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  • Decreasing methane yield with increasing food intake keeps daily methane emissions constant in two foregut fermenting marsupials, the western grey kangaroo and red kangaroo.

Decreasing methane yield with increasing food intake keeps daily methane emissions constant in two foregut fermenting marsupials, the western grey kangaroo and red kangaroo.

The Journal of experimental biology (2015-11-06)
Catharina Vendl, Marcus Clauss, Mathew Stewart, Keith Leggett, Jürgen Hummel, Michael Kreuzer, Adam Munn
ABSTRACT

Fundamental differences in methane (CH4) production between macropods (kangaroos) and ruminants have been suggested and linked to differences in the composition of the forestomach microbiome. Using six western grey kangaroos (Macropus fuliginosus) and four red kangaroos (Macropus rufus), we measured daily absolute CH4 production in vivo as well as CH4 yield (CH4 per unit of intake of dry matter, gross energy or digestible fibre) by open-circuit respirometry. Two food intake levels were tested using a chopped lucerne hay (alfalfa) diet. Body mass-specific absolute CH4 production resembled values previously reported in wallabies and non-ruminant herbivores such as horses, and did not differ with food intake level, although there was no concomitant proportionate decrease in fibre digestibility with higher food intake. In contrast, CH4 yield decreased with increasing intake, and was intermediate between values reported for ruminants and non-ruminant herbivores. These results correspond to those in ruminants and other non-ruminant species where increased intake (and hence a shorter digesta retention in the gut) leads to a lower CH4 yield. We hypothesize that rather than harbouring a fundamentally different microbiome in their foregut, the microbiome of macropods is in a particular metabolic state more tuned towards growth (i.e. biomass production) rather than CH4 production. This is due to the short digesta retention time in macropods and the known distinct 'digesta washing' in the gut of macropods, where fluids move faster than particles and hence most likely wash out microbes from the forestomach. Although our data suggest that kangaroos only produce about 27% of the body mass-specific volume of CH4 of ruminants, it remains to be modelled with species-specific growth rates and production conditions whether or not significantly lower CH4 amounts are emitted per kg of meat in kangaroo than in beef or mutton production.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
Methane-12C, 13C-depleted, 99.9 atom % 12C
Sigma-Aldrich
Carbon nanofibers, graphitized, platelets(conical), >98% carbon basis, D × L 100 nm × 20-200 μm
Sigma-Aldrich
Carbon nanofibers, pyrolitically stripped, platelets(conical), >98% carbon basis, D × L 100 nm × 20-200 μm
Sigma-Aldrich
Diazepam
Supelco
Diazepam solution, 1.0 mg/mL in methanol, ampule of 1 mL, certified reference material, Cerilliant®
Carbon - Vitreous, rod, 50mm, diameter 1.0mm, glassy carbon
Carbon - Vitreous, rod, 100mm, diameter 5.0mm, glassy carbon
Carbon - Vitreous, foil, 100x100mm, thickness 6.0mm, glassy carbon
Carbon - Vitreous, foil, 10x10mm, thickness 4.0mm, glassy carbon
Carbon - Vitreous, rod, 100mm, diameter 1.0mm, glassy carbon
Carbon - Vitreous, rod, 5mm, diameter 3.0mm, glassy carbon
Carbon - Vitreous, foil, 25x25mm, thickness 0.5mm, glassy carbon
Carbon - Vitreous, rod, 100mm, diameter 3.0mm, glassy carbon
Carbon - Vitreous, tube, 100mm, outside diameter 10mm, inside diameter 3mm, wall thickness 3.5mm, glassy carbon
Carbon - Vitreous, rod, 200mm, diameter 10mm, glassy carbon
Carbon - Vitreous, foam, 150x150mm, thickness 2.5mm, bulk density 0.05g/cm3, porosity 96.5%
Carbon - Vitreous, foam, 150x150mm, 0.05g.cmué, porosity 96.5%, 24 pores/cm
Carbon - Vitreous, tube, 50mm, outside diameter 10mm, inside diameter 3mm, wall thickness 3.5mm, glassy carbon
Carbon - Vitreous, foam, 300x300mm, thickness 20mm, bulk density 0.05g/cm3, porosity 96.5%
Carbon - Vitreous, rod, 100mm, diameter 7.0mm, glassy carbon
Carbon - Vitreous, foil, 100x100mm, thickness 1.0mm, glassy carbon
Carbon - Vitreous, foil, 25x25mm, thickness 4.0mm, glassy carbon
Carbon - Vitreous, foil, 100x100mm, thickness 2.0mm, glassy carbon
Carbon - Vitreous, foil, 50x50mm, thickness 4.0mm, glassy carbon
Carbon - Vitreous, rod, 200mm, diameter 1.0mm, glassy carbon
Carbon - Vitreous, foam, 150x150mm, thickness 3.2mm, bulk density 0.05g/cm3, porosity 96.5%
Carbon - Vitreous, foam, 300x300mm, thickness 30mm, bulk density 0.05g/cm3, porosity 96.5%
Carbon - Vitreous, rod, 200mm, diameter 5.0mm, glassy carbon
Carbon - Vitreous, foil, 50x50mm, thickness 1.0mm, glassy carbon
Carbon - Vitreous, rod, 200mm, diameter 3.0mm, glassy carbon