Lifestock refers to any animal breed kept by humans for commercial purposes. This book focuses on the effects of certain types of foods, such as prebiotics, on the physiology and performance of animals. Research is included on the digestibility and the nitrogen balance of diets containing different protein sources. A review of the effect of polyphenolics on animal productivity and health is also given, as well as a review of models based on milk fatty acid patterns to predict nutrient supply, methane emission, and metabolic disorders. Related to this, the Greenhouse Gas emissions from a Canadian dairy industry is examined. Finally, lifestock diseases compromise animal welfare, reduce productivity and in some cases, infect humans. A review on how to monitor a number of infectious diseases that are of particular economic importance to the dairy cattle industry are discussed. Disease management is also reviewed.