1,8-cineole and ginger extract (Zingiber officinale Rosc) as stress mitigator for transportation of largemouth bass (Micropterus salmoides L.)

Transportation stress is considered the major cause of production and economic losses in aquaculture. Here, we examined the effects of dried ginger extract (GE) and 1,8-cineole (CIN) on juvenile largemouth bass (Micropterus salmoides) subjected to simulated transport by quantifying serum metabolites, antioxidant enzyme activity, and haematological features in conjunction with whole transcriptome analysis. Under transportation stress, the addition of dried ginger extract (20 μg/L) or 1,8-cineole (30 μg/L) significantly reduced serum cortisol levels in juvenile largemouth bass. Additionally, CIN administration was associated with a significant increase in total protein and glucose levels in serum, and reduced alkaline phosphatase (AKP) and alanine aminotransferase (ALT) enzyme activity. GE and CIN significantly increased serum lysozyme activity, glutathione peroxidase (GSH-Px) activity and total antioxidant capacity (T-AOC), thereby counteracting lipid peroxidation. Transportation stress-induced malondialdehyde (MDA) production was reduced under exposure to GE and CIN, while white blood cell (WBC) counts were increased in the treatment group compared with controls. Whole transcriptome analysis of M. salmoides liver tissue identified 533 significantly differentially expressed genes (DEGs) between the CIN and transport-only control treatment groups. DEGs were mainly enriched in endocrine system, immune system and metabolic pathways. This study demonstrates that dried ginger extract or 1,8-cineole can potentially regulate M. salmoides response to transportation stress, thereby providing novel insights into the mechanisms underlying immune response and antioxidant pathways during sedation, supporting 1,8-cineole as an effective potential antioxidant agent in aquaculture.