Comparative selective retention of particle size classes in the gastrointestinal tract of ponies and goats.
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, MRT (35 hr) was significantly shorter than MRT (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, MRT (24 hr) did not differ from MRT (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.
© 2017 Blackwell Verlag GmbH.
Publication Date: 2017-07-11 PubMed ID: 28696048DOI: 10.1111/jpn.12763Google Scholar: Lookup
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- Journal Article
Summary
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The research works on resolving disagreements in existing literature over the digestive processes in horses. It does this by examining how different sizes of ingested particles are retained and processed in the gastrointestinal tracts of ponies and goats.
Research Methodology
- The researchers focused on the digestive patterns of ponies and goats, with the aim of understanding separation mechanisms in horses.
- Ponies were fed on a hay-only diet with a pulse dose of whole, marked hay and a solute marker. Faeces were later collected regularly for analysis.
- The faeces were analyzed for marker concentrations in the whole and in large, medium, and small particle sizes to calculate their corresponding mean retention times (MRT).
- For a comparative study, the same experiment was performed with goats.
Findings and Interpretations
- In goats, the MRT was observed to be significantly longer (35 hours) than in ponies (24 hours). Further, only 2% of the particle marker was excreted as large particles and these large particles were excreted sooner than smaller ones (about 8.6 hours sooner).
- In ponies, the MRT did not differ based on particle size, and 5% of the ingested particle marker was excreted as large particles. The difference in MRT between large and small particles was not significant (less than 1 hour).
- Thus, the study indicated a lack of significant net separation of digesta phases in horses. Moreover, the authors concluded that selective particle retention in the large intestine may not be an important characteristic of a horse’s digestive physiology.
Conclusion and Importance
- This research is significant in that it helps to clarify our understanding of the digestive physiology of horses, specifically regarding particle retention and separation in their gastrointestinal tract.
- The outcomes provide substantial evidence against the prevalent theory of selective particle retention in the large intestine of horses.
Cite This Article
APA
Hummel J, Scheurich F, Ortmann S, Crompton LA, Gerken M, Clauss M.
(2017).
Comparative selective retention of particle size classes in the gastrointestinal tract of ponies and goats.
J Anim Physiol Anim Nutr (Berl), 102(2), 429-439.
https://doi.org/10.1111/jpn.12763 Publication
Researcher Affiliations
- Department of Animal Sciences, University of Göttingen, Göttingen, Germany.
- Department of Animal Sciences, University of Göttingen, Göttingen, Germany.
- Leibniz Institute for Zoo and Wildlife Research (IZW), Berlin, Germany.
- Sustainable Agriculture and Food Systems Research Division, Centre for Dairy Research, School of Agriculture, Policy and Development, University of Reading, Reading, UK.
- Department of Animal Sciences, University of Göttingen, Göttingen, Germany.
- Clinic for Zoo Animals, Exotic Pets and Wildlife, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland.
MeSH Terms
- Animal Feed / analysis
- Animal Nutritional Physiological Phenomena
- Animals
- Diet / veterinary
- Female
- Gastrointestinal Tract / anatomy & histology
- Goats / physiology
- Horses / physiology
- Particle Size
- Species Specificity
Citations
This article has been cited 8 times.- Schwarm A, Clauss M, Ortmann S, Jensen RB. No size-dependent net particle retention in the hindgut of horses. J Anim Physiol Anim Nutr (Berl) 2022 Nov;106(6):1356-1363.
- Raspa F, Vervuert I, Capucchio MT, Colombino E, Bergero D, Forte C, Greppi M, Cavallarin L, Giribaldi M, Antoniazzi S, Cavallini D, Valvassori E, Valle E. A high-starch vs. high-fibre diet: effects on the gut environment of the different intestinal compartments of the horse digestive tract. BMC Vet Res 2022 May 19;18(1):187.
- Findeisen E, Südekum KH, Fritz J, Hummel J, Clauss M. Increasing food intake affects digesta retention, digestibility and gut fill but not chewing efficiency in domestic rabbits (Oryctolagus cuniculus). J Exp Zool A Ecol Integr Physiol 2021 Aug;335(7):614-622.
- Vinzelj J, Nash K, Jones AL, Young RT, Meili CH, Pratt CJ, Wang Y, Elshahed MS, Youssef NH. Anaerobic gut fungal community in ostriches (Struthio camelus). ISME Commun 2025 Jan;5(1):ycaf144.
- Abraham AJ, Duvall ES, Doughty CE, Riond B, Ortmann S, Terranova M, le Roux E, Clauss M. Sodium Retention in Large Herbivores: Physiological Insights and Zoogeochemical Consequences. J Exp Zool A Ecol Integr Physiol 2025 Jul;343(6):664-676.
- Vinzelj J, Nash K, Jones AL, Young RT, Meili CH, Pratt CJ, Wang Y, Elshahed MS, Youssef NH. The anaerobic gut fungal community in ostriches (Struthio camelus). bioRxiv 2025 Mar 30;.
- Lopes DS, Rodrigues MT, de Oliveira TS. Effects of forage quality and particle size on feed intake and ruminoreticulum content of goats. Transl Anim Sci 2023;7(1):txad101.
- Clauss M, Fritz J, Hummel J. Teeth and the gastrointestinal tract in mammals: when 1 + 1 = 3. Philos Trans R Soc Lond B Biol Sci 2023 Dec 4;378(1891):20220544.
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