An animal, to be fully fed and satisfied, requires a quantity of food in proportion to its live weight. No feed is complete that does not contain a sufficient amount of nutritive elements; hay, for example, being more nutritive than straw, and grains than roots. The food, too, must possess a bulk sufficient to fill up to a certain degree the organs of digestion of the stomach; and, to receive the full benefit of its food, the animal must be wholly satisfied--since, if the stomach is not sufficiently distended, the food cannot be properly digested, and of course many of the nutritive principles which it contains cannot be perfectly assimilated. An animal regularly fed eats till it is satisfied, and no more than is requisite. A part of the nutritive elements in hay and other forage plants is needed to keep an animal on its feet--that is, to keep up its condition--and if the nutrition of its food is insufficient for this, the weight decreases, and if it is more than sufficient the weight increases, or else this excess is consumed in the production of milk or in labor. About one sixtieth of their live weight in hay, or its equivalent, will keep horned cattle on their feet; but, in order to be completely nourished, they require about one thirtieth in dry substances, and four thirtieths in water, or other liquid contained in their food. The excess of nutritive food over and above what is necessary to sustain life will go, in milch cows, generally to the production of milk, or to the growth of the foetus, but not in all cows to an equal extent; the tendency to the secretion of milk being much more developed in some than in others. With regard, however, to the consumption of food in proportion to the live weight of the animal, it must be taken, in common with all general principles, with some qualifications. The proportion is probably not uniform as applied to all breeds indiscriminately, though it may be more so as applied to animals of the same breed. The idea of some celebrated stock-raisers has been that the quantity of food required depends much upon the shape of the barrel; and it is well known that an animal of a close, compact, well-rounded barrel, will consume less than one of an opposite make.