Comparison of Plasma Oxidative Status Biomarkers in Neonatal Dairy Calves during Summer and Fall Seasons

Abstract

Heat stress impairs normal physiology and behavior in dairy calves. Oxidative status can be evaluated using plasma markers of oxidative stress. Studies on effects of heat stress on oxidative status as a result of exposure to summer weather in dairy calves are lacking. The purpose of this study was to compare the activity or concentrations of plasma markers of oxidative stress of dairy calves raised in the summer, compared to those raised in the fall in a single calendar year. Thirty-four Jersey calves born in summer and 33 born in fall, aged 24-48 hours age were enrolled. Plasma glutathione peroxidase (GSH-Px), superoxide dismutase (SOD) activities, and concentrations of thiobarbituric acid reactive substances (TBARS) were determined. Temperature humidity index was also determined. Mean activities of GSH-Px and SOD were higher for calves born and raised in summer, compared to calves born in fall. Concentrations of TBARS were not consistently different in calves born and raised in summer, compared to calves born in fall. Study results suggest condition of oxidative stress of calves born and raised in summer compared to calves born in fall. Results of this study suggest that plasma GSH-Px and SOD may be useful in monitoring calves for evidence of oxidative stress. Potential application from the results of this study on farms contracted to raise calves is to objectively monitor calves’ oxidative status upon arrival from the farm of origin, or at weaning when calves are comming led in larger groups during different seasons of year, and to adjust housing conditions accordingly