PS-21 Evaluation of a rapid immunity test for morbidity and mortality in newly received feedlot cattle

Bovine respiratory disease (BRD) is a leading cause of morbidity and mortality in newly received feedlot cattle, requiring rapid and accurate identification for effective management. The nanotechnology-based immunity test (D2Dx) has the potential to immediately identify morbid calves for treatment and decrease the economic loss associated with BRD. The objective was to assess the accuracy of the D2Dx test in quickly detecting morbid calves at risk for BRD upon feedlot arrival. Crossbred cattle (n = 90; initial BW = 213 ± 41 kg) were initially processed, weighed, and allocated to one of 3 soil-surfaced pens. A blood sample was collected from each calf on days 1, 28, and when evaluated for clinical BRD. Cattle displaying clinical BRD symptoms and with a temperature of 40˚C or greater were treated with an antibiotic. The D2Dx immunity test utilizes 10µL of serum and 50µL of pseudo pathogen particle regent mixed thoroughly, and the D2Dx immunity reader evaluates the sample in 30 seconds. Glucose was analyzed in serum from each calf on respective sampling days. Values of D2Dx and glucose concentrations were evaluated using MIXED procedures of SAS. The morbidity status of cattle were defined as 0 = healthy animal; 1 = treated one time for BRD; 2 = treated ≥ 2 times for BRD. Initial D2Dx values were lower (P ≤ 0.01) for morbid cattle compared to healthy cattle upon feedlot arrival. Cattle with morbidity status ≥ 1 had decreased (P ≤ 0.001) D2Dx values than cattle with morbidity status = 0. Similarly, cattle with morbidity status ≥ 2 had decreased (P ≤ 0.05) serum glucose concentrations than cattle with morbidity status ≤ 1. Upon feedlot arrival (d 0), D2Dx values were low for all cattle and increased (P ≤ 0.01) by d 28, implying cattle health status improved by d 28 as D2Dx values increased. Serum glucose concentrations decreased (P ≤ 0.01) for BRD treatments 2 and 3 from d 0 and the first BRD treatment. By d 28, serum glucose concentrations increased (P ≤ 0.01) compared to d 0 and all BRD treatments. In this study, morbidity can be determined by D2Dx values upon arrival. Cattle treated for BRD exhibited lower D2Dx values compared to healthy cattle upon initial arrival. Glucose levels exhibited a similar pattern with decreased values as morbidity status increased. These findings suggest that D2Dx may be an effective technique to identify morbidity status of cattle upon feedlot arrival.