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Integration of in vitro parameters by mechanistic modelling to predict recycling of microbial nitrogen in the rumen

Published online by Cambridge University Press:  27 February 2018

J. Dijkstra ,
J. France  and
S. Tamminga
J. Dijkstra
Affiliation:
Wageningen Institute of Animal Sciences, Animal Nutrition Centre, Marijkeweg 40, 6709 PG Wageningen, The Netherlands
J. France
Affiliation:
Institute of Grassland and Environmental Research, North Wyke, Okehampton, Devon EX20 2SB
S. Tamminga
Affiliation:
Wageningen Institute of Animal Sciences, Animal Nutrition Centre, Marijkeweg 40, 6709 PG Wageningen, The Netherlands
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Extract

In protein evaluation systems for ruminants, the microbial protein supply is calculated from the amounts of rumen degradable organic matter and nitrogen (N) using empirical equations. A variable part of the rumen synthesized microbial protein does not reach the duodenum but is recycled within the rumen (review Firkins, 1996). Since energy is required for its re-synthesis and degraded microbial protein is subject to deamination, the efficiency of substrate conversion into microbial protein in the rumen is affected by microbial recycling. Rumen protozoa have a major impact upon this recycling through engulfment of micro-organisms and autolysis. In vitro, bacterial protein breakdown is proportionately reduced by some 0·9 upon removal of protozoa (Wallace and McPherson, 1987). Defaunation of the rumen increases the efficiency of microbial protein synthesis in vivo significantly (review Jouany et al., 1988).

Type
Complex rumen transformations
Information
BSAP Occasional Publication , Volume 22: In vitro techniques for measuring nutrient supply to ruminants , 1998 , pp. 158 - 160
Copyright
Copyright © British Society of Animal Science 1998

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