Partial replacement of dietary fish oil by beef tallow does not impair antioxidant capacity and innate immunity of red swamp crayfish, Procambarus clarkii

Beef tallow (BT) has attracted research interests of fish oil (FO) sparing in aquafeed, but total replacement of dietary FO by BT might damage aquatic animal health as a controversial issue for years. This study aimed to investigate the effects of BT partially or completely replacing FO on the health of red swamp crayfish (Procambarus clarkii), especially antioxidant capacity and immune response. Three experimental diets containing FO, BT and a blend of FO and BT (FB, 1:1) as lipid sources, respectively, were formulated to feed crayfish for 8 weeks. The results showed crayfish exhibited no significant differences (p > 0.05) in growth and body proximate composition regardless of dietary lipids. Crayfish fed a BT diet were observed higher contents of haemolymph triglyceride and free fatty acid (FFA) compared with crayfish fed FO (p