PSIX-19 Leucine supplementation alters immune responses and blood metabolites of lambs exposed to endotoxin. (30th November 2020) - Birkenstock, Bianca
Abstract: This study evaluated effects of supplemental Leu on immune responses and blood metabolites of 29 wether lambs (43.8±10.7 kg) exposed to lipopolysaccharide (LPS). Lambs were fed (1.8% BW daily) a diet of 70% alfalfa hay and 30% corn-based supplement in equal portions twice daily. Lambs were adapted to dietary treatments for 7 days followed by 24-hour collections. Treatments (2×3 factorial) were subcutaneous injection of saline (-LPS) or saline containing LPS to supply 3μg (+LPS) per kg BW on day 7, and daily supplementation of no Leu (NO-LEU), intravenously-infused Leu (IV-LEU), or dietary ruminally-protected Leu (RP-LEU). The IV-LEU and RP-LEU supplied L-Leu at 15mg/kg BW daily. Lambs received jugular catheters 7 days before LPS. Rectal temperature and tumor necrosis factor-α were greater for +LPS than -LPS lambs receiving NO-LEU, and not different between +LPS and -LPS lambs receiving IV-LEU and RP-LEU (LPS×LEU; P≤0.10). Cortisol was greater for +LPS than -LPS lambs 2, 4, and 8 hours after LPS (LPS×hour; P < 0.01). Haptoglobin (24 hours after LPS) was greater for +LPS than -LPS lambs (P < 0.01). Lymphocytes were lower for +LPS than -LPS lambs receiving NO-LEU, and not different between +LPS and -LPS lambs receiving IV-LEU and RP-LEU (LPS×LEU; P = 0.03). Serum glucose was not different at 0, 1, 2, and 4 hours, but lower for +LPS than -LPS lambs 8 hours after LPS (LPS×hour; P = 0.06). Serum Leu, isoleucine, and valine were lower for +LPS than -LPS lambs 4, 8, and 12 hours after LPS (LPS×hour; P < 0.01). Serum Leu was greater for IV-LEU than NO-LEU and RP-LEU at 0 hours, not different among Leu treatments at 1, 2, 4, and 8 hours, and lower for IV-LEU and RP-LEU than NO-LEU 12 hours after LPS (LEU×hour; P < 0.01). These results indicate that Leu supplementation attenuates the inflammatory response to an endotoxin in sheep.