Interaction between milk composition and dairy chain sustainability

Topic 1. Towards a more sustainable dairy production: Monitor, reduction and understanding of methane emission by dairy cows.

Greenhouse gas emission, by dairy cows is of great concern. For the sustainability of dairy production in The Netherlands it is of important to reduce the emission of greenhouse gas, in particular the emission of methane, and thereby reduce the ecological footprint of milk production. The largest part of the methane is produced by the microbiota in the rumen of the cow. In the rumen of a cow, low quality feeds are fermented by microorganisms in an anaerobic environment. The end products of the microbial fermentation are short chain fatty acids (SCFAs), microbial biomass and the gasses carbon dioxide and methane (Krause et al.). The rumen metabolism responsible for the SCFAs in turn is linked to methane formation via the hydrogen potential in the rumen. Depending on the metabolic pathways in the rumen the formation of hydrogen and consequently the generation of methane will differ. Further, the odd numbered fatty acids (C15:0 and C17:0) in milk are indicative of starch- and sugarmetabolizing bacteria whereas branched fatty acids are indicative of cell wall polymer degrading bacteria. Also, SCF are precursors for de novo fatty acid synthesis of milk fatty acids (FA) in the mammary gland. Thus relationships between milk FA and methane formation have been proposed.

Objectives

We aim at a better characterization of the rumen and milk composition (metabolome) in relation to methane emission, by using several cutting edge tecniques such as GC-MS and proton NMR. Several questions can be used in a thesis topic:

• What is the fermentation profile of the rumen thought out the time? And how can this be related to the feeding and/or genetics of the cow?
• What are the most important milk components related to methane emission?
• A previous analysis of the relationship between methane and milk fatty acid profile, has provided clear information on the potential to use fatty acids as an indicator of methane. Is it possible to increase the robustness and reliability of the indicator by using other milk components than fatty acids (e.g. volatile and soluble components)
  

For more information on this topic please contact Elsa Antunes Fernandes.