MILK SECRETION.

King Country Chronicle, Volume XXV, Issue 3263, 5 February 1931, Page 2

MILK SECRETION.

NERVES PLAY A BIG PART. Milk secretion and milking is discussed by Mr. Stephen Bartlett, of the National Institute for Research in Dairying, in the Berkshire Milk-re-cording Society’s Handbook. Some causes of variation in quantity in quality of milk are, he tells us: — (1) Those causes .that affect the speed at which milk is secreted or made in the udder between milking times.

(2) Those causes that tend to induce a cow to hold up a proportion of her milk at milking times. Under the first heading it is known that secretion by many of the body glands is reduced by insufficient food, illhealth, or disease, fear, anger, and discomfort. Also there are other well-known factors that affect the speed of milk secretion, such as stage of lactation and age of the cow, as well as that secretion becomes slower as the quantity of milk in the udder increases.

Under the second heading one of the chief points to be noted is that the strippings of any cow are almost invariably rich in fat, sometimes being as rich as thin cream, so that retention of varying quantities of this rich milk will affect the quality of milk yielded by a cow more than it affects the quantity, and this can account for a considerable amount of the fluctuations that occur in the fat content of milk of cows from day to day. It is possible that this holding up of portions of milk at milking time is associated with the difference in fat contents that occur between morning and evening milk'when unequal night and day intervals occur, but since conclusive evidence cannot be offered, it is not desirable to emphasise the point. Since accumulated milk in the udder checks the rate of secretion, it will be obvious that milk retained at one milking will retard the rate of secretion before the next milking and that the effect of inefficient milking is to create a type of vicious circle which reduces milk yield. If cows are always treated in such a manner that they never suffer any unnecessary discomfort, nor have any reason to sense danger from their masters, there is less likelihood of milk being held up at milking time. It is only reasonable to expect some cows to possess more uneven temperaments than others, and so one cow may be affected by a disturbance that another fails to notice. It has been found that milk secretion is not controlled by the nerves, for a cow can secrete milk when the nerves of the udder do not function; at the same time there is no doubt that during the actual milking process nervous control plays an important part, and that unless a cow experiences a pleasurable sensation, free from fright, during milking time, it is unlikely that all the milk will be drawn.