ORIGINAL PAPER
Disappearance of amino acids from the
gastro-intestinal tract of dairy cows fed soyabean
meal or fish meal diets
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1
Institute of Animal Nutrition, Physiology and Metabolism,
Christian-Albrechts- University,
D-24098 Kiel, Germany
2
Moorburger Elbdeich 263,
D-21079 Hamburg, Germany
3
Institute for Ecologically Compatible Animal Husbandry, University of Rostock,
D-18051 Rostock, Germany
Publication date: 1997-02-06
J. Anim. Feed Sci. 1997;6(1):53-69
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ABSTRACT
Four German Friesian cows, fitted with cannulas in the rumen, duodenum and ileum, were fed on
diets containing similar amounts of rumen-degradable organic matter and crude protein, and
soyabean meal or fish meal as the major protein source. The disappearance of organic matter,
nitrogen and amino acids (AA) from the stomachs and from the small and large intestines was
determined. Digestibilities of organic matter, nitrogen and AA in the stomachs were similar for both
diets. A trend was observed for greater disappearance of these components from the small intestine of
cows fed the fish meal diet. The comparison of the AA composition of duodenal digesta with that of
the diets indicated that ruminal fermentation altered the AA profile of fish meal less than that of
soyabean meal. Disappearance of individual AA from the small intestine differed within and between
diets. Preferential disappearance of essential AA from the small intestine compared with non-essential AA was observed. We conclude that the protein value of feedstuffs in terms of absorbed
AA should be evaluated separately for feedstuff and individual AA.
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