Metabolomics analysis reveals large effect of roughage types on rumen microbial metabolic profile in dairy cows

The aim of our study was to determine the effect of diets with different types of roughage on the ruminal microbial metabolite profile in dairy cows. Holstein dairy cows were fed a diet containing either corn stover (CS group) or a mixture of alfalfa hay, Leymus chinensis hay and corn silage (MF group) at 0700 and 1900h daily. Rumen fluid was sampled from each cow through a ruminal cannula at 0630 and 1030h, and the mixed ruminal fluid from 3day in each cow was analysed using nuclear magnetic resonance (NMR) spectroscopy. A multivariate analysis revealed a significant difference between the ruminal metabolome of the CS and MF groups at both time points. The MF group had higher levels of acetate, valerate, hydrocinnamate and methylamine and lower levels of glucose, glycine, propionate and isovalerate than those in the CS group. Our results showed that different types of roughages can significantly influence the ruminal microbial metabolome, especially with regard to organic acids, amines and amino acids.