Avoiding Drug Residues

Adapted by Betsy Karle – UCCE Northern Sacramento Valley

While cull cows and bull calves aren’t the primary source of income on dairies, they are a significant source of drug residue violations, and have regulatory agencies looking for solutions. A recently accessed “repeat residue violator information system report” was dominated by bob-veal and dairy cow residues including neomycin, penicillin, flunixin, sulfadimethoxine, tulathromycin, and desfuroylceftiofur. Here are some points to help your dairy stay off the residue list.

Any deviation in labeled dose, route, rate, duration, or indication of any drug constitutes extra-label drug use (ELDU) and must be specifically recommended by your herd veterinarian. There is certainly a place for ELDU, but it’s important to note that labeled withdrawal times no longer apply whenever these changes are made. Penicillin is a classic example- the bottle label hasn’t been changed for years, but veterinarians routinely prescribe a different dose to increase effectiveness. Be sure you have a label from your vet with the appropriate information, especially the re-calculated withdrawal time. Re-visit your employee training programs to ensure that individuals responsible for medicating animals are comfortable giving injections via all routes- subcutaneous, intramuscular, and intravenous. For example, an injection of the pain-reliever flunixin given in the muscle or under the skin instead of IV, as indicated in the label, will increase the withdrawal time by weeks.

Calves sold at a day or two old are another significant source of drug residues. If these calves are fed colostrum with dry-treatment antibiotic residue or medicated milk replacer, they may end up with a tissue residue if harvested before the withdrawal time has passed. Be sure your calf buyer knows if your bull calves have been fed anything that needs to clear their system before harvest.

Don’t forget that things change. For example, the residue test for dexamethasone, which is violative at any level, has become much more sensitive, lowering the detectable concentration.  The extra label use of cephalosporins has been restricted, making any ELDU outside of a veterinary prescription a violation. Labels also change- Excenel^® RTU EZ, for example, is a newer formulation that now has a 4 day slaughter withdrawal. Records and protocols need to be updated when these changes occur.

As with so many other details, good records are vital. Shipping a cow a day before her withdrawal time has passed is not worth the risk and can be avoided with good records. Emphasize the importance of recording all treatments to avoid any miscommunication and be clear about the significance of cull cows to the food supply.

Additional, detailed resources and training materials in English and Spanish are available at the following websites:

http://dairybeef.ucdavis.edu/home.htm

http://www.nationaldairyfarm.com/manual-form-library-comprehensive

To simplify information, trade names of products have been used.  No endorsement of named products is intended, nor is criticism implied of similar products which are not mentioned.

Link to PDF Version: Avoiding Drug Residues