| Title: | Milk metabolome relates enteric methane emission to milk synthesis and energy metabolism pathways |
| Author(s): | Antunes-Fernandes EC; van Gastelen S; Dijkstra J; Hettinga KA; Vervoort J; |
| Address: | "Top Institute Food and Nutrition, PO Box 557, 6700 AN Wageningen, the Netherlands; Food Quality and Design Group, Wageningen University, PO Box 17, 6700 AH Wageningen, the Netherlands. Top Institute Food and Nutrition, PO Box 557, 6700 AN Wageningen, the Netherlands; Animal Nutrition Group, Wageningen University, PO Box 338, 6700 AH Wageningen, the Netherlands. Animal Nutrition Group, Wageningen University, PO Box 338, 6700 AH Wageningen, the Netherlands. Food Quality and Design Group, Wageningen University, PO Box 17, 6700 AH Wageningen, the Netherlands. Electronic address: kasper.hettinga@wur.nl. Laboratory of Biochemistry, Wageningen University, Dreijenlaan 3, 6703 HA, Wageningen, the Netherlands" |
| ISSN/ISBN: | 1525-3198 (Electronic) 0022-0302 (Linking) |
| Abstract: | "Methane (CH4) emission of dairy cows contributes significantly to the carbon footprint of the dairy chain; therefore, a better understanding of CH4 formation is urgently needed. The present study explored the milk metabolome by gas chromatography-mass spectrometry (milk volatile metabolites) and nuclear magnetic resonance (milk nonvolatile metabolites) to better understand the biological pathways involved in CH4 emission in dairy cattle. Data were used from a randomized block design experiment with 32 multiparous Holstein-Friesian cows and 4 diets. All diets had a roughage:concentrate ratio of 80:20 (dry matter basis) and the roughage was grass silage (GS), corn silage (CS), or a mixture of both (67% GS, 33% CS; 33% GS, 67% CS). Methane emission was measured in climate respiration chambers and expressed as CH4 yield (per unit of dry matter intake) and CH4 intensity (per unit of fat- and protein-corrected milk; FPCM). No volatile or nonvolatile metabolite was positively related to CH4 yield, and acetone (measured as a volatile and as a nonvolatile metabolite) was negatively related to CH4 yield. The volatile metabolites 1-heptanol-decanol, 3-nonanone, ethanol, and tetrahydrofuran were positively related to CH4 intensity. None of the volatile metabolites was negatively related to CH4 intensity. The nonvolatile metabolites acetoacetate, creatinine, ethanol, formate, methylmalonate, and N-acetylsugar A were positively related to CH4 intensity, and uridine diphosphate (UDP)-hexose B and citrate were negatively related to CH4 intensity. Several volatile and nonvolatile metabolites that were correlated with CH4 intensity also were correlated with FPCM and not significantly related to CH4 intensity anymore when FPCM was included as covariate. This suggests that changes in these milk metabolites may be related to changes in milk yield or metabolic processes involved in milk synthesis. The UDP-hexose B was correlated with FPCM, whereas citrate was not. Both metabolites were still related to CH4 intensity when FPCM was included as covariate. The UDP-hexose B is an intermediate of lactose metabolism, and citrate is an important intermediate of Krebs cycle-related energy processes. Therefore, the negative correlation of UDP-hexose B and citrate with CH4 intensity may reflect a decrease in metabolic activity in the mammary gland. Our results suggest that an integrative approach including milk yield and composition, and dietary and animal traits will help to explain the biological metabolism of dairy cows in relation to methane CH4 emission" |
| Keywords: | Acetone/analysis Animals Body Weight Cattle Diet/veterinary *Energy Metabolism Female Lactation Lactose/metabolism Linear Models *Metabolome Methane/*biosynthesis Milk/*chemistry/*metabolism Milk Proteins/metabolism Poaceae Silage/analysis Volatile Organi; |
| Notes: | "MedlineAntunes-Fernandes, E C van Gastelen, S Dijkstra, J Hettinga, K A Vervoort, J eng Randomized Controlled Trial 2016/05/30 J Dairy Sci. 2016 Aug; 99(8):6251-6262. doi: 10.3168/jds.2015-10248. Epub 2016 May 26" |
