External Parts of Dairy Cattle

There are six major breeds of dairy cattle: Holsteins, brown Swiss, Jerseys, Ayrshires and milking shorthorns. Of these six, Holsteins are the most popular in the United States. Dairy cows have several external body parts which aid in milk production. The most obvious is the udder, which is a low hanging mammary gland that produces the cow's milk.

  1. Udder

    • A dairy cow's udder must be released of milk at least two times a day during lactation periods.

      The udder, or mammary gland, of a dairy cow is a large organ located between its back two legs. A dairy cow starts producing milk within its udder after it has given birth to its first calf. This is because the milk serves as food for the young calf. When a dairy cow is lactating, it must be milked two times a day, releasing the swollen udder of the milk that has accumulated there. Dairy cows usually produce about 5 to 7 pounds of milk a day.

    Mammary Vein

    • The mammory vein is a visible, protruding vein that supplies the udder with blood.

      It is important that blood is supplied to the udder of a dairy cow. At any given time, lactating cows' udders hold about 8 percent of their body's blood volume. Blood reaches the udder by means of the mammary vein, which is a large vein visible on the cow's side beside the udder.

    Teats

    • Teats are the valves which release the milk from the udder.

      The teats are the elongated nipples attached to the udder. They serve as the only exit for secretions from the udder and the means by which the calf receives its milk. Teats are free of sweat glands, hair and sebaceous glands. Usually, teats are about 6.6 centimeters in length, though this can vary depending on the size of the cow. The cavity within the teat is called the teat cistern. During milking, this cavity fills with milk and is released.

    Hooves

    • Hooves, though not directly a part of the mammary system, are important to keep healthy in order to maintain milk production.

      A cow is a bovid animal, meaning that it has a cloven foot, or hoof. A cloven hoof is split into two toes. Each toe is covered by a layer of horn, or hard material at the end of the foot. Hoof health is an important part of dairy cow milk production because the hooves must be kept healthy in order for the cow to produce the amount of milk desired from dairy farmer. Dairy farmers regularly trim dairy cows' hooves to keep them comfortable.