Submitted to: American Society of Animal Science Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 2/22/2006
Publication Date: 7/13/2006
Citation: Freetly, H.C., Ferrell, C.L., Archibeque, S.L. 2006. Net flux of A-amino N across splanchnic tissues of ewes during abomasal protein and glucose infusion [abstract]. Journal of Animal Science 84(Suppl. 1):457.
Technical Abstract: Amino acids that enter enterocytes are used for protein synthesis, catabolized, or released into the blood. We hypothesized that providing glucose as an alternate energy source would increase the release of amino acids into the blood. Mature ewes (n = 18; 71.7 +/- 0.7 kg) with permanent catheters in the portal vein, hepatic vein, and abdominal aorta and a cannula in the abomasum were fed a diet of 95% brome hay and 5% soybean meal, as DM (52.2 g/BW kg**0.75). The design was a Youden rectangle with 9 ewes receiving abomasal infusions of either 0 or 3.84 g/h glucose and 1 of 5 abomasal protein infusions (0, 18.1, 36.4, 54.4, or 72.6 mmol amino acids/h, x) in each of 5 periods. The protein was a combination of an isolated soy protein [Ardex (registered trademark) F Dispersible] and cysteine (8.3% by weight). Blood samples were collected 4 through 6 h after infusions were initiated. Net PDV alpha-amino N release increased with protein infusions (P < 0.001; f(x) = 0.346x + 28.2 mmol/h), but the difference between controls and glucose infused ewes was not significant (P = 0.11). Net PDV glucose release was higher (P < 0.001) in ewes receiving the glucose infusion (1.57 +/- 1.51 mmol/h) than control ewes (-12.9 +/- 2.8 mmol/h) and glucose release increased quadratically (P = 0.03; f(x) = -0.026x**2 + 0.1603x mmol/h) in response to protein infusion. Net hepatic alpha-amino N uptake did not differ with glucose infusion (P = 0.21) but increased with protein infusion (P < 0.001; f(x) = 0.275x + 27.3 mmol/h). Net hepatic glucose release decreased (P = 0.005) with glucose infusion (16.9 +/- 2.0 mmol/h) compared to controls (22.5 +/- 3.8 mmol/h) and increased quadratically (P = 0.004) with protein infusion (f(x) = 0.0048x**2 - 0.2148x, mmol/h). This study suggests abomasally infused amino acids were released into the portal blood with an efficiency of ~35%, and that the presence of luminal glucose did not spare amino acids. Reduced hepatic glucose release with glucose infusion indicates that hepatic gluconeogenesis was reduced with increased dietary glucose.