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06/17/2019 10:49

Rinsing System in Stomach Protects the Teeth of Ruminants

Melanie Nyfeler Kommunikation
Universität Zürich

    When they graze, goats, sheep and cows often ingest bits of earth that can be damaging to their teeth. Researchers from the University of Zurich have now shown how the animals protect themselves against dental abrasion: Their stomach system rinses dust and sand off the ingested food before it is chewed for the second time.

    "Field-grazing animals always eat some earth and dust along with the plants," says Jean-Michel Hatt, professor at the Clinic for Zoo Animals, Exotic Pets and Wildlife. This is particularly the case in dry regions where the wind blows a lot of dust around, and causes a lot of work for the mastica-tory organs. His research team has now shown that various mechanisms prevent excessive abra-sion of the teeth - thus ensuring the animals' survival.

    Short and long teeth in the same habitat

    Horses and zebras, for instance, have developed very long teeth in order to compensate for the abrasion caused by dust and sand. Cows and wildebeest, on the other hand, have shorter teeth. "We have always wondered how ruminants living in the same habitat manage with shorter teeth," Hatt explains.

    Ruminants have a stomach system with multiple chambers - rumen, reticuum, omasum and abo-masum - which use bacteria to digest the plant material they eat. The food is washed by rumen fluid and sorted into material that is already small enough to digest, and larger pieces that are regurgitated to be chewed again. It has long been assumed that the cud to be ruminated has been freed from dust and sand.

    Sand collects in the stomach

    Jean-Michel Hatt and his team have now for the first time tested the influence of various types of food on dental abrasion. Using computer tomography, the researchers observed in goats that the sand ingested with the plants was not equally distributed around the gastrointestinal tract, but collected at specific locations. "We were able to show that there was considerably less sand in the upper rumen, where the material to be ruminated is regurgitated, than in the ingested food itself," Hatt explains.

    What happens to the sand? First it sinks down in the rumen and collects in the abomasum, pass-es through the bowel and is then expelled with the undigested material in the feces. "Organisms that develop such a washing system have a natural way to easily get rid of the rinsed-off material," says Hatt. It is only when animals ingest a large amount of sand all at once - for example through badly produced silage with an unusual amount of soil contamination - that complications can occur.

    Ruminants' success model

    For Hatt, the finding provides another piece of the puzzle explaining the evolutionary success of the ruminant model. It also explains why the animals do a much less thorough job of chewing their food into small pieces the first time around than they do later, when they are ruminating clean material.


    Contact for scientific information:

    Prof. Dr. Jean-Michel Hatt
    Clinic for Zoo Animals, Exotic Pets and Wildlife
    Vetsuisse Faculty
    University of Zurich
    Phone: 41 44 635 83 42
    E-mail: jmhatt@vetclinics.uzh.ch


    Original publication:

    Literature:
    Hatt J-M, Codron D, Müller DWH, Ackermans NL, Martin LF, Kircher PR, Hummel J, Clauss M (2019) The rumen washes off abrasives before heavy-duty chewing in ruminants. Mammalian Biology, June 12, 2019. doi 10.1016/j.mambio.2019.06.001


    More information:

    https://www.media.uzh.ch/en/Press-Releases/2019/Rinsing-System-in-Stomach-.html


    Images

    Sand sinks down in the rumen and collects in the abomasum, passes through the bowel and is then expelled with the undigested material in the feces.
    Sand sinks down in the rumen and collects in the abomasum, passes through the bowel and is then expe ...
    (Illustration: UZH)
    None


    Criteria of this press release:
    Journalists
    Biology, Nutrition / healthcare / nursing, Zoology / agricultural and forest sciences
    transregional, national
    Research projects, Research results
    English


     

    Sand sinks down in the rumen and collects in the abomasum, passes through the bowel and is then expelled with the undigested material in the feces.


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