This document provides an overview of the lactation process in dairy cows. It discusses how milk is produced in the mammary gland and secreted, the mechanism of milk letdown triggered by oxytocin release, and various milking procedures and factors that affect milk quantity and quality. The document also describes the pathway that a nerve impulse travels to stimulate oxytocin release from the brain and the role of oxytocin in contracting cells in the udder to eject milk from alveoli. It notes that stress, pain or mistreatment can inhibit oxytocin release and milk letdown through the release of epinephrine.