The efficacy of immune system may be deregulated by various exogenous and endogenous factors which impair the immunohomeostasis of birds and their elimination is not always possible. As a result, birds become more prone to secondary disease conditions and show poor growth even if provided feed ad libitum and ultimately resulted in low feed conversion ratio and productivity. One of the practical methods to protect the immunobalance is by the use of pharmacological immunomodulators. Although vaccines and antibiotics have contributed a lot in controlling infectious diseases but frequent...