Milk is unarguably the most nutritious bio-fluid in all of nature. Milk sufficiency for neonatal brain, nervous and immune systems, and bone development and supportive tissue growth for even up to two years without a major need for alternative foods is evolutionary proof for its irreplaceable role in human nutrition. Milk production in ruminants is a bio-complex process that necessitates conversion of least available plant materials into the most enriched available nutrients. This book presents current research in the study of milk production, with a particular focus on the biological components and nutritional quality of milk.