Which antibiotics are detected?

Delvotest is able to detect many of the antiobiotics commonly used in dairy farming to treat diseases, even at levels close to the Maximum Residue Limits (MRL).

For the most widely used antibiotics, the detection threshold of Delvotest is the MRL level.

Rapid tests versus Delvotest
The most common use of antiobiotics on the farm is for intramammary treatment for mastitis, containing antibiotics of the Beta-lactam family. However, in certain countries, such as France, not all treatments contain Beta-lactams. Antibiotic residues not containing Beta-lactams could remain undetected when farmers use "rapid tests", but the residues will be detected with laboratory tests. Farmers using test kits on the farm, should ensure they only use tests that detect a wide range of antibiotics.

Varying contamination risks
A treatment's "contamination power" depends on three elements: the antibiotic concentration in the syringe , the MRL of the antibiotics concerned and the persistence of the antibiotic in the udder.

Dry-off treatments.
Dry-off antibiotic treatments can contaminate hundreds of thousands of litres of milk. When drying-off, each cow is injected with 4 syringes (one per quarter) containing a very high concentration of antibiotics. Milk of a recenlty treated cow are able to contaminate hundreds of thousands of litres of milk.

Antibiotics used in drying-off can remain in the udder for at least for 4 weeks and sometimes up to 10 weeks. Therefore, when calving the milk can contain antibiotic levels superior to the MRL and so return a positive result when tested. The length of time the antibiotics remain in the udder depends on the molecule and the excipient. As a result, in cases of premature calving, it is recommended that the milk is tested before delivery.

Whatever the method of administration, antibiotics can still be found in the milk. The presence of antiobiotics in milk depends on three factors:

Metabolism: the medicine can be changed and broken down within the body
The molecule's ability to pass through the membranes e.g. blood vessels and cell walls
Elimination: urine, faeces, saliva... and milk

Much depends on the specific product formula. Therefore presence in milk varies considerably from one medicine to another for the same antibiotic. In all cases, the concentration decrease curve tends towards zero, but only goes below the detection thresholds several days after the administration. Whatever the treatment methods, there is a real risk of milk contamination. This makes testing imperative!