U of M Beef Center

Cattle can be many things to a producer at any given time but the fact is they're all the same in the end - food. Steaks, hamburgers burgers, roasts and ribs. They end up on someone's plate thousands of miles away. They are produced with integrity and pride in production. Delivering a safe and quality product is the beef industry's best way to increase beef demand and meet consumer's satisfaction for quality and safety. Let's look at just one of the many quality and safety control measures in the beef production chain-residue testing procedures at harvest plants.

Drug Residue Detection

Guest Author: Ron Torell, University of Nevada Cooperative Extension Livestock Specialist
(Portions of this article were compiled from information provided by Dr. Clell Bagley, DVM with Utah State University, Dr. David Thain, Nevada Department of Agriculture State Veterinarian and Meat Inspectors with the USDA inspection service.)

Licensing a new product

As a company seeks approval from Food and Drug Administration (FDA) for a new antibiotic they have to show data from studies with tissue residues over time, especially kidney, liver, meat, etc. They also have to show FDA a test or tests that will detect the antibiotic or metabolites of it, so FDA knows tests are available for its detection.

The drug company has to show the half-life and its pattern. For most drugs the withdrawal/withholding time will be about 10 times the half-life, which would usually achieve 99 percent plus removal from the animal's body. However, that depends on the curve or pattern of its disappearance and also its presence in specific tissues and additional time may be added. Or, if the pattern is not consistent the drug won't be approved. All of this is why it costs so much to get a new antibiotic approved.

Detection of Drug Residues

How long a drug can be detected depends on how sensitive the test is that is used. Some equipment can detect parts per billion (compared to a few positive kernels of corn in a train car). So, for this test there would be a cut off point and if above that level the carcass would be condemned and if below, it would be passed, etc. But there are some older tests that still work and may be used. One is even for use on live animals. The idea was that a producer could have this test run and then wait longer, if needed before sending the animal to slaughter. For this, urine is collected from the live animal; a small piece of filter paper disk is soaked in the urine and then it is placed onto a plate of agar. On the agar a smear of live bacteria is swabbed all over the surface. The bacteria used is quite sensitive to antibiotics so if any is present in the urine/disk, the bacteria will not grow around the disk, so you know that antibiotic is present in the animal.

There are other tests that have been developed for use in the processing plants with quick turn-around times. One of the tissues most commonly used for testing is the kidney, because it processes the disposal of most drugs and antibiotics. That is why the use of Gentamicin is so strongly discouraged (and it is illegal in food animals). It will retain residues in the kidneys for 18 months.

When veterinarians prescribe drugs for non-label use it is known as extra-label use. The veterinarian then becomes libel for withdrawal times. Producers who use products according to label and sell animals should always maintain accurate records so that if an animal shows residues he/she can demonstrate that the label was followed precisely. If a producer, under the guidance of a veterinarian, uses an extra-label drug, they should maintain even better records including written directions from their veterinarian outlining the withdrawal time.

There is also a variation in animals. For example, if one cow has poor kidney function, she may clear the drug much slower than a healthy animal. Sick animals do not have the organ systems of healthy animals, so there is always the possibility that a treated animal may show residues even if the proper label directions were followed. It is a lot of work to maintain a quality product and be able to demonstrate that a quality assurance program is in place. Remember quality and safety counts!

Random residue testing is used at USDA inspected plants. Additionally, any animal originating from a list of producers who are on the residue violators list is tested. Any "red flag" cattle are automatically tested. These "red flag" carcasses that display inflamed or discolored lungs or other organs, fresh injection sites and unthrifty looking animals are tested. Seasoned meat inspectors are so in tune they can anticipate animals that may have been recently treated. The needles and the product do leave their mark under the skin or in the muscle for quite some time. If a carcass looks suspicious it is side-railed and a quick test is performed at the plant. If the quick test is positive, the tissue is sent forward and an in-depth test is run that can detect residues at finer levels. Producers that get caught with positive animals are "punished" economically by the packer. This encourages them and others to better observe the withdrawal times.

For example, one gondola of hamburger may represent muscle tissue from over 250 animals. Once ground and mixed, one hamburger will represent this same number of cows identified to that gondola. A sample is tested from all these gondolas for e-coli and drug residues. If violations are found the entire batch must be disposed of. The gondola is traced back to the plant of harvest and if the plant kept good records, they can trace it back to the owners of cattle that went into that harvest mix. You can imagine the economic loss to all segments of the industry because of one violation.

As producers we have to recognize that we are not just producing cows but are producing a meat product for someone's table. We have to assure that the beef product meets the quality standards established. Producers need to read and follow labeled directions, keep good records and become a Beef Quality Assurance (BQA) certified producer. Beef quality assurance practices are taught via educational outreach efforts, such as Minnesota's Beef Quality Assurance Program (BQA). This program is an educational program sponsored by the Minnesota Beef Council in cooperation with the University of Minnesota Extension Service, the Minnesota State Cattlemen's Association, the National Cattleman's Beef Association and other industry organizations. The Minnesota Beef Quality Assurance Program is funded by beef check-off investments from Minnesota's beef and dairy producers.

The take home message is to keep good treatment records, read and follow label directions, be conscious of your responsibility to produce a wholesome product and become Beef Quality Assurance certified. For more information on becoming BQA certified contact the Minnesota Beef Council at 952-854-6980.