There is always a need for enhanced disease resistance, feed efficiency and growth performance in poultry industry as well as in fisheries and aquaculture. The cost of production are likely to be reduced if growth performance and feed efficiency are increased in commercial poultry production and aquaculture. Also, if the survivility increase, then their overall production cost would be remarkably reduced. Dietary supplementation of different feed additives e.g. immunostimulants, probiotics and prebiotics usually in small quantities for the purpose of fortifying it with certain nutrients have been found to be beneficial for improving immune status, feed efficiency and growth performance of poultry and finfishes.