A dynamic mechanistic model of methanogenesis in the lactating dairy cow

J.A.N. Mills, J. Dijkstra, J. France

Research output: Contribution to journalAbstractAcademic

Abstract

Dietary intervention to reduce methane emissions from lactating dairycattleisbothenvironmentallyandnutritionallydesirableduetotheim-portance of methane as a causative agent in global warming and as asignificant loss of feed energy. This investigation involved the modifica-tion of a dynamic mechanistic model of whole rumen function (Dijkstraet al., 1992) and the incorporation of a postruminal digestive element.Regression analysis showed good agreement between observed and pre-dicted results for experimental data taken from the literature (r20.76,root MSPE 15.4%). Evaluation of model predictions for experimentalobservations from five calorimetry studies with lactating dairy cows atCEDAR (Centre for Dairy Research, UK) showed an under-prediction(2.1MJ/d) of methane production (r20.46, root MSPE 12.4%). Modeldevelopment to account for discontinuous feed inputs and a physical di-etary description may further improve predictions of methanogenesis.Improvements to the representation of lipid metabolism in the rumenare needed to further enhance model predictions especially for dietswith supplemental fat. Application of the model to develop diets tominimise methanogenesis indicates a need to limit the concentration ofsoluble sugars in the concentrate. The model simulated an increase indiet metabolisability (ME/GE) of 3.5% and a 1.1% reduction in theproportion of GE lost as methane as starch replaced soluble sugars intheconcentrate. Onaherdbasis, themodelpredictsthatincreasingdi-etary energy intake per cow can minimisethe annual loss of feed energythrough methane production. Substitution of grass silage with maizesilage or concentrates may significantly reduce the environmental im-pact of dairy farming through methane pollution whilst increasing thedietary energy available to the dairy cow
Original languageEnglish
Pages (from-to)261-261
JournalJournal of Dairy Science
Volume83
Issue numbersuppl. 1
Publication statusPublished - 2000

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