Probiotics are live microbial feed supplements that beneficially affect the host by improving its intestinal microbial balance. The microorganisms come from a whole range of defined strains of probiotics belonging to the groups of lactic acid bacteria, Bacillus spores, and yeasts. Research in nutritional physiology demonstrates the critical importance of a balanced gut microflorain in animal and human physiology. The probiotic concept is concerned with optimizing nutritional intake and digestion by promoting the gut flora perspective. Probiotics act by reducing the feed conversion, resulting in an increase of the daily live weight gain. The improvement of the growth of an animal is achieved through a natural, physiological way: improving digestion by balancing the gut flora, helping the animal to fulfill its genetic potential. This book discusses probiotics' mode of action and probiotics' practical application in poultry production, while explaining the use of probiotics in preventing and fighting poultry diseases, such as Salmonellosis, Necrotic Enteritis, Coccidiosis, bacterial lameness, etc. It will be essential reading for a wide group of readers, including university staff, feed mill companies, poultry producers, veterinarians, and researchers in the field. Subject: Animal Science, Veterinary Science, Poultry Farming, Agriculture]