Background: The immune response of aged broiler breeder hens is influenced by many factors including obesity and aged lymphatic organs, but may improve by increasing the bioavailability of various nutrients such as zinc (Zn). Dietary supplementation of phytase can improve Zn availability in senescent broiler breeder hens.
Aims: The aim of this study was to investigate the effect of supplementary zinc oxide (ZnO) and phytase in a maize-soybean meal-based diet on immune responses of broiler breeder hens.
Methods: In a 2 × 4 factorial arrangement, a total of 128 hens were randomly assigned into eight groups. The birds received two levels of phytase (0 or 300 U/kg diet) and four levels of ZnO (30, 60, 90, and 120 mg/kg diet) for 13 successive wk (59-72 wk of age).
Results: Results showed that phytase supplementation significantly increased immunoglobulin M (IgM), cutaneous basophil hypersensitivity (CBH) responses, total number of leukocytes, percentage of lymphocytes, and heterophil to lymphocyte ratios. The percentage of basophils and monocytes, however, decreased with phytase supplementation. Supplementation of ZnO increased anti-sheep red blood cells (SRBC) antibody titer, IgM, CBH responses, the total number of leukocytes, and the percentage of lymphocytes. Dietary supplementation of ZnO decreased the percentage of heterophil, and heterophil to lymphocyte ratio. A significant interaction effect of phytase and ZnO was found on the total number of leukocytes and percentage of lymphocytes.
Conclusion: Dietary supplementation of ZnO (90 mg/kg diet) and phytase had some positive effects on improving immune responses in broiler breeder hens.
Keywords: Hen; Immunity; Leukocyte; Phytase; Zinc.