RESUMEN
The antibiotic residues and pathogenic resistance against the drug are very common in poultry because of antibiotics used in their feed. It is necessary to use natural feed additives as effective alternatives instead of a synthetic antibiotic. This study aimed to investigate the immune response of Nigella sativa and Curcuma longa in broilers under biological stress against Pasteurella multocida. The total 100, one-day-old chicks were divided into 5 groups. Groups 1 and 2 served as control negative and control positive. Both control groups were receiving simple diet without any natural feed additives, but the infection was given in group 2 at day 28 with the dose of 5.14 × 107 CFU by IV. Groups 3A and 3B were offered 2% seed powder of Nigella sativa, groups 4A and 4B were offered C. longa 1% in powdered form, and group 5A and 5B were offered both C. longa 1% and N. sativa 2% in the feed from day 1 and groups 3B, 4B, and 5B were challenged with P. multocida. The haemagglutination inhibition titter against Newcastle Disease virus (NDV), feed conversion ratio, mortality, gross, and histopathology were studied. The results of this study revealed that hemagglutination inhibition titers against NDV were highly significant (P < 0.05) in treated groups, highest titers (3A, 6.8; 3B, 6.4; and 5A, 7.2) were obtained from treated Groups. The feed conversion ratio of N. sativa + C. longa treated groups (5A, 1.57, and 3A, 1.76) were higher than that of other nontreated groups. The gross and histopathological changes were much severe in control positive, but fewer changes were seen in treated groups. Therefore, we recommend that natural feed additives, black cumin (N. sativa) and turmeric (C. longa), act as an immune enhancer in broilers against P. multocida.