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Mechanistic modelling of enteric methane production: a thesis presented in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Mathematics at Massey University, Manawatu Campus, New Zealand

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posted on 2023-05-03, 14:10 authored by James Wang
Globally, 14.5% of all anthropogenic greenhouse gases come from ruminants. One of these is methane, which is produced in the rumen of ruminant animals. Feed is degraded by microbes to produce volatile fatty acids (which are absorbed by the animal) and hydrogen (which is metabolized by methanogens to form methane). The dynamics of hydrogen production and metabolism are subject to thermodynamic control imposed by the hydrogen concentration. Existing models to estimate methane production are based on calculation of hydrogen balances without considering the presence of methanogens and do not include thermodynamic control. In this project, a model is developed based on glucose-hydrogenmethanogen dynamics to estimate methane production and illustrates a co-existence of microbes that employs different fermentation pathways competing for the same food source in the rumen. Glucose was chosen as an example of a fermentable feed component. A thermodynamic term was integrated into a Monod-type model to represent the thermodynamic control of hydrogen concentration on the rates of hydrogen generation and hydrogen metabolism. Results of this model suggest that the microbial community composition and the combination of the different pathways are determined by the rumen environment, biological parameters of the microbes and the feedback imposed by substrate and product concentrations. The mathematical enunciation of this model is therefore consistent with biological expectations. This model could be expanded to include plant polymer degradation rate, feeding level and feeding frequency to explore their effects on methane production. This model could also be integrated into models of whole rumen function to address more complex questions. It would also support experimentation with animals for understanding factors that control methane formation and to explore methane mitigation strategies.

History

Rights statement

The Author

Language

  • English

Does this contain Māori information or data?

  • No

Publisher

Massey University

Citation

Wang, Y. (2016). Mechanistic modelling of enteric methane production: a thesis presented in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Mathematics at Massey University, Manawatu Campus, New Zealand.

Funder

Pastoral Greenhouse Gas Research Consortium (PGgRc)||New Zealand Agricultural Greenhouse Gas Research Centre

Contract number

A20535

Job code

12551x10

Degree name

Doctor of Philosophy

Institution name

Massey University

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