Submitted to: American Society of Animal Science Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 2/23/2005
Publication Date: 7/28/2005
Citation: Archibeque, S.L., Freetly, H.C., Ferrell, C.L. 2005. Total splanchnic flux of nutrients in wethers fed oscillating crude protein diets [abstract]. Journal of Animal Science. 83(Supplement 1):396.
Technical Abstract: We hypothesized that oscillating dietary CP would improve ruminant N retention by increasing nutrient flux compared to static dietary CP regimens. Chronic indwelling catheters were surgically implanted in a mesenteric artery, mesenteric vein, hepatic vein, and portal vein of 18 growing Suffolk x Dorsett wethers (44.65 ± 3.59 kg). Wethers had ad libitum access to the following diets: 1) Low (9.91% CP), 2) Med (12.5% CP), or 3) Low and High (14.19% CP) oscillated on a 48 h interval (Osc). Dry matter intake tended (P = 0.09) to be greater in Osc (1,313 g/d) than Low (987 g/d) fed wethers, but not those fed Med (1,112 g/d). Nitrogen intake was not different between Osc (25.3 g/d) and Med (22.2 g/d) fed wethers but was reduced (P < 0.01) in wethers fed Low (16.0 g/d). Osc wethers (6.66 g/d) retained more (P < 0.02) N than either Low (3.20 g/d) or Med (3.96 g/d) fed wethers. There were no discernable alterations in nutrient flux over the 4 d oscillation period (Time x Diet interaction, P > 0.15). Arterial blood flow was lower (P = 0.02) in Osc (32 L/h) fed wethers than either Med (48 L/h) or Low (69 L/h) fed wethers. Net release of alpha-amino N by the portal-drained viscera (PDV) did not differ (P = 0.44) among the Low (35.9 mmol/h), Med (34.3 mmol/h), or Osc (53.0 mmol/h) fed wethers. Net PDV release of ammonia N was lower (P = 0.03) in Low fed wethers, which was accompanied by a similar decrease (P = 0.02) in hepatic ammonia N uptake. Urea N concentrations tended (P < 0.08) to be reduced in arterial (1.67 mM), portal (1.58 mM), and hepatic (1.70 mM) blood in wethers fed the Low diet compared to Med or Osc fed wethers. However, net release of urea N did not differ across the PDV(P = 0.30), liver (P = 0.76), or total splanchnic tissues (P = 0.42). Portal net uptake of glutamine was greater (P < 0.01) in the Low (7.6 mmol/h) fed wethers than those fed the Med (3.46 mmol/h) and Osc (3.08 mmol/h) diets. There were no alterations (P > 0.15) in glutamate, glucose, lactate, or oxygen flux. Although diet effects on PDV and splanchnic release of alpha-amino N were not significant, numerical differences were consistent with observed patterns of N retention.