**5. Conclusions**

The use of functional AA such as Arg, Thr, and Met to improve the health and productivity of birds exposed to immune challenges is promising. It has been proposed that functional AA can help the immune system fight intracellular pathogens. It is necessary to determine whether episodes of immunosuppression caused by stress can be overcome by functional AA in field-raised birds, as well as to define the strategic use to reduce disease risk. It is also possible that functional AA should be supplemented during or after an immunological challenge to help affected individuals recover and return productive parameters to prechallenge levels.
