Effects of supplementing with Nigella sativa meal and selenium nano-particles on growth performance, immunity, microbial count, oxidative stability, and intestinal integrity-related gene expression in heat-stressed growing rabbits

Heat stress severely impacts the performance of growing rabbits, compromising their survival and hampering the sustainability of rabbit farming. Therefore, this study investigated the effects of nano-selenium, Nigella sativa meal, and their mixture supplementation on immune responses, antioxidant activity, gut health, and growth performance in growing rabbits. One hundred male New Zealand White rabbits were equally divided into four groups, each with five replicates at 35 days of age (5 rabbits/replicate). The control group was fed on a basal diet (CON) while the other groups were fed a basal diet supplemented with Nigella sativa meal (NSM, 40 g/kg), Nano-selenium (Nano-Se, 0.1 mg/kg), and their mixture (Se-NSM), respectively. Results showed that exposure of growing rabbits to heat stress resulted in a significant deterioration in growth performance and immune-oxidative status. Additionally, feeding rabbits with Se-NSM enhanced body weight gain, carcass weight, and feed conversion ratio. Se-NSM supplementation increased the digestibility of dry matter, crude fiber, and crude protein, and increased the activity of lipase and trypsin enzymes. Superoxide dismutase (SOD), total antioxidant capacity (TAC) activity, and triiodothyronine (T3), IgA, and IgG levels increased, while malondialdehyde (MDA) decreased in rabbits receiving Se-NSM supplementation. Adding Se-NSM decreased triglycerides, cholesterol, and LDL levels, while increasing glucose, total protein, and AST levels in rabbits. Supplementing Se-NSM enhanced gut health via reducing pathogenic microbes counts and mucin-2 (MUC-2) and cationic amino acid transporter-1 (CAT-1) gene expression. These findings indicate that combining Nano-selenium-Nigella sativa meal enhanced the rabbits’ growth performance, immune response, and gut integrity during heat stress.