Retention of different-sized particles and derived gut fill estimate in tammar wallabies (Macropus eugenii): Physiological and methodological considerations

Munn, Adam J.; Tomlinson, Susie; Savage, Trevor N.; Clauss, Marcus

doi:10.1016/j.cbpa.2011.11.003

Cited by 19 publications

(10 citation statements)

References 40 publications

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“…The results for ponies are in line with those for other large, nonruminant foregut fermenters including macropods, peccaries, hippos and colobine monkeys, in which no selective retention of a certain particle size fraction was observed (Matsuda et al, 2015;Munn, Tomlinson, Savage, & Clauss, 2012;Schwarm, Ortmann, Wolf, Streich, & Clauss, 2009;Schwarm et al, 2008). Anyhow, a selective retention of large particles in a non-ruminant herbivore appears unlikely.…”

Section: Discussionsupporting

confidence: 82%

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

Hummel

Scheurich

Ortmann

et al. 2017

Animal Physiology Nutrition

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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.

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Section: Discussionsupporting

confidence: 82%

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

Hummel

Scheurich

Ortmann

et al. 2017

Animal Physiology Nutrition

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“…At any particular distance from the sacculated forestomach in the tubiform organ (or haustral pouch), biofilm consortia can be expected to be at the same stage of development, growth, maturation and detachment. This expectation is reinforced by the fact that differently sized particles travel at the same rate during digesta passage through the forestomach of macropods (Munn et al 2012).…”

Section: Factors Affecting the Nature And Microbial Composition Of Bimentioning

confidence: 99%

Unravelling methanogenesis in ruminants, horses and kangaroos: the links between gut anatomy, microbial biofilms and host immunity

Leng¹

2018

Anim. Prod. Sci.

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The present essay aims to resolve the question as to why macropod marsupials (e.g. kangaroos and wallabies, hereinafter termed 'macropods) and horses produce much less methane (CH 4 ) than do ruminants when digesting the same feed. In herbivores, gases produced during fermentation of fibrous feeds do not pose a major problem in regions of the gut that have mechanisms to eliminate them (e.g. eructation in the rumen and flatus in the lower bowel). In contrast, gas pressure build-up in the tubiform forestomach of macropods or in the enlarged tubiform caecum of equids would be potentially damaging. It is hypothesised that, to prevent this problem, evolution has favoured development of controls over gut microbiota that enable enteric gas production (H 2 and CH 4 ) to be differently regulated in the forestomach of macropods and the caecum of all three species, from the forestomach of ruminants. The hypothesised regulation depends on interactions between their gut anatomy and host-tissue immune responses that have evolved to modify the species composition of their gut microbiota which, importantly, are mainly in biofilms. Obligatory H 2 production during forage fermentation is, thus, captured in CH 4 in the ruminant where ruminal gases are readily released by eructation, or in acetate in the macropod forestomach and equid caecum-colon where a build-up in gas pressure could potentially damage these organs. So as to maintain appropriate gut microbiota in different species, it is hypothesised that blind sacs at the cranial end of the haustral anatomy of the macropod forestomach and the equid caecum are sites of release of protobiofilm particles that develop in close association with the mucosal lymphoid tissues. These tissues release immune secretions such as antimicrobial peptides, immunoglobulins, innate lymphoid cells and mucin that eliminate or suppress methanogenic Archaea and support the growth of acetogenic microbiota. The present review draws on microbiological studies of the mammalian gut as well as other microbial environments. Hypotheses are advanced to account for published findings relating to the gut anatomy of herbivores and humans, the kinetics of digesta in ruminants, macropods and equids, and also the composition of biofilm microbiota in the human gut as well as aquatic and other environments where the microbiota exist in biofilms.

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“…Holleman and White (1989) and Munn et al (2012) showed that assuming 175 a linear course of digestion across MRT yields better results when validated against empirical 176 measures in slaughtered animals, albeit using small sample sizes. Because assuming a linear 177 course of digestion across MRT means that dDMC is assumed to be present in the GIT during 178 half of MRT, it follows that 179 dDMC [kg] = DMI [kg/h] * aD DM * (MRT particle GIT [h] / 2) (6).…”

Section: Introduction 59mentioning

confidence: 99%

“…If in addition to measures of food 210 intake and digesta retention, the apparent digestibility of dry matter is also measured in the 211 same feeding trial, the derivation of indigestible and complete gut fill (as DMC) as indicated 212 in the equations above is possible. Although this has been done repeatedly in individual 213 studies to compare selected species, or make intraspecific or inter-clade comparisons (Baker 214 and Hobbs, 1987;Gross et al, 1996;Behrend et al, 2004;Munn 215 and Barboza, 2008;Clauss et al, 2010b;Franz et al, 2011b;Sawada 216 et al, 2011;Fritz et al, 2012;Munn et al, 2012), a large-scale comparison of mammalian 217 herbivore gut fill has not been performed so far. Therefore, it is the aim of this study to 218 explore the scaling of food intake, digesta retention, apparent digestibility and the calculated 219 gut fill in mammalian herbivores, using available literature data.…”

mentioning

confidence: 99%

Assessing the Jarman–Bell Principle: Scaling of intake, digestibility, retention time and gut fill with body mass in mammalian herbivores

Müller

Codron

Meloro

et al. 2013

Comparative Biochemistry and Physiology Part A: Molecular &

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177

158

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Differences in allometric scaling of physiological characters have the appeal to explain species diversification and niche differentiation along a body mass (BM) gradient -because they lead to different combinations of physiological properties, and thus may facilitate different adaptive strategies. An important argument in physiological ecology is built on the allometries of gut fill (assumed to scale to BM1.0) and energy requirements/intake (assumed to scale to BM0.75) in mammalian herbivores. From the difference in exponents, it has been postulated that the mean retention time (MRT) of digesta should scale to BM1.0-0.75 = BM0.25. This has been used to argue that larger animals have an advantage in digestive efficiency and hence can tolerate lower-quality diets. However, empirical data does not support the BM0.25 scaling of MRT, and the deduction of MRT scaling implies, according to physical principles, no scaling of digestibility; basing assumptions on digestive efficiency on the thus-derived MRT scaling amounts to circular reasoning. An alternative explanation considers a higher scaling exponent for food intake than for metabolism, allowing larger animals to eat more of a lower quality food without having to increase digestive efficiency; to date, this concept has only been explored in ruminants. Here, using data for 77 species in which intake, digestibility and MRT were measured (allowing the calculation of the dry matter gut contents DMC), we show that the unexpected shallow scaling of MRT is common in herbivores and may result from deviations of other scaling exponents from expectations. Notably, DMC have a lower scaling exponent than 1.0, and the 95% confidence intervals of the scaling exponents for intake and DMC generally overlap. Differences in the scaling of wet gut contents and dry matter gut contents confirm a previous finding that the dry matter concentration of gut contents decreases with body mass, possibly compensating for the less favourable volume-surface ratio in the guts of larger organisms. These findings suggest that traditional explanations for herbivore niche differentiation along a BM gradient should not be based on allometries of digestive physiology. In contrast, they support the recent interpretation that larger species can tolerate lower-quality diets because their intake has a higher allometric scaling than their basal metabolism, allowing them to eat relatively more of a lower quality food without having to increase digestive efficiency. MRT scaling amounts to circular reasoning. An alternative explanation considers a higher 38 scaling exponent for food intake than for metabolism, allowing larger animals to eat more of a 39 lower quality food without having to increase digestive efficiency; to date, this concept has 40 only been explored in ruminants. Here, using data for 77 species in which intake, digestibility 41 and MRT were measured (allowing the calculation of the dry matter gut contents DMC), we 42show that the unexpected shallow scaling of MRT is common in herbi...

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Retention of different-sized particles and derived gut fill estimate in tammar wallabies (Macropus eugenii): Physiological and methodological considerations

Cited by 19 publications

References 40 publications

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

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

Unravelling methanogenesis in ruminants, horses and kangaroos: the links between gut anatomy, microbial biofilms and host immunity

Assessing the Jarman–Bell Principle: Scaling of intake, digestibility, retention time and gut fill with body mass in mammalian herbivores

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