Merycism in western grey (Macropus fuliginosus) and red kangaroos (Macropus rufus)

Vendl, Catharina; Munn, Adam J.; Leggett, Keith E. A.; Clauss, Marcus

doi:10.1016/j.mambio.2017.03.005

Cited by 7 publications

(4 citation statements)

References 19 publications

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“…This increased chewing efficiency is not achieved by a particular dental design, but by a density-depending sorting mechanism in the forestomach, which separates the small particles from the large ones that are then regurgitated to be masticated again (i.e., rumination) (Lechner-Doll et al, 1991). Although merycism (i.e., regurgitation and re-mastication) and the presence of comparatively fine digesta particles have been reported in non-ruminant foregut fermenters such as kangaroos Vendl et al, 2017) and proboscic monkeys (Nasalis larvatus) (Matsuda et al, 2011;Matsuda et al, 2014), true rumination linked to a sorting mechanism and with a physiologically fixed motor sequence (Gordon, 1968) only evolved twice, in the camelids and the taxonomic ruminants. While there appears to be no functional difference in the forestomach particle sorting mechanism between these two functional ruminant groups (Dittmann et al, 2015b), a major difference between them is the generally lower metabolism and lower feed intake in camelids (Dittmann et al, 2014).…”

Section: Basic Ruminant Digestive Physiologymentioning

confidence: 99%

Physiological adaptations of ruminants and their potential relevance for production systems

Clauss

Hummel

2017

R. Bras. Zootec.

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-Herbivores face the dilemma that the level of feed intake is negatively related to factors that determine digestive efficiency, such as thoroughness of ingesta comminution by chewing, and retention of digesta in the digestive tract. Ruminants have evolved particular adaptations to solve this dilemma. Most ruminants share the characteristic of "digesta washing": fluid moves through their digestive tract faster than particles, thus effectively washing very fine particles, such as bacteria, out of the digesta plug. As the forestomach is followed by auto-enzymatic digestion, this allows a continuous, increased harvest of microbes from the forestomach. True rumination only evolved twice, in the camelids and the true ruminants. These both evolved a density-dependent sorting mechanism based on physical separation of the digesta by the process of flotation and sedimentation, ensuring that the process of rumination is applied to large particles. Differences in this sorting mechanism might facilitate a faster digesta processing in true ruminants as compared with camelids. The hallmark of ruminant digestive anatomy is the omasum, in which the fluid required for both digesta washing and the reticular separation mechanism is re-absorbed. In ruminants of the tribe Bovini, the omasum has reached the largest size and this group has a particularly great forestomach fluid throughput. Increasing the degree of digesta washing even more should increase microbial harvest from the forestomach and reduce the susceptibility to acidosis. At the same time, it should result in a metabolic state of the microbiome more tuned towards biomass production and less towards methanogenesis. Enhancing the forestomach fluid throughput by selective breeding could represent a promising way to further advance the productivity of the ruminant digestive tract.

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Section: Basic Ruminant Digestive Physiologymentioning

confidence: 99%

Physiological adaptations of ruminants and their potential relevance for production systems

Clauss

Hummel

2017

R. Bras. Zootec.

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“…Merycism doubtlessly occurs among mammals with a simple stomach in koalas ( Phascolarctos cinereus ) [93], and in mammals with a complex stomach in macropods (kangaroos) [94] and proboscis monkeys ( Nasalis larvatus ) [90]. While its causes remain obscure in macropods, it was associated with a compensation for tooth wear in koalas [95], with increasing leaf ingestion in proboscis monkeys [96] and generally with periods of higher food intake in koalas [97] and a proboscis monkey [90], in line with the general argument that finer particles can be digested faster and hence will allow higher food intakes.…”

Section: Ruminationmentioning

confidence: 99%

Teeth and the gastrointestinal tract in mammals: when 1 + 1 = 3

Clauss,

Fritz,

Hummel

2023

Phil. Trans. R. Soc. B

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Both teeth and the digestive tract show adaptations that are commonly interpreted in the context of trophic guilds—faunivory, herbivory and omnivory. Teeth prepare food for the digestive tract, and dental evolution focuses on increasing durability and functionality; in particular, size reduction of plant particles is an important preparation for microbial fermentative digestion. In narratives of digestive adaptations, microbes are typically considered as service providers, facilitating digestion. That the majority of ‘herbivorous’ (and possibly ‘omnivorous’) mammals display adaptations to maximize microbes' use as prey—by harvesting the microbes multiplying in their guts—is less emphasized and not reflected in trophic labels. Harvesting of microbes occurs either via coprophagy after separation from indigestible material by a separation mechanism in the hindgut, or from a forestomach by a ‘washing mechanism’ that selectively removes fines, including microbes, to the lower digestive tract. The evolution of this washing mechanism as part of the microbe farming niche opened the opportunity for the evolution of another mechanism that links teeth and guts in an innovative way—the sorting and cleaning of not-yet-sufficiently-size-reduced food that is then re-submitted to repeated mastication (rumination), leading to unprecedented chewing and digestive efficiency. This article is part of the theme issue ‘Food processing and nutritional assimilation in animals’.

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“…When a similar behaviour of regurgitating, re‐masticating and re‐swallowing is observed in non‐ruminant species, it is usually referred to as ‘merycism’, the Greek word for ‘rumination’ (Barker et al ., 1963), or simply as ‘R/R’ (regurgitation and re‐mastication). R/R has been described in a variety of mammalian herbivores (Clauss et al ., 2023), including koalas (Logan, 2001) and kangaroos (Vendl et al ., 2017), and also proboscis monkeys ( Nasalis larvatus ) (Matsuda et al ., 2011a).…”

Section: Introductionmentioning

confidence: 99%

“…When a similar behaviour of regurgitating, remasticating and re-swallowing is observed in non-ruminant species, it is usually referred to as 'merycism', the Greek word for 'rumination' (Barker et al, 1963), or simply as 'R/R' (regurgitation and re-mastication). R/R has been described in a variety of mammalian herbivores (Clauss et al, 2023), including koalas (Logan, 2001) and kangaroos (Vendl et al, 2017), and also proboscis monkeys (Nasalis larvatus) (Matsuda et al, 2011a). This first description of R/R in proboscis monkeys was based on direct and video observation of free-ranging individuals in Malaysia during daylight hours, and although it was described for 23 different individuals, its occurrence was sporadic (Matsuda et al, 2011a).…”

Section: Introductionmentioning

confidence: 99%

They chew by night? Night‐time behaviour in a ‘ruminating’ primate, the proboscis monkey (Nasalis larvatus)

Bösch,

McGrosky,

Tuuga

et al. 2023

Journal of Zoology

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Studies of diurnal primates have long considered the nocturnal period to be a time spent merely sleeping and not effectively utilized for foraging or social behaviours. However, digestive activity should continue during the night. To explore the adaptive significance of the primate rumination‐like behaviour, that is, regurgitation and re‐mastication (R/R), observed in the proboscis monkey Nasalis larvatus (but only infrequently during the day), we tested the hypothesis that they frequently awaken and ‘ruminate’ at night through detailed nocturnal observations. We analysed infrared video recordings of nocturnal behaviours of 179 individuals over 35 nights, totalling over 251 h, of free‐ranging proboscis monkeys in the lower Kinabatangan region of Sabah, Malaysian Borneo. The results showed that, as we expected, proboscis monkeys were frequently awake at night; they only slept about one third of the time observed at night (27.4 ± 24.6%), with juveniles sleeping the most and subadults sleeping the least. However, contrary to our expectations, R/R did not appear to occur more frequently than during daytime observations and accounted for a minor proportion of the total activity budget during the night. Whether frequent waking up during the night represents an adaptive strategy in relation to predation avoidance, or is a consequence of disturbance (e.g. due to moving branches or mosquitoes), requires further study, ideally in comparison with protected ex situ conditions. Our findings suggest that without detailed observations, primate sleeping times may easily be overestimated due to a high proportion of time spent awake but resting.

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Merycism in western grey (Macropus fuliginosus) and red kangaroos (Macropus rufus)

Cited by 7 publications

References 19 publications

Physiological adaptations of ruminants and their potential relevance for production systems

Physiological adaptations of ruminants and their potential relevance for production systems

Teeth and the gastrointestinal tract in mammals: when 1 + 1 = 3

They chew by night? Night‐time behaviour in a ‘ruminating’ primate, the proboscis monkey (Nasalis larvatus)

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