4 Evaluating the Use of Leukocyte Coping Capacity as a Measure of Acute Stress in Growing Pigs During a Cycling Heating Period

Abstract The study objective was to evaluate leukocyte coping capacity (LCC) as a measure of acute heat stress in growing pigs. LCC method utilizes an artificial challenge procedure on whole blood samples mimic the respiratory burst that is typically observed response pathogen exposure. A reduction size, measured relative light units (RLU) by chemiluminescence, indicates less and greater physiological stress. Forty pigs (mean 66.7 kg BW; range: 54.9-87.5 kg) were assigned 1 2 treatments, 1) thermoneutral (TN; n = 20), where maintained under conditions (range: 18.9-23.7 °C), or 2) (HS; exposed cycling heating period 19.5-28.6 °C) for 48 h. Over each 24 h period, HS housing temperatures rose gradually from 0800-1200 h, at maximal level until 1600 returned 1800 Blood (2 mL) collected pig 0 (0800 h), +4, +8, +24 +48 start experiment. Whole challenged with phorbol 12-myristate 13-acetate induce burst, which using portable luminometer. Data analyzed MIXED SAS 9.4. An hour effect (P < 0.001), RLU values increased linearly throughout experimental period. However, did not differ between TN (57.9 ± 4.1 vs. 55.4 RLU, respectively; P 0.67). Additionally, no treatment interaction any timepoint 0.48). Overall, alter Future studies should whether effective measuring additional properties stress, such chronic periods