PSXV-30 - Late-Breaking: Oxidative stress biomarkers in blood plasma and pre-rigor tissues of beef cattle induced by hydrogen peroxide

This study examined the oxidative stress biomarkers in blood plasma and pre-rigor tissues of beef heifers induced by hydrogen peroxide. Cattle (365 ± 38 kg; n = 18) were supplemented with ground corn and soybean hulls while grazing cool and warm-season pastures, then shipped and finished at a commercial feedlot in Iowa. Animals were blocked into three groups based on initial clusters of oxidative stress markers. Two treatments of either 20 mg hydrogen peroxide/kg BW (OX, n = 9) or 10 mL of saline (CON, n = 9) were equally and randomly assigned to animals within each group. On the day before slaughter, the OX and CON treatments were administered intravenously through the jugular vein. Blood samples were collected immediately before (T0) and 90 min after (T90) treatment and centrifuged into plasma and pre-rigor muscles were collected at the neck (splenius) during slaughter; both were frozen in liquid nitrogen and stored at -80ºC. Blood plasma and muscle tissues were analyzed for total antioxidant capacity (TAC), thiobarbituric acid reactive substances (TBARS), and glutathione peroxidase activity (GPx). Muscle tissues were also analyzed for glutathione (GSH). The data were analyzed as a randomized complete block design with repeated measures with treatment, time, and their interaction as fixed effects. Oxidative stress treatment did not affect TAC and TBARS values (P ≥ 0.137). However, T0 plasma had 0.47 mM less (P = 0.009) and 5.84 μM more (P < 0.001) of TAC and TBARS, respectively, than T90 plasma. Although CON had 27.73 nmol/min/mL more GPx at T0 (P = 0.039), such activity did not differ in both groups at T90 (P = 0.542). Treatment did not affect oxidative stress markers in pre-rigor tissues (P ≥ 0.184). Inducing oxidative stress by hydrogen peroxide had minimal effects on biomarkers in blood and muscle tissues.