Quantitative Estimation of β-lactam Antibiotic Residues in Waste Milk and for Evaluation of Thermal Treatment Efficiency – a Methodical Pilot Study

The aim of this work was to study possibilities of using microbiological broadspectrum inhibitor test (Delvotest T) for express estimation of antibiotic residues in bovine milk. For quantitative estimation the waste-milk samples were stepwise diluted (dilution array) by antibiotic-free milk until negative test result was achieved. Another objective was to evaluate heat treatment efficiency of waste-milk in order to degrade antibiotic residues in it. Heat treatment (in water bath) at 90°C was chosen according to references in literature. In order to study certain drug residue the waste-milk samples were collected at the next milking after medical treatment. Two different drugs were investigated: Carepen and Norocillin. Preliminary results indicated that the average concentration of antibiotic residue (active substance of drugs) exceeded European MRL (Maximum Residue Limit) 4,100 (± 2,408) and 13.0 (± 5.7) times respectively. The average heat treatment duration at 90°C (until negative test result of Delvotest T) was 15.0 (± 5.0) and 7.8 (± 1.5) hours respectively.