Saffron-derived crocin modulates growth, immunity, metabolism, antioxidant capacity, and disease resistance to Aeromonas hydrophila in the oriental river prawn (Macrobrachiumnipponense).

The present study investigated the effects of dietary crocin supplementation on growth, physiological homeostasis, immune competence, and disease resistance in the oriental river prawn (Macrobrachium nipponense). Juvenile prawns (initial weight: 1.35 ± 0.06 g) were fed experimental diets containing 0.00, 0.05, 0.10, 0.15, or 0.20 g/kg crocin for 60 days. Crocin supplementation resulted in significant improvements in final weight (FW), weight gain (WG), specific growth rate (SGR), feed conversion ratio (FCR), hepatosomatic index (HSI), and survival rate. Hemato-biochemical profiling demonstrated pronounced reductions in urea, uric acid, glucose, creatinine, and triglyceride levels, alongside elevated high-density lipoprotein (HDL) and low-density lipoprotein (LDL) concentrations. Key immune indicators, including albumin (ALB), total protein (TP), lysozyme (LYZ), phenoloxidase (PO), total hemocyte count (THC), and phagocytic activity, were significantly enhanced, whereas crustacean hyperglycemic hormone (CHH) levels and micronucleus (MN) frequency were markedly suppressed. Antioxidant enzyme activities were substantially elevated, accompanied by a notable decline in malondialdehyde (MDA) content. Dietary crocin also enhanced digestive enzyme activities and promoted a favorable shift in intestinal microbiota, characterized by increased lactic acid bacteria (LAB). Moreover, crocin supplementation facilitated carotenoid deposition and improved muscle physicochemical properties. Transcriptional analysis revealed robust upregulation of genes associated with growth, metabolism, and immune function. Importantly, prawns fed the diet containing 0.10 g/kg crocin exhibited the highest post-challenge survival against Aeromonas hydrophila. Collectively, these findings demonstrate that crocin acts as a potent multifunctional carotenoid, enhancing growth performance, immune resilience, oxidative balance, and disease resistance.