Dye marked antibiotics for lactating cow mastitis therapy.

Area of Science:

• Veterinary Medicine
• Dairy Science
• Food Safety

Background:

• Antibiotic residue in milk poses a food safety concern for consumers.
• Dairy farmers require effective methods to detect antibiotic contamination in milk.
• Intramammary antibiotic infusions are common treatments for bovine mastitis.

Purpose of the Study:

• To evaluate the efficacy of dye-marked intramammary antibiotic infusions for detecting milk antibiotic residue.
• To determine the milk-out rates of both dye and antibiotic components from treated lactating cows.
• To identify the optimal dye formulation for practical farm application.

Main Methods:

• Six preparations of Albacillin (penicillin and novobiocin) combined with varying concentrations of Food, Drug, and Cosmetic Blue No. 1 or No. 2 were tested.
• Thirty lactating cows received intramammary infusions twice daily for 24 hours.
• Milk samples were collected for 14 post-treatment milkings and analyzed for dye (visual and ion exchange resin methods) and antibiotic residue (cylinder plate and Delvotest-P methods).

Main Results:

• Antibiotic residues were detected up to the sixth milking by Delvotest-P, while the cylinder plate method showed no residues after the fourth milking.
• Visible blue coloration persisted in milk for one to four milkings, depending on dye type and concentration.
• Subvisual dye detection via ion exchange resin lasted for three to five milkings.
• The preparation with 250 mg of Blue No. 1 per infusion demonstrated the most potential, with dye detectable visually for 3-4 milkings and subvisually for 5 milkings.

Conclusions:

• Dye-marked intramammary infusions can serve as a practical visual indicator of antibiotic residue in milk.
• The formulation containing 250 mg of Blue No. 1 per infusion is a promising candidate for dairy farm use.
• Dye persistence generally coincided with or exceeded antibiotic residue persistence, aiding in milk safety management.