There are many factors such as dietary and management which, have been shown to markedly affect the structure and activities of gut microbial communities in livestock animals. Under stressed conditions, direct-fed microbials may be used to reduce the risk or severity of scours caused by disruption of the normal intestinal environment. . Prebiotics are nondigestible dietary ingredients, usually oligosaccharides (OS), which provide a health benefit to the host by directly modulating the gut microbiota. The observable benefits of prebiotics may also be minimal in generally healthy calves In coming days, it is expected that prebiotics could be the part of diets in both ruminants and non-ruminants for enabling modulation of gut microfloravis a vis animals productivity in ecological ways. This review mainly focused on the benefits of probiotics/prebiotics on the GI microbial ecosystem in ruminants, which is deeply involved in nutrition and health for the animal. However, it is necessary to conduct more research with prebiotics as feed additives to understand the detailed mechanisms of action and identify better alternatives for animal production and health.