Jugular infusion of arginine has a positive effect on antioxidant mechanisms in lactating dairy cows challenged intravenously with lipopolysaccharide

摘要

The main purpose of this work was to evaluate the effects of jugular L-arginine infusion on antioxidant mechanisms in lactating dairy cows challenged intravenously with lipopolysaccharide (LPS). Eight multiparous Holstein cows (609 +/- 32 kg) at midlactation were randomly assigned to 5-d jugular infusions of Control (saline), Arginine (Arg, 18 g/d), LPS (0.2 mu g/kg BW per day), and LPS + Arginine (0.2 mu g/kg BW per day of LPS and 18 g/d of Arg) in a replicated 4 x 4 Latin square design with 4 infusion periods separated by 10-d. Jugular solutions of saline, Arg, LPS, and LPS + Arg were continuously infused using peristaltic pumps for approximately 6 h/d. Jugular vein serum samples were obtained on the last day of each infusion period before infusion (0 h) and at 3-and 6-h postinfusion. Compared with LPS treatment, Arg infusion increased the total antioxidant capacity and activity of glutathione peroxidase, but decreased malondialdehyde concentration (P 0.05). The concentration of nitric oxide in serum and the activity of nitric oxide synthase were greater in LPS treatment compared with saline and Arg (P 0.05). The Arg treatment significantly increased the serum insulin concentration at 3-h postinfusion compared with the saline treatment (P 0.05), and that of LPS and LPS + Arg treatments were in between Arg and LPS treatments. No treatment effect was observed on the activities of superoxide dismutase and catalase (P 0.05). In conclusion, enhancing the supply of Arg during an inflammatory challenge enhances antioxidant mechanisms in lactating dairy cows.