Why DNA Samples Fail
These common mistakes cause slow response times and bad results.
A lot has changed since DNA testing came to the cattle industry. Hair samples were a beginning. They were fine for what they were. But, genetic testing has taken huge leaps, and Neogen's Stewart Bauck says it's time producers move to Allflex Tissue Sampling Units (TSU).
"These units are the only way to collect high-quality DNA samples. That is important for a consistently fast turnaround with the best possible data," he says. "TSUs are self-contained, have a bar code and are highly amenable to automation and robotics. Because that improves turnaround time, it helps lower costs." Bauck notes Neogen doesn't own shares in Allflex, nor does the company benefit in any way from promoting the use of TSUs.
"Our benefit is that we get a good sample that we can automate," he explains. "We need cattle producers to buy into a good, quality system, because it helps the industry as a whole."
Bauck speaks from experience. He says Neogen's lab, in Lincoln, Nebraska, still gets hair samples in bags. Often, the hair is pulled out of a tail switch with manure still attached. These samples sometimes have no follicles -- important because that's where the DNA is. Blood cards are often no better. Sometimes wet, they often don't have enough blood to test. Some come contaminated with tattoo ink or chemicals applied in processing animals. Two things happen when a lab gets a bad sample: First, DNA testing is delayed. Second, results can be off.
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Jackie Atkins, director of science and education with the American Simmental Association (ASA), says producers who want the best turnaround times need to send all required information when ordering tests. Shortcuts often lead to confusion and delayed results. "This means we need to send follow-up emails or make phone calls to get the necessary information here at ASA," she says. "Misidentification is common when this happens because samples go to the lab without proper identification and paperwork, and they go into a mystery box to be deciphered by the laboratory and ASA staff later."
She says poor sampling techniques often cause testing to fail, adding weeks or even months to a timeline. Common reasons for failed testing include:
> cross-contamination between animals
> fecal matter and dirt in a sample
> insect repellent contaminating a sample
> heat exposure to samples
> extended storage of samples
> no follicles on hair samples
> insufficient blood on a card.
Neogen's Bauck says he has one guarantee when it comes to DNA samples: It's a 100% guarantee. "Send me a bad sample, and I'll send you a bad result. Send me a good sample, and I'll send you a good result."
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