Effects of <i>Rhodotorula mucilaginosa</i> on Growth, Antioxidant, and Immune Function, and Toll/Imd and JAK‐STAT Signaling Pathways in Red Claw Crayfish ( <i>Cherax quadricanatus</i> )

In aquaculture, the use of probiotics to improve growth, immunity, and stress resistance in crustaceans has gained increasing attention. This study examined the effects of incorporating different levels of <i>Rhodotorula mucilaginosa</i> (0.0, 0.1, 1.0, and 10.0 g/kg) into the diet on growth performance, antioxidant capacity (AOC), immune function, Toll/Imd, and JAK-STAT signaling pathways in red claw crayfish (<i>Cherax quadricanatus</i>). The investigation was conducted through a 56-day feeding trial. The main results are as follows: Compared with the control group (0.0 g/kg), different <i>R. mucilaginosa</i> levels significantly increased (<i>p</i> < 0.05) the specific growth rate (SGR) and weight gain rate (WGR) of red claw crayfish, significantly increased (<i>p</i> < 0.05) the activities of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPX), glutathione S-transferase (GST), total AOC (T-AOC), and acid phosphatase (ACP) in hepatopancreas of red claw crayfish, and significantly upregulated (<i>p</i> < 0.05) the relative expression levels of tumor necrosis factor receptor-associated protein 6, akirin, immunodeficiency homolog, interferon regulatory factor 4, Toll-like receptor (TLR) 6, TLR 2, Janus kinase, signal transducer activator of transcription, tumor necrosis factor α, interleukin-1β, transforming growth factor-β1 genes in the hepatopancreas of red claw crayfish. In conclusion, <i>R. mucilaginosa</i> significantly enhanced red claw crayfish's growth, AOC, and immune function, and activated the Toll/Imd and JAK-STAT signaling pathways. In this experimental context, the ideal addition level of <i>R. mucilaginosa</i> is 1.0 g/kg.