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No easy solution for the fractionation of faecal nitrogen in captive wild herbivores: results of a pilot study


Schwarm, A; Schweigert, M; Ortmann, S; Hummel, J; Janssens, G P J; Streich, W J; Clauss, M (2009). No easy solution for the fractionation of faecal nitrogen in captive wild herbivores: results of a pilot study. Journal of Animal Physiology and Animal Nutrition, 93(5):596-605.

Abstract

Faecal nitrogen (FN) concentration is used as a marker for habitat quality and digestive efficiency in free-ranging herbivores. In herbivores, FN can be separated into undigested plant N (analysed as the N concentration of the neutral detergent residue) and metabolic faecal N (MFN). It has been suggested that by differential analysis of the faecal fibre-bound N, the MFN fraction can be further split into a bacterial N and an endogenous N fraction [Hesta et al., Br. J. Nutr. 90 (2003) 1007]. We applied these methods to 96 faecal samples of 48 mammalian herbivore species from zoos. Species were grouped into coprophageous and noncoprophageous hindgut fermenters and ruminating and non-ruminating foregut fermenters. Diet was not controlled. The FN decreased with body mass, possibly reflecting higher proportions of concentrates in diets of smaller animals. The proportion of MFN increased with FN, indicating that higher quality food might enhance the gastrointestinal bacterial flora. The only outlier to this pattern was the lesser panda (Ailurus fulgens), confirming the low relevance of fermentative digestion in this herbivorous ‘carnivore’. No relevant differences between the four digestion types were noted. The proportion of endogenous faecal N (32–80% of FN) was always higher than that of bacterial faecal N (7–30%), which contradicts basal understanding of herbivore digestive physiology. Thus, the method of Hesta et al. (2003) does not appear applicable to herbivores. While the results do not exclude the possibility that detailed differences might occur between digestion types, they indicate a high degree of similarity between herbivores that rely on bacterial fermentation, regardless of their digestion type, with respect to metabolic faecal losses.

Faecal nitrogen (FN) concentration is used as a marker for habitat quality and digestive efficiency in free-ranging herbivores. In herbivores, FN can be separated into undigested plant N (analysed as the N concentration of the neutral detergent residue) and metabolic faecal N (MFN). It has been suggested that by differential analysis of the faecal fibre-bound N, the MFN fraction can be further split into a bacterial N and an endogenous N fraction [Hesta et al., Br. J. Nutr. 90 (2003) 1007]. We applied these methods to 96 faecal samples of 48 mammalian herbivore species from zoos. Species were grouped into coprophageous and noncoprophageous hindgut fermenters and ruminating and non-ruminating foregut fermenters. Diet was not controlled. The FN decreased with body mass, possibly reflecting higher proportions of concentrates in diets of smaller animals. The proportion of MFN increased with FN, indicating that higher quality food might enhance the gastrointestinal bacterial flora. The only outlier to this pattern was the lesser panda (Ailurus fulgens), confirming the low relevance of fermentative digestion in this herbivorous ‘carnivore’. No relevant differences between the four digestion types were noted. The proportion of endogenous faecal N (32–80% of FN) was always higher than that of bacterial faecal N (7–30%), which contradicts basal understanding of herbivore digestive physiology. Thus, the method of Hesta et al. (2003) does not appear applicable to herbivores. While the results do not exclude the possibility that detailed differences might occur between digestion types, they indicate a high degree of similarity between herbivores that rely on bacterial fermentation, regardless of their digestion type, with respect to metabolic faecal losses.

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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:05 Vetsuisse Faculty > Veterinary Clinic > Department of Small Animals
Dewey Decimal Classification:570 Life sciences; biology
630 Agriculture
Date:October 2009
Deposited On:18 Sep 2009 11:44
Last Modified:05 Apr 2016 13:20
Publisher:Wiley-Blackwell
ISSN:0931-2439
Publisher DOI:10.1111/j.1439-0396.2008.00842.x
Permanent URL: http://doi.org/10.5167/uzh-20645

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