HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Ellis, W. C. Articles by Matis, J. H. Search for Related Content PubMed PubMed Citation Articles by Ellis, W. C. Articles by Matis, J. H.

Validity of specifically applied rare earth elements and compartmental models for estimating flux of undigested plant tissue residues through the gastrointestinal tract of ruminants

W. C. Ellis^*,1, M. J. Wylie^,2 and J. H. Matis

^* Department of Animal Science, Texas A&M University, College Station 77843-2471; and Department of Animal Science, University of Wisconsin, Madison 53706; and Department of Statistics, Texas A&M University, College Station 77843-2471

¹ Correspondence:
(phone: 979-845-5063; fax: 979-845-5292; E-mail:
w-ellis{at}tamu.edu).

The validity of using rare earth elements as flow markers of undigested residues was evaluated by comparing mean gastrointestinal residence time (GMRT) of rare earths specifically applied to cottonseed hulls (CSH) to that of the indigestible fiber of CSH. Feces were collected from five lambs fed a mineral supplemented diet of CSH containing 52 g CP/kg DM and five lambs fed a CSH plus cottonseed meal diet (CSH+CSM) containing 123 g CP/kg DM. Rare earth elements (La, Yb, and Tb) specifically bound to CSH were included in the diet for a 5-d period and then deleted from the diet for a 3-d period. Following the last fecal collection, lambs were slaughtered for collection of digesta from segments of the gastrointestinal tract. Potentially indigestible NDF (PIF) was determined in diets and digesta from each segment of the gastrointestinal tract. Mean turnover rate, time delay, and GMRT for each rare earth element was estimated by fitting an age-dependent compartment model to profiles of markers appearing in the feces (compartmental model-marker method, CMM). The GMRT also was computed by the indigestible entity pool dilution method (IEPD) as grams of PIF in sampled segment/mean intake rate of PIF proceeding slaughter, g/h. The GMRT computed by the CMM and the IEPD methods did not significantly (P < 0.05) differ (99.6 vs 94.8 h and 58.9 vs 59.5 h for CMM vs IEPD and CSH and CSH+CSM diets, respectively). Regression of GMRT estimated for rare earths vs PIF yielded a highly significant regression (P = 0.001) with a regression coefficient of 0.94 ± 0.016. It was concluded that rare earth elements applied to specific feeds are valid flow markers for the undigested residues derived from such marked feeds.

Key Words: Digesta • Flow • Markers • Models

This article has been cited by other articles:

				C. Lanzas, L. O. Tedeschi, S. Seo, and D. G. Fox Evaluation of Protein Fractionation Systems Used in Formulating Rations for Dairy Cattle J Dairy Sci, January 1, 2007; 90(1): 507 - 521. [Abstract] [Full Text] [PDF]

				L. S. Walz, W. C. Ellis, T. W. White, J. H. Matis, H. G. Bateman, C. C. Williams, J. M. Fernandez, and L. R. Gentry Flow paths of plant tissue residues and digesta through gastrointestinal segments in Spanish goats and methodological considerations J Anim Sci, February 1, 2004; 82(2): 508 - 520. [Abstract] [Full Text] [PDF]