Connecting plant, animal, and human health using untargeted metabolomics.

Abstract

Consumers of meat and milk products are interested in the connection between agricultural practices and the wellbeing of livestock. Consumers are also concerned about the impact of livestock products on their own health and wellbeing, with some turning to alternative plant-based protein sources. The connection between agricultural practice and consumer metabolism has previously been tenuous, but the development of untargeted metabolomic processes offers the opportunity to reconcile and connect opposing spectrums of the food-chain. We performed a cattle grazing study which compared the performance and metabolomic profiles of beef finished on three forage mixtures of either perennial ryegrass x white clover (PRG), a complex multispecies mixture (n = 22 species) grasses, legumes, and forbs (CMS), and adjacent monocultures of perennial ryegrass, chicory, plantain, lucerne and red clover, which were sown longitudinally across the paddock and all available to cattle throughout the four-month finishing period. Cattle were then processed in a commercial abattoir and the tenderloin collected from each animal for metabolomic analyses. The remaining meat was minced (5mm plate), homogenised and processed into 250 g meat patties. A double-blind randomized cross-over clinical trial was then performed with 23 individuals that consumed a single meal of the meat. Metabolomic analyses were performed using a combination of GCMS/MS, lipidomics and LC-qToF-on plasma samples collected from all participants before meat consumption, 3-, and 5-h post prandial, in addition to meat and pasture samples. Metabolomic profiles of plant, meat and plasma were altered by the three forage mixtures. Metabolomic profiles of plant were different across all three sward mixtures, although CMS and AMS shared more similarities then PRG. However, metabolomic and lipidomic profiles of meat and plasma indicated the greatest differences were observed between AMS and CMS and PRG, which indicates grazing management may provide the greatest opportunity to manipulate metabolomics as opposed to maximising the plant species diversity of a pastoral diet. Gamma-tocopherol (Vitamin E) was elevated in plant material of the AMS diet and the plasma of those consuming AMS meat, compared with PRG or CMS. Fatty acid metabolism was also altered in meat and plasma of the AMS diet as eicosapentaenoic acid was elevated compared with PRG or CMS. Additional differences were also detected in untargeted analyses although features were unable to be matched to the in-house metabolite library. While many features were not able to be identified, these results are the first evidence that metabolomic profiles of the human consumer reflect not only the beef finished from different forages, but also meat and plasma reflect metabolomic profiles of the different sward mixes.