title: Route of tracer administration does not affect ileal endogenous nitrogen recovery measured with the 15N-isotope dilution technique in pigs fed rapidly digestible diets.
abstract: The (15)N-isotope dilution technique ((15)N-IDT), with either pulse-dose oral administration or continuous i.v. administration of [(15)N]-l-leucine (carotid artery), both at 5 mg/(kg body weight . d), was used to measure ileal (postvalve T-cecum cannula) endogenous nitrogen recovery (ENR) in pigs (9 +/- 0.6 kg). Diets were cornstarch, enzyme-hydrolyzed casein with no (control) or high (4%) content of quebracho extract (Schinopsis spp.) rich in condensed tannins. Blood was sampled from a catheter in the external jugular vein. Mean plasma (15)N-enrichment at d 8-10 was higher (P = 0.0009) after i.v. than after oral administration [0.0356 vs. 0.0379 atom% excess (APE)]. Plasma (15)N-enrichment for i.v. infused pigs was 0.01117 APE higher (P < 0.0001) and for orally dosed pigs 0.0081 APE lower (P < 0.0001) at 11 h postprandial compared with 1 h postprandial. Apparent ileal N digestibility was higher (P < 0.0001) for the control (85.5%) than for the quebracho diet (69.5%). ENR was calculated from the ratio of (15)N-enrichment of plasma and digesta. The ENR for the quebracho diet was approximately 300% higher than for the control diet (6.03 vs. 1.94 g/kg dry matter intake, P < 0.001). The real N digestibility (92.2 +/- 0.4%) was equal for both diets (P = 0.1030) and both tracer methods (P = 0.9730). We concluded that oral administration of [(15)N]leucine provides reasonable estimates of ENR in pigs fed semipurified diets with high or low content of tannins; however, one must be careful in extrapolating this conclusion to studies with other protein sources or feeding frequencies.
authors.affiliation: Animal Nutrition Group, Wageningen Institute of Animal Sciences (WIAS), Wageningen University and Research Centre, 6700 AH Wageningen, The Netherlands. Carina.Steendam@wur.nl
authors.forename: C A Carina
authors.initials: CA
authors.lastname: Steendam
authors.forename: Martin W A
authors.initials: MW
authors.lastname: Verstegen
authors.forename: Seerp
authors.initials: S
authors.lastname: Tamminga
authors.forename: Huug
authors.initials: H
authors.lastname: Boer
authors.forename: Marianne
authors.initials: M
authors.lastname: van 't End
authors.forename: Berthe
authors.initials: B
authors.lastname: Verstappen
authors.forename: William R
authors.initials: WR
authors.lastname: Caine
authors.forename: G Henk
authors.initials: GH
authors.lastname: Visser
mesh_terms: D027926:Anacardiaceae / Q000737:chemistry; D000818:Animals; D002364:Caseins; D004032:Diet; D004063:Digestion; D007082:Ileum / Q000378:metabolism*; D007201:Indicator Dilution Techniques; D009584:Nitrogen / Q000378:metabolism*; D009587:Nitrogen Isotopes / Q000008:administration & dosage* / Q000097:blood; D013213:Starch; D013552:Swine / Q000378:metabolism*; D013634:Tannins / Q000008:administration & dosage
chemical_list: D002364:Caseins; D009587:Nitrogen Isotopes; D013634:Tannins; D013213:Starch; D009584:Nitrogen