title: Disappearance and appearance of an indigestible marker in feces from growing pigs as affected by previous- and current-diet composition.
abstract: BACKGROUND
  Indigestible markers are commonly utilized in digestion studies, but the complete disappearance or maximum appearance of a marker in feces can be affected by diet composition, feed intake, or an animal's BW. The objectives of this study were to determine the impact of previous (Phase 1, P1) and current- (Phase 2, P2) diet composition on marker disappearance (Cr) and appearance (Ti) in pigs fed 3 diets differing in NDF content.
  
  
  RESULTS
  When pigs were maintained on the 25.1, 72.5, and 125.0 g/kg NDF diets, it took 5.1, 4.1, and 2.5 d, respectively, for Cr levels to decrease below the limit of quantitation; or 4.6, 3.7, or 2.8 d, respectively, for Ti to be maximized. These effects were not, however, independent of the previous diet as indicated by the interaction between P1 and P2 diets on fecal marker concentrations (P< 0.01). When dietary NDF increased from P1 to P2, it took less time for fecal Cr to decrease or fecal Ti to be maximized (an average of 2.5 d), than if NDF decreased from P1 to P2 where it took longer for fecal Cr to decrease or fecal Ti to be maximized (an average of 3.4 d).
  
  
  CONCLUSIONS
  Because of the wide range in excretion times reported in the literature and improved laboratory methods for elemental detection, the data suggests that caution must be taken in considering dietary fiber concentrations of the past and currently fed diets so that no previous dietary marker addition remains in the digestive tract or feces such that a small amount of maker is present to confound subsequent experimental results, and that marker concentration have stabilized when these samples are collected.
authors.affiliation: Department of Animal Science, Iowa State University, Ames, 50010 USA.
authors.forename: Brandy M
authors.initials: BM
authors.lastname: Jacobs
authors.affiliation: Department of Animal Science, Iowa State University, Ames, 50010 USA.
authors.forename: John F
authors.initials: JF
authors.lastname: Patience
authors.affiliation: Department of Animal and Food Sciences, University of Kentucky, Lexington, 40546 KY USA.
authors.forename: Merlin D
authors.initials: MD
authors.lastname: Lindemann
authors.affiliation: Department of Animal Science, Iowa State University, Ames, 50010 USA.
authors.forename: Kenneth J
authors.initials: KJ
authors.lastname: Stalder
authors.affiliation: USDA-ARS-National Laboratory for Agricultural and the Environment, Ames, 50010 IA USA.
authors.forename: Brian J
authors.initials: BJ
authors.lastname: Kerr
keywords: Adaptation; Digestibility; Fiber; Indigestible marker; Pig