As the main place of digestion and absorption of nutrients, the digestive system is of special importance in the economic productivity of the herd. The intestines are constantly exposed to various substances in food, toxins, bacteria, fungi and viruses. On the other hand, the bacterial population of the intestinal flora plays a very important role in maintaining the health and efficiency of the digestive system. Therefore, maintaining this flora and preventing the excessive growth of pathogens is a very vital issue in poultry farming.