Effects of Nigella sativa on Performance, Blood Profiles, and Antibody Titer against Newcastle Disease in Broilers.

Recent anxiety about resistance to chemical drugs has elevated the position of phytogenic feed additives including Nigella sativa in preventive strategy in the poultry industry. During this study, a completely randomized experiment was designed to investigate the efficacy of different levels (0 to 16%) of N. sativa seeds supplemented in the diet of broilers on performance, immune responses, and hematological and biochemical parameters. The results indicated the following: (a) Supplementation of 1% N. sativa seeds in diet had the highest positive effects and 16% N. sativa had the highest significant (p=0.03) adverse effects on weight gain, while up to 2% N. sativa seeds in the diet reduced feed conversion ratio (FCR) whereas 4% and over that increased the FCR. (b) Chickens fed with a diet containing 1% N. sativa seeds had the highest antibody titers, but those fed with 16% N. sativa seeds had the lowest antibody titers at end of the experiment. (c) Dietary inclusion of N. sativa seeds increased hemogram parameters and the group fed with 16% N. sativa seeds had the highest values on day 21 until the end of the experiment. (d) Supplementation of N. sativa seeds decreased in WBC and lymphocytes but increased heterophils, H/L, monocytes, eosinophils, and basophils percentages. Supplementation of up to 2% of N. sativa seeds in broiler's diets elaborated serum level of those parameters, while supplementation of ≥ 4% N. sativa seeds decreased their serum levels. In conclusion, supplementation of N. sativa seed (1-2%) in broiler diets, as a multipurpose natural growth promoter, improves performance, elevates humoral immune responses, affects serum biochemical profiles of broiler chickens, and induces changes in their hemogram and leukogram, while there are no side, residual, and hazardous effects.