Testing out a Theory

Summers past would find Emily Schwake on a dairy farm in Texas, working with heifers in Arizona, at a beef feed lot in Nebraska, observing at a small animal clinic or with a large animal veterinarian in her home state of Iowa.

This summer however, Schwake wasn’t out in the field. Instead she spent the summer testing a hypothesis of an Iowa State University College of Veterinary Medicine clinician.

“This was definitely a new experience for me,” said Schwake, a second-year veterinary medicine student. “I’m more of a farm worker but I wanted to see how different parts of the diagnostic laboratory operate and this was a good way to do that.

“I’m a firm believer in getting as much hands-on experience outside of the classroom as I can and I thought I’d give working in a university atmosphere a try this summer.”

Schwake participated in the Dairy Veterinary Internship Program (DVIP), which gives Iowa State students the opportunity to collaborate with leading veterinarians in the dairy veterinary medicine industry.

The second-year student worked with Dr. Pat Gorden, a clinical professor in veterinary diagnostic and production animal medicine. Gorden wanted to test out his theory that some on-farm antibiotic residue milk test kits were returning false positive results on an antibiotic commonly used to treat mastitis, an infection of the udder in dairy cows.

The test kits were used to determine levels of antibiotics in the milk, specifically looking at once particular antibiotic used to treat mastitis (udder infection) in dairy cattle; cephapirin. The test kits are intended to be used to measure antibiotic levels in bulk milk tanks used to store milk from the cows on the farm. If residue levels are above the FDA approved limit, it will result in all the milk being dumped from that tank.

The economic impact of such a situation is so concerning to dairy farmers, some are now using the test kits on the milk of one animal, hoping to find concerns before that animal’s milk is put in with the entire herd’s.

Schwake says the inappropriate use of the test kits may be causing false readings. This summer she spiked milk samples with designated levels of antibiotics to see results of the test kits.

“I essentially ‘tested’ the reactions of the milk test kits,” she said. “While we just have preliminary results, if the study shows vast differences between readings and reality, we will move forward to the next step.”

The next step is to see what possibly needs to be changed in the test kits to give more accurate antibiotic residue readings. This may include developing individual cow test kits or any number of new directions.

“A rejected tank of milk can potentially shut down a farm,” Schwake said. “That would be a huge economic hit for small farmers, really any farmers.”