Assessment of duodenal amino acid profile in dairy cows by the in situ method

H. Tagari*, A. Arieli, S. Mabjeesh, I. Bruckental, S. Zamwell, Y. Aharoni

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

17 Scopus citations


In situ evaluation of the duodenal amino acid (AA) profile was attempted in a 4 × 4 Latin square study using four lactating Holstein cows fitted with ruminal and duodenal cannulas. Dietary supplemental crude protein (CP) sources, making up 40% of the dietary CP, were: soybean meal, cottonseed meal, corn gluten meal or urea. Duodenal flow of organic matter (OM) and CP was determined in vivo by means of constant infusion of ytterbium and chromium, and predicted in situ from rumen degradation. Purines were used as microbial markers. In situ calculation of the AA profile, expressed as g AA in 100 g of total AAs, was based on the composition of AA in feed and in isolated bacteria as well as on in situ rumen degradation of OM and CP. The AA profile in the duodenum when assessed in vivo was affected by the nature of the supplemental protein; in situ assessment of the AA profile resulted in comparable profiles. The data are interpreted to suggest that the in situ method enables prediction of the profile of AA (g AA/100 g total AA) flowing to the duodenum, and that the undegraded portion of supplemented protein affects that profile.

Original languageAmerican English
Pages (from-to)13-22
Number of pages10
JournalLivestock Production Science
Issue number1
StatePublished - Apr 1995


  • Dacron bag
  • Dairy cow
  • Duodenal amino acid


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