Nano-selenium, organic selenium, and novel selenium sources: Which is best for clean and sustainable poultry production?

Selenium (Se) is one of the most widely used feed additives in poultry farms because Se is required to activate antioxidant enzymes, specifically glutathione peroxidase and various types of proteins called selenoproteins. Thus, Se plays several roles such as maintaining the efficient functioning of poultry organs by protecting their cell membranes against oxidative damage caused by free radicals and other chemical compounds generated during normal metabolism. Se supplementation is commonly applied to boost fertility in poultry breeders' farms. Se is added to poultry diets to maintain poultry productivity by relieving the negative impacts of undesirable conditions such as heat stress, high stocking density stress, vaccination, mycotoxins, and heavy metal contamination. Moreover, Se is required by the human body and the daily Se requirement can be readily satisfied by consuming cheap products such as poultry meat and eggs, so poultry producers must supplement poultry diets with Se to produce suitable meat and eggs for humans. Different Se sources are available on the market and several attempts have also been made to produce novel Se sources in laboratories. These diverse sources cause confusion among poultry producers when selecting a Se source. Therefore, it is necessary to identify Se sources that are the best choices to allow poultry producers to achieve different aims without deleterious impacts on the environment. Consequently, the aims of this review are to help poultry producers to select suitable Se sources, support companies in the production of Se and provide initial evaluations of Se products to enable poultry producers to immediately obtain information from the label, and aid researchers in the development of novel competitive Se sources.