DIETARY EFFECT OF NIGELLA SATIVA MEAL ON GROWTH PERFORMANCE, BLOOD BIOCHEMISTRY, IMMUNITY, INTESTINAL MICROBIAL, AND MUC-2 GENE EXPRESSION OF GROWING RABBITS UNDER ENVIRONMENTAL HEAT STRESS

This study aimed to evaluate the effect of different dietary levels of Nigella sativa meal (N growth performance, serum metabolites, immune response, intestinal microbiota and MUC-2 gene expression in growing rabbits under environmental heat stress. Two hundred and fifty, 3- 5day-old male New Zealand white rabbits were randomly assigned to five experimental groups with five replicates each. The experimental groups were as follows: NSM0, a basal diet serving as the control; NSM1, NSM2, NSM3, and NSM4 were supplemented with 10, 20, 30, and 40 g/kg Nigella sativa meal, respectively. The results showed significant improvements in body weight gain, feed conversion ratio, and carcass weight (P ≤ 0.05) in NSM3 and NSM4 compared to the other groups; however, feed intake and other carcass traits were unaffected. Feeding NSM3 and NSM4 also led to increased digestibility of dry matter and crude protein compared to the other groups. Furthermore, NSM supplementations significantly increased serum immunoglobulins (IgM and IgG), high-density lipoprotein (HDL), and total protein (P ≤ 0.05), while significantly reducing triglycerides, low-density lipoprotein (LDL), and total cholesterol (P ≤ 0.05). Moreover, NSM supplementation significantly modified the cecal microbiota in NSM4 by increasing the number of Lactobacillus and decreasing the number of E. coli (P ≤ 0.05). In addition, the up-regulation of MUC-2 gene expression (P ≤ 0.05) in rabbits fed NSM3 and NSM4 compared to the other groups. It can be concluded that supplementing with Nigella sativa meal with level of NSM3 and NSM4 can enhance growth performance, immunity, lipid profile, and intestinal integrity by modifying gene expression and microbial content in rabbits exposed to environment heat stress. This may provide an effective means of mitigating the detrimental effects of heat stress.