Abstract: Selenium (Se) is an essential trace element of fundamental importance to antioxidant system, immune cell function, growth-promoting, sperm formation and swimming, function of prostaglandin. It present within at least 35 selenoproteins.Glutathione peroxidases (GPx1-GPx6) and thioredoxin reductases (TrxR1-TrxR3) play important role due to its antioxidant. Sodium selenite is used as the commercial Se source supplement in animal feeds in the China, but sodium selenite exists many problems such as lower absorption rate, peroxidation and potential contamination. Organic selenium and nano-selenium have many advantages such as increase absorption rates, biological activity, and reduce environmental pollution. Nano-selenium compared with the organic selenium have more significant efficiency and lower toxicity. nano-selenium is the lowest toxicity of Se source already founded. In recent years, the research of Nano-Se substitute for organic selenium and inorganic selenium sources has become a hot spot.

Key words: nano-selenium; animal nutrition; antioxidant