Give yourself a pat on the back.
According to the National Milk Drug Residue Data Base, you’re doing a good job keeping drug residues out of the milk supply. In fiscal year 2011, a mere 0.021 percent of all truckloads of milk tested positive for animal drug residues. By the numbers, that’s 671 positive out of 3.183 million samples.
That also is a decline of 70 percent over the last 10 years, says Jamie Jonker, vice president of scientific and regulatory affairs for the National Milk Producers Federation.
As of press time in mid-February, the fiscal 2012 report was not yet available. However, if the numbers follow trend, you can expect more good news.
“We’ve seen continuous decline since 1996,” Jonker says. “It’s a small decline each year, but over time that small decline becomes a large decline.”
This is all well and good, but don’t become complacent about residue prevention. Over the years, the sensitivity of drug-residue screening tests has increased, not to mention the regulations governing how drugs can be used in dairy animals. Nowadays, what was once undetectable is now detectable — and even grounds for a residue violation.
More sensitive, more risk
For certain drugs, an increase in the sensitivity of a milkresidue screening test is not a big deal. The U.S. Food and Drug Administration has established “safe” or tolerance levels for a number of animal drugs. That level doesn’t change, regardless of a test’s sensitivity.
“If a residue is found in milk and it’s below that safe or tolerance level, it’s not a violation,” Jonker says. “It’s not a safety issue and that milk is acceptable for processing.”
However, for other drugs, there is zero tolerance for residues in milk, which means any detectable level is a violation, Jonker says. For those drugs, greater testing sensitivity is a big deal because it makes residue detection possible at increasingly smaller levels.
Bottom line: The more sensitive a test is, the more critical it becomes to strictly follow withdrawal times. Always adhere to approved routes of administration, drug dose and treatment duration. Failure to do so can affect the rate of elimination of a drug and result in costly residue violations.
Milk residue survey results coming soon
Residue detection in milk will likely garner even more attention in the coming months. At press time in mid-February, the FDA was getting ready to release results of a milk-residue sampling project that began in January 2012.