Passage kinetics of concentrates in dairy cows measured with carbon stable isotopes

D. Warner, J. Dijkstra, S. Tamminga, W.F. Pellikaan

Research output: Contribution to journalArticleAcademicpeer-review

6 Citations (Scopus)


Fractional passage rates form a fundamental element within modern feed evaluation systems for ruminants, but knowledge on feed-specific fractional passage is largely lacking. Commonly applied tracer techniques based on externally applied markers, such as chromium-mordanted neutral detergent fibre (Cr-NDF), have been criticised for behaving differently to feed particles. This study describes the use of the carbon stable isotope ratio (13C : 12C) as an internal digesta marker to quantify the fractional passage rate of concentrates through the digestive tract of dairy cows. In a crossover study, five dairy cows were fed low (24.6%) and high (52.6%) levels of concentrates (dry matter (DM) basis) and received a pulse-dosed Cr-NDF and 13C isotopes. The latter was administered orally by exchanging part of the dietary concentrates of low 13C natural abundance with a pulse dose of maize bran-based concentrates of high 13C natural abundance. Fractional passage rates from the rumen (K1) and from the large intestine (K2) were determined from faecal marker concentrations of Cr-NDF and of 13C in the DM (13C-DM), NDF (13C-NDF) and neutral detergent soluble (13C-NDS). No differences in K1 estimates were found for the two concentrate levels fed but significant differences between markers (P
Original languageEnglish
Pages (from-to)1935-1943
Issue number12
Publication statusPublished - 2013


  • neutral detergent fiber
  • rumen
  • digestion
  • marker
  • model
  • ruminants
  • excretion
  • ratios
  • impact
  • matter

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