The good news: The total rate of violation was 0.7%, meaning 99.3% of milk samples were free of residues. FDA sampled milk from nearly 2,000 dairy farms, and found drug residues that exceeded tolerance or safe levels on just 15 farms. One farm tested positive for two drugs.
The bad news: All of the residues came from drugs that are not approved for use in lactating dairy cows. And one of them, Ciprofloxacin, is prohibited from use in any food animal. (Note: Ciprofloxacin is the metabolite of Enrofloxacin (Baytril), which is approved for specific bacterial respiratory tract pathogens in some classes of cattle, but is prohibited from use in lactating dairy cattle.)
Another, Sulfamethazine, is prohibited in lactating dairy cattle and cannot even be used in an extra-label manner, says John Middleton, Professor of Food and Animal Medicine and Surgery with the University of Missouri’s College of Veterinary Medicine. In addition, there are no injectable forms of Gentamicin approved for use in dairy cattle, he says.
“Florfenicol (Nuflor/Resflor), Tilmicosin (Micotil), and Tulathromycin (Draxxin) are all used for treatment of bovine respiratory disease caused by certain bacterial pathogens in beef cattle and can be used in younger dairy stock, but none have a label for lactating dairy cattle,” Middleton adds.
Florfenicol, Tilmicosin and Tulathromycin could be used in an extra-label manner with a veterinarian’s prescription. But the veterinarian would have to justify why a labeled drug for use in adult dairy cattle would not work and prescribe a sufficiently extended milk and meat withhold, says Middleton.
Ceftiofur (Excenel, Excede, Naxcel), Ampicillin (Polyflex), Sulfadimethoxine (Albon) and Oxytetracycline (LA-200) are all examples of products labeled for some causes of bacterial pneumonia in lactating dairy cows, he says.
So the questions remain: Why are unlabeled drugs being used in lactating dairy cows? Are these farmers intentionally trying to do an end run on the beta-lactam tests that are conducted on every tanker? And what’s the answer? More education? More testing?
Increased testing will undoubtedly get a thorough hearing at the National Conference on Interstate Milk Shipments (NCIMS) meeting in Portland, Ore. next month, says Beth Briczinski, vice president of Dairy and Food Nutrition for the National Milk Producers Federation. The NCIMS governs the Pasteurized Milk Ordinance, which in turn, spells out rules for milk residue testing.
But simply increasing the number of tests run on milk before it is accepted for processing is no simple exercise. First, NCIMS and FDA must decide which drugs to test for. Does one positive Ciprofloxacin residue out of nearly 2,000 samples warrant a national testing program? And if so, how often should it be run?
If you’re going to test for Florfenicol, which accounted for 10 of the 16 positive residues, you need an approved test. Currently, there is no rapid Florfenicol test that gets results in less than 10 minutes. If fact, the only approved Florfenicol test takes 20 to 30 minutes, says Briczinski. That becomes an issue when milk tankers are lined up bumper to grill at dairy processing plants waiting to unload.
The problem, of course, is that if you don’t test, you undermine consumer confidence. A 99.3% safe milk supply is a pretty safe milk supply. But it’s not 100%.
Perhaps consumers will take comfort in the fact that FDA has found no antibiotic residues in the 160,000 samples of retail-ready dairy products it tested over the past four years. Perhaps.
Source: AgWeb
