Injection of Cinnamomum osmophloeum leaf extract enhances physiological and immune responses in Macrobrachium...

This study investigated the immunomodulatory and physiological effects of Cinnamomum osmophloeum leaf extract (CE) in Macrobrachium rosenbergii through injection. Three doses (1.5, 3.0, and 6.0 μg prawn^-1) were administered, and immune responses were monitored within 48 h. The medium dose (CE3.0) consistently elevated total haemocyte count (THC) and differential haemocyte count (DHC) from 12 to 24 h post-injection, while phenoloxidase (PO) activity significantly increased at 24 h in CE3.0 and at 48 h in CE1.5. Enhanced respiratory burst (RBs), phagocytic activity, lysozyme activity, and bacterial clearance were also observed, particularly in CE3.0, which significantly improved survival against Lactococcus garvieae at 168 h post-infection. Although CE3.0 and CE6.0 induced transient hyperglycemia at 12 h, glucose levels normalized thereafter, and no significant changes in lactate levels were detected. These results demonstrate that C. osmophloeum extract can enhance innate immunity and disease resistance in M. rosenbergii. As a preliminary investigation, this study provides foundational data for future development of C. osmophloeum leaf extract as a potential immunostimulant feed additive in aquaculture.