156 Effect of shipping stress on complete blood counts of backgrounded beef steers

Abstract

The objective of this study was to quantify the effect of shipping to feedyards in western Kansas from the Southeast on the immune response of beef steers using complete blood counts. Angus- and Hereford-sired steers (n = 24, BW = 266.3±24.9 kg) from E.V. Smith Research Center in Shorter, AL, were weaned on June 14, 2018. The following day, blood was collected for analysis. These calves were a subset from a larger project involving grazing. As such, calves were then maintained in drylots for 14 d until grazing was available. Once grazing was initiated, these calves were placed in drylot pens with a diet consisting of dry hay with supplemented with 1% of BW of dried distiller’s grains with solubles. After 80 d, half of the calves were shipped (n = 12, SC) to Hy-Plains Feedyard, LLC. in Montezuma, KS. Immediately prior to shipment, immediately post-shipment, and after 24-hr rest, blood was collected. Blood was also collected from the unshipped calves (UC) at similar time points. Whole blood collected at each time point was analyzed for complete blood counts. The data was analyzed using the Mixed Procedure in SAS. No significant differences (P > 0.05) were detected post-weaning or pre-shipping. Immediately post-shipment, white blood cell, and neutrophil counts were greater in SC while lymphocytes counts were less (P < 0.05) than UC; however, these were not different after 24-hr rest (P > 0.05). Hematocrit and monocyte count were elevated in SC both immediately post-shipping and after 24 hr of rest (P <0.05), while reticulocyte count was lower in SC at those same time points (P < 0.05). Basophil counts were lower in SC at the 24-hr rest time point (P = 0.03). Results of this study indicate that SC did not completely rehydrate after 24 hr of rest and complete blood counts show differences in immune response due to shipping