Metabolites associated with the inclusion of Atlantic GRO¹ seaweed supplementation as a methane mitigation str

This study evaluated plasma metabolomic responses to Atlantic GRO¹ brown seaweed supplementation at 0.0%, 0.5%, 1.0%, and 2.0% of diet dry matter in replacement beef heifers. Plasma metabolites were analyzed using direct flow injection/liquid chromatography–tandem mass spectrometry (DFI/LC–MS/MS), and a total of 453 plasma metabolites were quantified.

Significant dose-dependent metabolic shifts were observed, particularly at the 1.0% and 2.0% supplementation levels (p < 0.05). The 2.0% seaweed group showed alterations in valine, TG.18:0_38:6, asymmetric dimethylarginine (ADMA), C2 acylcarnitine, trimethylamine (TMA), and inosine (p < 0.05, AUC ≥ 0.75, VIP score >1, MDA > 0), mainly involving lipid and amino acid metabolism.

Methane-emission groups also differed in metabolites associated with energy metabolism and microbial fermentation pathways, with urea and ethylmalonic acid (EMA) identified as potential biomarkers (p < 0.05, AUC ≥ 0.75, VIP score > 1, MDA > 0). Overall, 152 metabolites were significantly affected by the interaction between seaweed supplementation and methane-emission group (p < 0.05), indicating that the metabolic response depended on methane phenotype.

Metabolite differences were greatest between moderate and high methane emitters, with interaction-related changes mainly involving triglycerides, phosphatidylcholines, and microbial compounds, reflecting changes in lipid metabolism, nitrogen homeostasis, and gut microbial activity.

Pathway analysis revealed enrichment of arginine biosynthesis, purine metabolism, and branched-chain amino acid metabolism, particularly at higher supplementation levels.

Overall, Atlantic GRO¹ seaweed induced dose-dependent metabolic changes associated with methane reduction and supports the potential use of plasma metabolites as non-invasive biomarkers of enteric methane emissions in cattle.