Abstract: Aflatoxins are mainly a class of highly toxic secondary fungal metabolites produced by Aspergillus flavus and Aspergillus parasiticus. Most grains and animal feeds around the world are polluted by aflatoxins, which poses a severe threat to animal health and the sustainable development of livestock and poultry breeding industry. Aflatoxin B₁（AFB₁） is a common and highly toxic mycotoxin. Excessive intake of AFB₁ has a series of toxic effects such as carcinogenesis, teratogenesis and immunosuppression. A large number of studies have confirmed that AFB₁ can seriously affect the growth, immune function and organ development of broiler chickens, and threaten the healthy development of poultry industry. Combined with the research reports in China and abroad, this paper summarizes the properties and toxicity of aflatoxins, and expounds the research progress on the toxic effects of AFB₁ on broiler chickens from the four aspects of intestinal dysfunction, immunosuppression, organ damage and genetic toxicity, which may provide a reference for further elucidating the molecular mechanism underlying the toxic effects of aflatoxins in broiler chickens and for mitigating their risk in broiler farming.

Key words: aflatoxin B₁, toxicity, broiler chickens, immunosuppression