Protective role of bentonite against aflatoxin B₁- and ochratoxin A-induced immunotoxicity in broilers

The present study was designed to investigate any ameliorative effects of bentonite (BN) against immuno-pathological alterations induced by dietary aflatoxin B₁ (AFB₁) or ochratoxin A (OTA) in broiler chicks. In one experiment, AFB₁ (0.1, 0.2 or 0.6 mg/kg feed) was fed alone and par alley with bentonite clay (3.7 or 7.5 g/kg feed) to the broilers. In the second experiment, the broilers were given feed contaminated with OTA (0.15, 0.3 or 1.0 mg/kg feed) alone and in combination with bentonite clay (3.7, 7.5, or 15 g/kg feed). Experimental feedings were continued for 42 days. At various time points along the feeding schedule, immune system organ histologic status, as well as host humoral and cellular immune responses, were evaluated in all groups. The dietary addition of AFB₁ and OTA alone significantly reduced immune responses in the birds as assessed by histological changes in the bursa of Fabricius and thymus, antibody responses to SRBC, in-vivo lympho-proliferative responses to Phytohemagglutinin-P (PHA-P) and, phagocytic function in situ. The dietary addition of BN significantly ameliorated the immunotoxicity of 0.1 and 0.2 mg/kg dietary AFB₁, however with a level of 0.6 mg AFB₁/kg only partial amelioration was seen. The co-treatment of birds exposed to OTA with BN at all levels only partially alleviated deleterious effects on histology and immune responses. Taken together, the results here suggested to us that dietary addition of BN could help ameliorate AFB₁-mediated immunotoxicities but could not afford such protection against OTA-induced immune damage.