Digesta passage in nondomestic ruminants: separation mechanisms in ‘moose-type’ and ‘cattle-type’ species, and seemingly atypical browsers

• Main Authors: Przybyło, Marcin, Hummel, Jürgen, Ortmann, Sylvia, Codron, Daryl, Kohlschein, Gina-Marie, Kilga, Daniela, Smithyman, Juliet, Przybyło, Urszula, Świerk, Samanta, Hammer, Sven, Hatt, Jean-Michel, Górka, Paweł, Clauss, Marcus
• Format: Article in Journal/Newspaper
• Language: English
• Published: Elsevier 2019
• Subjects: Department of Small Animals; 570 Life sciences; biology; 630 Agriculture; Biochemistry; Physiology; Molecular Biology; Browser; Grazer; Retention; Secondary plant compounds; ‘Cattle-type’; ‘Moose-type’; Alces alces
• Online Access: https://www.zora.uzh.ch/id/eprint/171441/; https://www.zora.uzh.ch/id/eprint/171441/1/CBPA_cattle_type_rules_2019.pdf; https://doi.org/10.1016/j.cbpa.2019.06.010

Ruminants have been classified as having a ‘moose-type’ or ‘cattle-type’ digestive physiology. ‘Cattle-type’ ruminants have a clear difference in the mean retention time (MRT) of fluid vs. small particles in the reticulorumen (RR), with a high ‘selectivity factor’ (SF=MRTparticle/ MRTfluid,>1.80), and are typically grazers and intermediate feeders. ‘Moose-type’ ruminants have lower SF (< 1.80), possibly because of defensive salivary proteins that constrain amounts of (high-viscosity) saliva, and are typically restricted to browsing. To further contribute to testing this physiology-diet correlation, we performed 55 individual passage measurements in 4/6 species that have/have not been investigated previously, respectively. Co-EDTA was used as a solute (fluid) and Cr-mordanted hay particles (< 2 mm) as particle markers. Results are related to the percentage of grass in the natural diet taken from the literature. Moose (Alces alces, n=4 on 4 to 5 diets each and n=2 on a single diet, 5% grass, SF 1.46 ± 0.22) and giraffe (Giraffa camelopardalis, n=3 on 3 to 5 diets each, 1%, 1.42 ± 0.23) as classical ‘moose-type’, and cattle (Bos taurus, n=2, 70%, 2.04) as classical ‘cattle-type’ ruminants yielded results similar to those previously published, as did waterbuck (Kobus ellipsiprymnus, n=5, 84%, 2.46 ± 0.49), corroborating that the SF represents, to a large extent, a species-specific characteristic. Results in oryx (Oryx leucoryx, n=1, 75%, 2.60) and sitatunga (Tragelaphus spekii, n=4, 68%, 1.81 ± 0.21) correspond to the concept of ‘cattletype’ ruminants being grazers or intermediate feeders. However, European bison (Bison bonasus, n=1, 10%, 2.74), nyala (T. angasii, n=6, 20%, 1.95 ± 0.25), bongo (T. eurycerus, n=3, 13%, 2.39 ± 0.54) and gerenuk (Litocranius walleri, n=1, 0%, 2.25) appear as ‘cattle-type’ ruminants, yet have a browse-dominated diet. While the results do not challenge the view that a ‘moose-type’ digestive physiology is an adaptation to browse diets, they indicate that it may not be the only ...