Elucidating the role of prickly pear fruits (Opuntia littoralis) in mitigation of cadmium toxicity in Nile tilapia: impacts on haemato-biochemical and immunological responses

The study aimed to assess the promotional effects of dietary fruits of the prickly pear (Opuntia littoralis) on growth, haemato-biochemical, antioxidant, and immune activity and its possible regulatory roles after exposure to waterborne cadmium toxicity of Nile tilapia, Oreochromis niloticus. Fish were assigned to four groups fed on diets containing 0% (control, OLFE-0% group), 0.5% (OLFE-0.5% group), 1% (OLFE-1% group), and 2% (OLFE-2% group) of dietary prickly pear fruits for 60 days. Fish were exposed to subacute waterborne cadmium toxicity at the end of the feeding trial for an additional 4 days. Nile tilapia fed on OLFE-fortified diets enhanced their growth performance and digestive enzymes more than the control group, especially at 2% (OLFE-2%). Before and after the cadmium challenge, haemato-biochemical indices showed improvement in fish-fed OLFE compared to fish-fed OLFE-free diets. The activities of complement C3, lysozyme, catalase (CAT), total immunoglobulin, superoxide dismutase (SOD), and glutathione peroxidase (GPX) in prickly pear-treated fish groups compared to the control group before and after the cadmium waterborne challenge were increased, along with a significant decline in MDA levels, partially at OLFE-2%. In brief, the findings suggest that supplementing prickly pear fruits to tilapia diets, especially at a level of 2%, can enhance the immunological and antioxidant properties and effectively mitigate the harmful effects of Cd exposure in food safety and aquaculture.