Evaluating plasma oxidative measures in beef calves supplemented with methionine and challenged with lipopolysaccharide

Introduction The present study evaluated oxidative stress indicators in plasma of beef calves supplemented with a rumen-protected methionine (L0 = receiving ration top-dressed with a ground corn carrier, L1 = receiving ration top-dressed with 10.0 g of rumen-protected methionine supplement in a ground corn carrier, L2 = receiving ration top-dressed with 20.0 g of rumen-protected methionine supplement in a ground corn carrier) and administered lipopolysaccharide (LPS). An additional objective evaluated the effect of LPS on plasma metabolites. Methods Following an initial feeding period (40 d), steers (n = 32; 379 kg ± 30.7) were intravenously administered LPS (0.25 μg/kg BW). Blood was collected via jugular catheter at -2, 0, 2, 4, 6, 8, 10, 12, 18, 24, 36, and 48 h relative to LPS administration (0 h). Plasma was analyzed for amino acid (AA) concentrations, ferric-reducing antioxidant power (FRAP), thiobarbituric reactive substances (TBARS), and reactive oxygen species (ROS). Metabolomic analysis occurred for control cattle at -2, 2, and 8 h. Results and discussion Plasma AA asparginine and methionine were increased with supplementation ( P < 0.01). The greatest FRAP values were observed at -2, 0, 2, 36, and 48 h ( P < 0.001). At 6 and 8 h, FRAP decreased to their lowest values ( P < 0.001). Amount of TBARS increased at 2 h but declined at 4h ( P < 0.001). A treatment × time interaction occurred for ROS ( P < 0.001). At 2 h, ROS was greatest in L0 cattle, least in L2, and intermediate in L1 but declined at 4 h in all treatments ( P < 0.001). Values peaked at 6 h for L1 and L2 cattle, followed by a decline at 8 h ( P < 0.001). Values for L0 cattle were similar from 4 to 6 h ( P = 0.371) but increased at 8 h ( P < 0.001). Finally, L0 plasma metabolites present at -2 h segregated from those present at 2 and 8 h ( P < 0.05). Differences were primarily driven by taurocholic acid, LysoPE, butyric acid, acitretin, and tauromuricholic acid. These data demonstrate that LPS may alter oxidative stress indicators and plasma metabolites. However, methionine supplementation may mitigate oxidative stress.