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Enzyme supplementation, degradation and metabolism of three U-14C-labelled cell-wall substrates in the fowl

Published online by Cambridge University Press:  09 March 2007

C. J. Savory
C. J. Savory
Affiliation:
AFRC Institute of Animal Physiology and Genetics Research, Roslin, Midlothian EH25 9PS
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Abstract

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An experimental model is described that was used for assessing in vivo effects in fowls of exogenous enzyme supplementation on the degradation of plant cell walls to metabolizable monosaccharide residues. It was based on tube-feeding U-14C-labelled cell-wall substrates, cellulose, spinach (Spinacia oleracea) or Festuca with and without enzyme treatments, and monitoring recovery of 14C radioactivity in exhaled carbon dioxide and excreta in the following 8 h. Normal digestion of cell-wall polysaccharides by endogenous microbial activity was also studied by pretreating birds with an antibiotic mixture intended to deplete their intestinal microflora. The results of this pretreatment appeared to confirm the existence of microbial degradation of cellulose in (conditioned) fowls. Judging from differences in 14CO2 production, effects of exogenous enzyme additions were greatly enhanced with all substrates by combining them with a wet pretreatment, thereby increasing the time-period available for them to act in aqueous conditions. However, estimations of digestibilities of cellulose, hemicellulose and pectin with dry and wet treatments, based on recovery of 14C in excreta, indicated that it was only cellulose digestion that was improved by the wet pretreatment. This suggests that degradation of cellulose, which appeared to be slowest, was limited by the dry treatments, whereas that of hemicellulose and pectin was not. Respective digestibilities of these three cell-wall components, from all treatments combined, were in the proportions 1:1.5:4·2.

Keywords

Plant cell-wall substratesCell-wall degradationEnzyme supplementationFowl
Type
Effects of Complex Carbohydrates on Nutrient Absortion
Information
British Journal of Nutrition , Volume 67 , Issue 1 , January 1992 , pp. 91 - 102
Copyright
Copyright © The Nutrition Society 1992

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