Plant active principles are chemical compounds present in the entire plant or in specific parts of the plant that confer them therapeutic activity or beneficial effects. These substances have low molecular weight and are derived from the plant secondary metabolism, including glucosides, alkaloids (alcohols, aldehydes, ketones, ethers, esthers, and lactones), phenolic and polyphenolic compounds (quinones, flavones, tannins, and coumarins), terpenoids (mono- and sesquiterpenoids, and steroids), saponins, mucilages, flavonoids, and essential oils. Phytogenic feed additives are non antibiotic growth promoters. So, they are giving more attention to the indigenous medicines i.e phytogenic products such as herbs (flowering, no woody and non persistent plants), spices (herbs with an intensive smell or taste commonly added to human food), essential oils (volatile lipophilic compounds derived by cold expression or by steam or alcohol distillation), oleoresins (extracts derived by nonaqueous solvents).