Probiotics are defined as live microorganisms thought to be healthy for the host organism. An animals gastrointestinal tract or gut naturally contains numerous bacteria that assist the body in numerous physiological functions. Animals begin life with a sterol gut and begin obtaining the various bacteria that live in the large intestine at birth, as the body develops it populates the large intestine with the optimal types and levels of bacteria needed to be healthy. Because several factors effect the bodies ability to maintain optimal levels of bacteria the use of probiotics is a highly effective method of re populating the body with healthy bacteria.