Cows, like all mammals, produce milk to nourish their young. Instead of breasts, cows possess an udder, a specialized organ for milk production.
Cow Udder Anatomy
A cow’s udder is a single, large organ located between her hind legs. It is composed of four distinct mammary glands, commonly called “quarters.” Each quarter functions independently, meaning milk produced in one gland does not transfer to another. The quarters are divided into two forequarters and two rearquarters, with rear quarters often having greater milk capacity.
Connected to each of these four quarters is a single projection known as a teat. A cow has four teats. Each teat contains a teat cistern, which stores milk, and a narrow teat canal, also called the streak canal, that serves as the exit point for milk. This canal is protected by smooth muscle that keeps it closed between milkings and is lined with keratin, a waxy substance that acts as a natural barrier against bacteria.
The Purpose of Teats
The primary purpose of a cow’s udder and teats is to produce and deliver milk to her offspring. Milk synthesis occurs within millions of microscopic sacs called alveoli. These alveoli are lined with specialized epithelial cells that convert nutrients from the cow’s bloodstream into milk components. An extensive blood supply supports this process, with approximately 500 liters of blood flowing through the udder for every liter of milk produced.
When a calf suckles or the udder is prepared for milking, a sensory nerve response triggers the release of the hormone oxytocin. Oxytocin causes tiny muscle-like cells surrounding the alveoli to contract, forcing the newly synthesized milk into a network of ducts and cisterns for removal through the teats. This physiological process, known as milk let-down, ensures efficient milk delivery.
Udder Health and Milk Production
Maintaining udder health benefits both the cow’s well-being and milk quality. Infections, such as mastitis, can lead to reduced milk quantity and quality, often indicated by an increased somatic cell count. Proper hygiene and management practices on dairy farms prevent such conditions.
Dairy operations use mechanical milking machines, which are sanitary and comfortable for cows compared to traditional hand milking. The milking process involves several steps:
Preparing the teats with an antiseptic solution.
Fore-stripping to check for abnormalities and stimulate milk let-down.
Attaching the milking unit.
Applying a post-milking teat dip to protect the teat canal from bacteria.
These natural defenses, including the keratin plug and sphincter muscle, prevent bacterial entry between milkings, highlighting the need for healthy teat ends.