MollyRum14 Testing Forage_19Oct2017_resub.pdf (907.04 kB)

Evaluation of a sheep rumen model with fresh forages of diverse chemical composition

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journal contribution
posted on 2023-05-03, 09:11 authored by Kumar Vetharaniam, Ronaldo VibartRonaldo Vibart, David PachecoDavid Pacheco
The sheep rumen sub-model MollyRum14 (Vetharaniam et al. 2015; J Anim Sci 10.2527/jas.2015-9037) was evaluated on its methane and VFA predictions against data from respiration-chamber trials conducted with sheep fed perennial ryegrass, white clover, chicory, forage rape, turnip (leafy and bulb varieties), swede, kale or forage radish. We assessed the model’s sensitivity to substrate degradation rate (settings that affect the rate of cellulose and hemicellulose digestion) and to fermentation stoichiometry (settings that alter non-glucogenic to glucogenic volatile fatty acids ratios). Model predictions were evaluated against data for methane production (pCH4: g/d), methane yield (yCH4: g/kg DMI), and acetate to propionate ratio (A:P). The predictive ability of the model for both pCH4 and yCH4 was superior for perennial ryegrass than for other forages. Except for swede and chicory, predictions for yCH4 were correctly ranked across the forages evaluated. Except for forage rape and swedes, robust predictions were obtained for all forages using fast degradation kinetics and a predominantly acetogenic stoichiometry. Model predictions for forage rape and swedes were enhanced using slow degradation kinetics and a predominantly propionic stoichiometry. These results indicate that MollyRum14 is suitable to predict methane emissions from sheep fed a variety of fresh forages including annual fodder crops. However, a clear understanding of degradation rates and stoichiometries is needed to enhance the utility of the model as a predictive tool. This would allow continuous adjustment of digestion rates and stoichiometries, to be potentially tailored to individual forage species.


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© The Author(s) 2018. Published by Oxford University Press on behalf of the American Society of Animal Science. All rights reserved.


  • English

Does this contain Māori information or data?

  • No


Oxford University Press

Journal title

Journal of Animal Science




Vetharaniam, K., Vibart, R. E., & Pacheco, D. (2018). Evaluation of a sheep rumen model with fresh forages of diverse chemical composition. Journal of Animal Science, 96(12), 5287–5299. doi:10.1093/jas/sky354

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