Grass and dried grass, or hay, represent a typical food for the horse, upon which he can subsist, become fat, and even perform a certain amount of slow work without any other kind of subsistence. Grasses are divided into natural and artificial. The former are true grasses, and the artificial include the clovers, sainfoin, lucerne, etc. - plants which are really not grasses. The natural grasses comprise upland, meadow, and water-meadow grass; though this is rather an arbitary division, as many grasses which grow on uplands are also to be found in meadows. The soil upon which the grasses grow considerably influences their value for feeding purposes; on rich soils the pastures are more permanent, but the produce is better for rearing and feeding animals; but on poor, light soil the grass is difficult to maintain, and indifferently nutritious.

Grass in its natural state is not usually given to horses in the United Kingdom, as it is more convenient and useful to give it in a dried condition - i.e., converted into hay; for though in warmer climates horses can perform a fair amount of work on it, yet here it has not the same amount of sustenance, and if it is young is liable to act as a laxative or purgative.

Water-meadow hay is not good for horses, and contains aquatic plants. Of the meadow and upland hay, the latter is considered the best. It is short, fine, has a pleasant odour and taste, hard and crisp stem, and is generally mixed with some of the artificial grasses, as clover. Its colour varies according to the way in which it has been prepared, though it rather inclines to green. In good upland hay the flowering heads of the grasses should be plentiful. Meadow hay is long, the stems rather hard, though in indifferent samples they may be soft. Compared with upland, it is coarser, darker in colour, and the aroma stronger, but this generally depends upon its preparation; the taste, owing to the coarseness of some of the grasses, is not so sweet. It generally contains a number of other plants besides the grasses.

It may be mentioned that the water-meadow hay is hard, long, coarse, and tasteless, without aroma, and full of water-plants. It is a very poor feeding material.

The value of hay depends much upon the mode of growth and the time at which it is cut, as well as the way in which it is preserved.

That made from grasses growing in sheltered places - as under trees and hedges - is insipid, and little worth as food; and all hay cut too late - after it has seeded - is less nutritious than when cut at the proper time.

The best hay is one year old, of a rather greenish tint, firm and long, clean, sweet to the taste, and of a pleasant characteristic odour. An infusion from it (hay tea) should be of a good dark colour; in the truss, flowers are found in it which still retain more or less of their tint. A large variety of good grasses are contained in it, and an abundance of flowering-heads.

Hay of medium quality, if old, is tasteless, brittle, and dusty; or if affected in quality from other causes, is short and fine, deficient in variety of grasses; or short, coarse, and dark in colour, odourless, taste perhaps pungent, and weeds sometimes present.

Hay of bad quality is mouldy, brittle, bad-smelling, perhaps dark-brown in colour, and innutritious. If composed of water-meadow grasses, these are seen in abundance, giving a great coarseness to the hay, which is deficient in colour and aroma.

Hay of medium and of bad quality are often found together, but they should be considered as distinct, as there is a hay of medium quality which, though unsuited for hard-worked or valuable animals, is yet useful for a certain class of horse, as it does not contain anything injurious, but simply, either through a bad season, bad sowing, or being a second crop, is destitute of the nutriment contained in the best quality, having none of those hurtful properties, however, found in bad hay. Again, hay originally of the best quality will, if kept too long, lose much of its nourishment, and become second-class forage.

Hay when less than one year old is termed new, and though horses like new hay, experience has shown that it is not good for feeding purposes, being likely to cause purging and abdominal pain; indeed, it is considered as innutritious. If it must be used, it should be given only in small quantities, and mixed, if possible, with old hay. It is preferable to give overripe, or even slightly weathered, hay, rather than that which is green and juicy.

Old hay is so called after its first year, and it generally retains its full nutritive properties for one year more; but, as a general rule, hay deteriorates and becomes dry after being stacked longer than eighteen months. Exceptionally, however, when grown upon good soil, mown, and gathered under favourable conditions, it is often after that age more nutritious than the succeeding year's crop.

New hay is distinguished from old by its green colour, more powerful aroma, the fibres containing sap, particularly at the joints, and by its being softer than old hay, which enables it to undergo more twisting without breaking. A truss of old hay, for the same weight as a truss of new - 56 lbs. - is less in bulk, owing to the amount of consolidation which has taken place in the rick.

The second or third cutting of hay is termed the "aftermath." It is greener than the first crop, softer, contains weeds and roots, no flowering heads, and the aroma is less marked than in good hay, even if well got; but badly harvested it is entirely destitute of perfume; owing to the lateness of the crop and the amount of moisture it contains, it is very difficult to harvest properly; as a rule it is only fit for cattle. When the grass is cut, it should remain in the field as short a time as possible; as if left in the sun too long it loses its colour and flavour, and becomes dried up; the difference of an hour on a hot day is said to occasion a loss of fifteen to twenty per cent. in the hay. If exposed to rain, much of its valuable nutriment is washed out of it. The peculiar aroma of hay is due to a volatile compound, some say to the sweet-scented vernal grass; in badly saved hay this aroma is destroyed.

In England the greatest care is exercised to preserve the colour and aroma, and this is secured by repeated turning and rapid drying; in Scotland, where little natural hay is made (that principally produced being from clover and rye grass), less turning is done, the crop is allowed to remain a number of days on the ground, and when gathered it does not ferment. Consequently, Scotch hay bears an indifferent name. For the same reasons, Irish hay is poor in quality; even more so than the Scotch, being left a longer time in the fields.

When hay is stacked in large quantity, it undergoes a certain amount of "heating," or fermentation, which improves its flavour and nutritive qualities; but if this heating is carried beyond a certain point, it causes damage. Hay ricked in a damp or wet state does not heat, but becomes mouldy and rotten. A rick should remain untouched for one year.

Hay may be badly harvested, dusty, mow-burnt, mouldy, or musty. In badly harvested hay the damage may be slight, caused by a shower of rain; or the hay may be bleached, sapless, and deficient in aroma, the result of being exposed to bad weather. When slightly damaged, such hay may be given as food; but when affected to any extent, it is only fit for bedding. Hay is made dusty from exposure to bad weather, or to the sun, or it may be due to decay. "Mow-burnt" hay is the result of undue fermentation in the stack, its colour being changed from brown to a very dark brown, almost black, the hay itself being dry and brittle, with a very pungent taste and powerful odour. When only slightly mow-burnt, horses do not dislike it, as it is sweet, owing to its containing a large amount of sugar, while the aroma is pleasant; but when badly burned, the sugar has become converted into acetic acid, has to a large extent lost its nutritious properties, and causes derangement of the digestion. Horses soon become tired of mow-burnt hay, which acts as a diuretic, and if continued for any time produces excessive thirst, loss of condition, listlessness and weakness, and the animal is in a condition to contract serious disease. " Musty " hay is that which has been exposed to wet and damp, either in the rick or before being stacked; mould is more or less abundant on it, the odour is unpleasant, and it has a bitter taste. It should never be given as food if possible, as it is liable to produce disease; if it must be given, it should be in small quantities, after being dressed with a solution of common salt, or it should be exposed to steam at a high temperature.

The artificial grasses which are made into hay are chiefly red and white clover; Swedish, Italian, and yellow clover; vetches, lucerne, and sainfoin. When these artificial grasses are converted into hay, the proportion of albuminoids per cent. is nearly equal to that of oats, and much greater than in the natural grasses, though they contain less fats, carbo-hydrates, and phosphates; the flesh-producing elements in clover are given as 13.52 for clover and 8.44 for meadow hay. The artificial grasses are too rich to be given alone in large quantity, as "broken wind " and indigestion, as well as liver disease, have been attributed to them. They should therefore be given in small quantity, or mixed with hay. Owing to the amount of moisture in clover, there is great difficulty in converting it into hay; consequently, it is liable to become mouldy and rank, and therefore liable to produce disease of the bowels, etc. The trefoils are said to contain a very active principle very irritating to the kidneys. The amount of artificial forage which may be given to horses with safety will vary according to circumstances; in the green state, it should be used sparingly, especially with horses which are brought on to it for the first time, as it is liable to undergo fermentation in the intestines, and cause extreme distension. In the form of hay, owing to its highly stimulating qualities, a sparing use of it should be observed; one-third of this forage to two-thirds hay would be a judicious mixture for ordinary use for horses not performing hard work. Lucerne is a valuable food, when green, for sick horses; it should, however, be half dried in the sun before use, if possible. When made into good hay, it is very good feeding, mixed with the ordinary ration.