PS9-10. Effect of Dried Seaweed (Ascophyllum Nodosum) on Performance and Plasma Metabolomics of Sheep.

Abstract This study investigated the effects of dried Ascophyllum seaweed supplementation on growth performance and plasma metabolomics in sheep. Eighteen crossbred Katahdin ewes of approximately (average BW = 25 ± 0.73 kg) were randomly assigned to either an unsupplemented basal diet (CON; n = 9) or a basal diet supplemented with 5 g/head/day of dried seaweed (DSM; n = 9) for a 35-d experimental period. Weekly blood samples were collected 5times. Plasma was prepared by centrifugation and composited for each sheep. We applied an untargeted chemical isotope labeling liquid chromatography–mass spectrometry (CIL LC-MS) analytical approach. A total of 601 metabolite features were detected. Volcano plot analysis identified 9 differentially abundant plasma metabolites (FDR < 0.05): 5 were upregulated including salicylic acid, trans-α-hydroxybenzylidenepyruvic acid and 3-indolepropionic acid while 4 were downregulated including1 of γ-amino-γ-cyanobutanoic acid, L-fucose, and valyl-alanine in supplemented sheep compared to controls. Receiver operating characteristic (ROC) curve analysis identified seven candidate plasma biomarkers, including: 2-oxoadipic acid, 3-indolepropionic acid, isomer 1 of γ-amino-γ-cyanobutanoic acid, valyl-alanine, cis/trans-2-methyl-5-isopropylhexa-2,5-dienoic acid, salicylic acid, and isomer 2 of γ-glutamyltyramine (FDR < 0.05; AUC > 0.85). Pathway enrichment analysis revealed perturbations in phenylpropanoid metabolism, tryptophan metabolism, and amino acid degradation pathways. These findings suggest that dried Ascophyllum nodosum seaweed supplementation induces measurable and biologically meaningful shifts in the plasma metabolome of sheep, particularly in antioxidant-related and amino acid metabolic pathways, with potential implications for health and production efficiency in small ruminants.