Cattle and Their Diseases. Robert Jennings

      MILK-MIRROR [E.]

      In some countries cattle-dealers shave the back part of the cow. Just after this operation the mirrors can neither be seen nor felt; but this inconvenience ceases in a few days. It may be added that the shaving—designed, as the dealers say, to beautify the cow—is generally intended simply to destroy the milk-mirror, and to deprive buyers of one means of judging of the milking qualities of the cows. It is unnecessary to add that the cows most carefully shaven are those which are badly marked, and that it is prudent to take it for granted that cows so shorn are bad milkers.

      Milk-mirrors vary in position, extent, and the figure which they represent. They may be divided according to their position, into mirrors or escutcheons, properly so called, or into lower and upper tufts, or escutcheons. The latter are very small in comparison with the former, and are situated in close proximity to the vulva, as seen at 1, in cut E. They are very common on cows of bad milking races, but are very rarely seen on the best milch cows. They consist of one or two ovals, or small bands of up-growing hair, and serve to indicate the continuance of the flow of milk. The period is short, in proportion as the tufts are large. They must not be confounded with the escutcheon proper, which is often extended up to the vulva. They are separated from it by bands of hair, more or less large, as in cut marked F.

      MILK-MIRROR [F.]

      Milk-mirrors are sometimes symmetrical, and sometimes without symmetry. When there is a great difference in the extent of the two halves, it almost always happens that the teats on the side where the mirror is best developed give more milk than those of the opposite side. The left half of the mirror, it may be remarked, is almost always the largest; and so, when the perinean part is folded into a square, it is on this side of the body that it unfolds. Of three thousand cows in Denmark, but a single one was found, whose escutcheon varied even a little from this rule.

      The mirrors having a value in proportion to the space which they occupy, it is of great importance to attend to all the rows of down-growing hairs, which diminish the extent of surface, whether these tufts are in the midst of the mirror, or form indentations on its edges.

      These indentations, concealed in part by the folds of the skin, are sometimes seen with difficulty; but it is important to take them into account, since in a great many cows they materially lessen the size of the mirror. Cows are often found, whose milk-mirrors at first sight appear very large, but which are only medium milkers; and it will usually be found that lateral indentations greatly diminish the surface of up-growing hair. Many errors are committed in estimating the value of such cows, from a want of attention to the real extent of the mirror.

      All the interruptions in the surface of the mirror indicate a diminution in the quantity of the milk, with the exception, however, of small oval or elliptical plates which are found in the mirror, on the back part of the udders of the best cows, as represented in the cut already given, marked A. These ovals have a peculiar tint, which is occasioned by the downward direction of the hair which forms them. In the best cows these ovals exist with the lower mirrors very well developed, as represented in the cut just named.

      In short, it should be stated that, in order to determine the extent and significance of a mirror, it is necessary to consider the state of the perineum as to fat, and that of the fullness of the udder. In a fat cow, with an inflated udder, the mirror would appear larger than it really is; whilst in a lean cow, with a loose and wrinkled udder, it appears smaller. Fat will cover faults—a fact to be borne in mind when selecting a cow.

      In bulls, the mirrors present the same peculiarities as in cows; but they are less varied in their form, and especially much less in size.

      In calves, the mirrors show the shapes which they are afterwards to have, only they are more contracted, because the parts which they cover are but slightly developed. They are easily seen after birth; but the hair which then covers them is long, coarse, and stiff; and when this hair falls off, the calf's mirror will resemble that of the cow, but will be of less size.

      With calves, however, it should be stated, in addition, that the milk-mirrors are more distinctly recognized on those from cows that are well kept, and that they will generally be fully developed at two years old. Some changes take place in the course of years, but the outlines of the mirror appear prominent at the time of advanced pregnancy, or, in the case of cows giving milk, at the times when the udder is more distended with milk than at others.

      M. Mayne, who has explained and simplified the method of M. Guénon, divides cows, according to the quantity which they give, into four classes: first, the very good; second, the good; third, the medium; and fourth, the bad.

      In the FIRST class he places cows, both parts of whose milk mirror, the mammary—the tuft situated on the udder, the legs and the thighs—and the perinean—that on the perineum, extending sometimes more or less out upon the thighs—are large, continuous, and uniform, covering at least a great part of the perineum, the udder, the inner surface of the thighs, and extending more or less out upon the legs, as in cut A, with no interruptions, or, if any, small ones, oval in form, and situated on the posterior face of the udder.

      MILK-MIRROR [G.]

      Such mirrors are found on most very good cows, but may also be found on cows which can scarcely be called good, and which should be ranked in the next class. But cows, whether having very well developed mirrors or not, may be reckoned as very good, and as giving as much milk as is to be expected from their size, food, and the hygienic circumstances in which they are kept, if they present the following characteristics: veins of the perineum large, as if swollen, and visible on the exterior—as in cut A—or which can easily be made to appear by pressing upon the base of the perineum; veins of the udder large and knotted; milk-veins large, often double, equal on both sides, and forming zig-zags, under the belly.

      To the signs furnished by the veins and by the mirror, may be added also the following marks: a uniform, very large, and yielding udder, shrinking much in milking, and covered with soft skin and fine hair; good constitution, full chest, regular appetite, and great propensity to drink. Such cows rather incline to be poor than to be fat. The skin is soft and yielding; short, fine hair; small head; fine horns; bright, sparkling eye; mild expression; feminine look; with a fine neck.

      Cows of this first class are very rare. They give, even when small in size, from ten to fourteen quarts of milk a day; and the largest sized from eighteen to twenty-six quarts a day, and even more. Just after calving, if arrived at maturity and fed with good, wholesome, moist food in sufficient quantity and quality, adapted to promote the secretion of milk, they can give about a pint of milk for every ten ounces of hay, or its equivalent, which they eat.

      They continue in milk for a long period. The best never go dry, and may be milked even up to the time of calving, giving from eight to ten quarts of milk a day. But even the best cows often fall short of the quantity of milk which they are able to give, from being fed on food which is too dry, or not sufficiently varied, or not rich enough in nutritive qualities, or deficient in quantity.

      MILK-MIRROR [H.]

      The SECOND class is that of good cows; and to this belong the best commonly found in the market and among the cow-feeders of cities.

      They have the mammary part of the milk-mirror well developed, but the perinean part contracted, or wholly wanting, as in cut G; or both parts of the mirror are moderately developed, or slightly indented, as in cut H. Cut E belongs also to this class, in the lower part; but it indicates a cow, which—as the upper mirror, 1, indicates—dries up sooner when again in calf.

      These marks, though often seen in many