Submitted to: Journal of Animal Science Supplement
Publication Type: Abstract Only
Publication Acceptance Date: 2/10/2005
Publication Date: 3/1/2005
Citation: Thelen, T.M., Taylor, J.B., Loest, C.A., Wang, S., Lewis, G.S. 2005. Splanchnic metabolism of nutrients in response to methionine supplementation in ewes [abstract]. Journal of Animal Science. 83:(Suppl. 1)Paper No.396. Interpretive Summary: Supplemental rumen-protected methionine increased hepatic plasma flow and decreased ammonia flux across the portal-drained viscera.
Technical Abstract: Nulliparous yearling Rambouillet cross ewes (61.9 ± 2.6 kg BW) fitted with chronic indwelling hepatic (H), portal (P), and mesenteric vein and mesenteric artery (A) catheters were used in a randomized design to determine whether dietary methionine affected splanchnic metabolism of nutrients. Treatments were no added methionine (CON; n = 5) or 1.2 g of rumen-protected methionine (MET; Mepron M85, Degussa; n = 6) bolused twice daily at feeding (1.3 kg/d sugar beet pulp pellets, DM basis). Arterial, P, and H blood samples were simultaneously collected before treatment (h 0) and then every 2 h for 12 h. Continuous para-aminohippurate (3% wt/vol; 0.57 mL/min; mesenteric vein) infusion was used to estimate vessel plasma flows. The treatment × time interaction was significant (P = 0.04) for P-A lactate concentration differences. The lactate P-A differences were greater (P = 0.04) for MET at h 12 compared to CON (h 12 = 0.06 vs. -0.07 mM, respectively, SE = 0.04). Methionine P-A and H-P ammonia concentration differences were lower (P < 0.05) than CON (P-A = 0.13 vs.0.22 mM and H-P = -0.11 vs. -0.20 mM, respectively, SE = 0.03). Hepatic plasma flow was greater (P = 0.02) for MET than for CON (140.9 vs. 104.2 L/h, respectively, SE = 7.29); however, treatment did not affect portal and arterial plasma flows. The treatment × time interaction was significant (P = 0.03) for ammonia portal-drained viscera flux, which was lower (P = 0.01) at h 4 for MET compared to CON (h 4 = 9.40 vs. 26.30 mM/h, respectively, SE = 4.60). Methionine treatment did not affect glucose venous-arterial concentration differences or flux. In conclusion, supplemental rumen-protected methionine increased hepatic plasma flow and decreased ammonia flux across the portal-drained viscera.