Metaphylaxis, or mass treatment upon arrival, has demonstrated effectiveness in reducing morbidity in high-risk feeder cattle. However, the system inevitably treats some percentage of healthy cattle, generating significant financial costs.

A quick and accurate test for quantifying disease risk at the processing chute could allow more selective, targeted treatment, improving animal health while reducing antibiotic use. According to Advanced Animal Diagnostics (AAD), the new QScout BLD diagnostic test could help feedyards achieve that goal.

AAD recently hosted a webinar, in which the company’s CEO, Joy Drach, and the VP for trials Mitch Hockett, PhD, outlined results of a recent Nebraska feedyard trial demonstrating a potential 87% reduction in arrival antibiotic use by selectively treating animals compared to metaphylaxis.

In this trial, researchers randomly sorted 1,554 feeder cattle into groups either receiving or not receiving antibiotic treatment upon arrival. Using the QScout BLD test, they measured the leukocyte levels (neutrophils and lymphocytes) as an indicator of disease risk.

Out of the 1,554 cattle in the trial, 205 showed abnormal leukocyte levels upon arrival. About half of those were in the treated group and half untreated. Over the first 40 days on feed, the abnormal cattle gained about 1/3 pound less per day than those with normal leukocyte levels. Among the cattle with abnormal leukocyte levels at arrival, those receiving antibiotic treatment had significantly lower morbidity, heavier carcass weights and higher USDA Quality Grades than those that were not treated. In this trial, high lymphocyte levels were associated with the greatest differences in average daily gains and high neutrophil levels were associated with the greatest differences in pull rates.

Using an average treatment cost of $17 to $25 per head, Hockett notes that a yard mass-treating 10,000 head of cattle would spend $170,000 to $250,000. If that yard could treat just 20% of arrivals based on chute-side diagnostics, they would spend between $34,000 and $50,000 to treat 2,000 head, for a savings of $136,000 to $200,000, minus testing costs. In the Nebraska trial, 13% of the cattle were diagnosed as abnormal and would have been treated based on the chute-side diagnostic test.

Hockett says the QScout BLD test uses a single drop of blood collected from the calf during processing. The blood sample is then transferred to a single-use QScout BLD test and inserted into AAD’s QScout Cattle Lab, a portable lab-in-a-box diagnostic platform. The Internet-enabled lab measures leukocyte levels and provides a simple green or red light indicating normal or abnormal. The test currently takes about 43 seconds to generate a result. Price for the feedyard diagnostic testing system has not been finalized, but a similar system currently in use in dairies costs around $18,000.

The recorded webinar now is available for viewing.