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Comparative selective retention of particle size classes in the gastrointestinal tract of ponies and goats


Hummel, J; Scheurich, F; Ortmann, S; Crompton, L A; Gerken, M; Clauss, Marcus (2018). Comparative selective retention of particle size classes in the gastrointestinal tract of ponies and goats. Journal of Animal Physiology and Animal Nutrition, 102(2):429-439.

Abstract

There is a discrepancy in the literature on potential digesta separation mechanisms in horses, with both a selective retention of fine and of large particles postulated in different publications. To assess the net effect of such mechanisms, we fed ponies on a hay-only diet a pulse dose of whole (unchopped) marked hay together with a solute marker, collected faeces on a regular basis, measured marker concentrations in whole faeces and in their large (2.0–16 mm), medium (0.5–1.0 mm) and small (0.063–0.25 mm) particle fraction, and calculated the corresponding mean retention times (MRTs). For comparison, the same experiment was performed in goats. In goats, as expected, MRTsolute (35 hr) was significantly shorter than MRTparticle (51 hr); only a very small fraction of particle marker was excreted as large particles (2%); and the MRT of these large particles was significantly shorter than that of small particles (with a relevant difference of 8.6 hr), indicating that those few large particles that escape the rumen do so mostly soon after ingestion. In ponies, MRTsolute (24 hr) did not differ from MRTparticle (24 hr); a higher fraction of particle marker was excreted as large particles (5%); and the MRT of these large particles was longer than that of small particles (but with a non-relevant difference of less than 1 hr). These results indicate that no relevant net separation of digesta phases occurs in horses and that selective particle retention mechanisms in the large intestine are unlikely to represent important characteristics of the horse’s digestive physiology.

Abstract

There is a discrepancy in the literature on potential digesta separation mechanisms in horses, with both a selective retention of fine and of large particles postulated in different publications. To assess the net effect of such mechanisms, we fed ponies on a hay-only diet a pulse dose of whole (unchopped) marked hay together with a solute marker, collected faeces on a regular basis, measured marker concentrations in whole faeces and in their large (2.0–16 mm), medium (0.5–1.0 mm) and small (0.063–0.25 mm) particle fraction, and calculated the corresponding mean retention times (MRTs). For comparison, the same experiment was performed in goats. In goats, as expected, MRTsolute (35 hr) was significantly shorter than MRTparticle (51 hr); only a very small fraction of particle marker was excreted as large particles (2%); and the MRT of these large particles was significantly shorter than that of small particles (with a relevant difference of 8.6 hr), indicating that those few large particles that escape the rumen do so mostly soon after ingestion. In ponies, MRTsolute (24 hr) did not differ from MRTparticle (24 hr); a higher fraction of particle marker was excreted as large particles (5%); and the MRT of these large particles was longer than that of small particles (but with a non-relevant difference of less than 1 hr). These results indicate that no relevant net separation of digesta phases occurs in horses and that selective particle retention mechanisms in the large intestine are unlikely to represent important characteristics of the horse’s digestive physiology.

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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
Uncontrolled Keywords:colon, digesta retention, equid, particle size, ruminant
Language:English
Date:2018
Deposited On:04 May 2018 10:32
Last Modified:10 Feb 2020 11:25
Publisher:Wiley-Blackwell Publishing, Inc.
ISSN:0931-2439
OA Status:Closed
Publisher DOI:https://doi.org/10.1111/jpn.12763
PubMed ID:28696048

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