Premium
Comparative selective retention of particle size classes in the gastrointestinal tract of ponies and goats
Author(s) -
Hummel J.,
Scheurich F.,
Ortmann S.,
Crompton L. A.,
Gerken M.,
Clauss M.
Publication year - 2018
Publication title -
journal of animal physiology and animal nutrition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.651
H-Index - 56
eISSN - 1439-0396
pISSN - 0931-2439
DOI - 10.1111/jpn.12763
Subject(s) - gastrointestinal tract , particle size , zoology , biology , veterinary medicine , food science , medicine , biochemistry , paleontology
Summary 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 ( MRT s). For comparison, the same experiment was performed in goats. In goats, as expected, MRT solute (35 hr) was significantly shorter than MRT particle (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 solute (24 hr) did not differ from MRT particle (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.