RESEARCH WORK

Wairarapa Times-Age, 17 April 1939, Page 3

RESEARCH WORK

STRUCTURE OF COW'S UDDER. The udder of the dairy cow has a most complex internal structure. 11 consists of a mass of blood vessels, nerves, muscle, fat, milk ducts, veins and arteries, which form a soft, spongy, greyish pink whole. The skin enclosing it is thin and silky, and covered with soft fine hair. The udder varies very much in size and shape, as Well as in its secreting capacity in different individuals. Some have more connective and fatty tissue than others and these are known as “fleshy” udders. Though often large and well-shaped, they are nevertheless deficient in true secreting Capacity, and are considerably more subject to inflammation and inflammatory disease than those with less fatty tissue. A good udder on being milked out should decrease rapidly in size' and hang in loose folds of soft elastic skin. Above each of the teats is a cavity known ad a “milk reservoir,” which has a capacity of about a pint, and which holds the milk made in other parts of the udder until it is drawn by the act of milking. From each reservoir a tube leads through the centre of the teat beneath it, but the milk is retained by bands of muscle known as the “sphincter muscle” surrounding each tube. Sometimes, however, these muscles are weaker than they should be, and a very small pressure suffices to open the canal, with the result that the cow leaks her milk —it may even go so far as to leak in four solid streams in some individuals and causes great inconvenience and loss. On the other hand, the sphincter muscles of some animals are so powerful that it requires a' strong effort of the hand to draw any milk. A vertical partition runs the length of the udder from back to front, dividing it into two distinct parts, each of which is known as the milk gland, and has a complex structure. Here are to be found the blood vessels and capillaries which carry blood to every part of the udder and the nerves which control the manufacture of the milk. The' remainder consists chiefly of a mass of small sac-like bodies called gland-lobules. Arranged like grapes on a stalk, the main stalk corresponds to a narrow tube, called the milk-duct. From this, many smaller tubes branch off, at the end of each of which is a gland lobule. The inside of each lobule contains a number of small bodies, called the alveoli.

Rounded at one end, they taper slightly to a neck at the other, and it is in these that the actual formation of the milk takes place. The stimulus produced by the act of milking immediately sets the cells in the alveoli into a state of .increased action, whereby they extract from the blood those constituents necessary to make milk, and pass it into the branch ducts of the lobules, from them into the main duct and so it trickles down into the reservoir over the teat.