Dairy is a word used in speaking of a number of cows kept for milking purposes, or to indicate the buildings in which Milk (q.v.) is sold or manufactured into Cheese (q.v.) or Butter (q.v.). The byre or cow-house should be connected by a covered way with the milk-house proper, and the arrangements for ventilation made so perfect that it should not be possible to detect in the vicinity of the milk any smell from the cows, pigs, or other source. The milk-house should on no pretext be made a common storeroom for meat, game, onions, or any material which will taint the air and then the milk and the cheese or butter, as the case may be. The first essential in a dairy is the absolute cleanliness not only of the floors and walls of the building, but of all its furnishings. This is secured by daily washing and by the scalding or steaming of all vessels or implements which come in contact with milk or its products; the object being to destroy the microbes which live and multiply in milk and bring about its acidity and decay. The thermometer in the dairy should stand at 55° F. in summer, and 60° F. in winter. At temperatures higher than these milk is liable to spoil, owing to the greater activity of the above-mentioned germs; many degrees below this it gets chilled, and will not manipulate satisfactorily. An abundant supply of pure water is necessary, and means for boiling water must also be provided, not only to secure scalding water for washing, but to raise, when necessary, the temperature of the products of milk during manufacture, or maintain a suitably high temperature in the air of the cheese-room or the milk-house. A small steam or gas engine is frequently employed in a dairy conducted on a large scale, to supply the power necessary for a centrifugal Cream Separator (q.v.), also for churning whole milk or cream, and at times for driving the compressed-air refrigerator. The latter is used to lower the temperature of vaults in which fresh, summer-made butter is stored until the winter season, when the prices for good 'grass' butter are high. As the cost of the necessary machinery is considerable, the method can only be made to pay when the business is extensive.
Dairying has developed much within recent years. The growing demand for milk in large towns has increased the volume of the milk-trade, and modified the system of management. Summer dairying, while suitable for the making of cheese, and so far for butter also, must be supplemented by winter dairying to keep up the supply of milk and fresh butter throughout the year. For summer dairying it is usually arranged that the cows calve during March, April, and May, so that they go to pasture when they are coming to the period at which, with a proper supply of succulent food and suitable surroundings, they should develop their greatest yield of milk. They lie out day and night, and have the whole summer and early autumn before them—the period in which grass, the most natural food of a cow, is most abundant, best, and cheapest. In some instances the grass is supplemented by 2 or 3 lb. a day of cotton-seed or other cake, and when the grass begins to fail in autumn, some variety of green food, as cabbages, rape, vetches, &c. As frost begins to appear the cows are housed at night, and in spite of liberal and careful feeding, fall off in their yield of milk. Nevertheless, it is the better practice to house them in good time, because they keep in better condition during winter than if left out too long, and for the few remaining weeks of the milking period they give a larger average return. All naturally 'dry off,' some more rapidly than others. Milking should be stopped abruptly at the end of the year—experience points to this being the best and simplest method of drying off cows at this season. After two or three months of rest, the cows calve, and this goes on year by year from the age of two or three (depending upon size and condition) until ten years old, when all should, without exception, be replaced by heifers. A ring appears on the horn to mark each year after the third year, and by this the age can be determined.
Where winter dairying is also practised, the cows are made to calve at all times of the year, so that a number come in possibly every week, to replace others that have ceased to milk satisfactorily. The temperature of the cow-house has to be maintained at such a high point, to keep up the full flow of milk during winter, and the feeding is made so forcing and unnatural that the constitutions of cows would show the effects of this high-pressure system if they were kept to calve another year. In consequence, few farmers who adopt this system of management retain their cows more than one milking period. They shut them in the house both summer and winter, and give a full supply of food all the while, to maintain their condition. Some send them to auction as soon as the yield of milk falls to the net cost of its production. Others attempt to feed the cows after this until they put on flesh, so that they command a higher total price and a higher rate per stone in the fat market than ordinary milking cows. Unquestionably the system of changing cows after one milking period pays farmers who are favourably situated for the disposal of milk to private families, better than keeping them for a number of years and 'bringing them round' to calve each season; yet there is one serious drawback as regards the suspension of the improvement of dairy cattle, by neglecting the selection of calves for rearing from the best milking mothers. The system is only possible, without doing serious injury to the breeds of cattle, because it is not general throughout the country, but confined to dairies supplying milk to large centres of population.
Eight to ten cows is a sufficient number for each milker, and the operation should be performed as quietly and as expeditiously as possible. Men are usually employed in England, and women in Scotland. When cows give a large flow of milk, or when it is wanted for town consumption, milking is done thrice daily; but in the great majority of cases throughout the country it is only performed morning and evening. Heavy milking cows consume a large quantity of water, which should be supplied to them at least twice daily. Cows not in milk are often allowed to drink only once a day, though it would be better to let them do so twice. To offer tepid water to a cow immediately after calving is an unnatural and altogether unnecessary precaution; she should have cold, but not iced, water in small quantities, and given frequently until she is satisfied. Cows consuming a large amount of sloppy food and roots do not require much water.
It is important that the water should be pure and clean. Outbreaks of typhoid fever among children have been traced to cows drinking water contaminated with the germs of this disease. Though sewage irrigation grass is extensively used, under the 'soiling' system, by cowfeeders near to towns (Edinburgh, for example), no injurious results have been traced to this practice. Irrigation grass has been largely superseded within recent years by supplies of better quality got from immense crops of Italian ryegrass (Lolium italicum), grown without irrigation by means of heavy and repeated dressings of nitrate of soda. In no place can this system be seen to greater perfection than around Edinburgh. In some parts clover and vetches take the place of ryegrass. Succulent food is essential for the production of large returns of milk. As the grass season ends in October, the succulent portion of food may be derived from brewers' and distillers' grains (1 bushel per day being a full allowance for a large cow), and from turnips—a favourite variety at present being the Fosterton hybrid. Turnips, when given in excessive quantities, produce an objectionable taste in the milk and butter, but as an ingredient in a liberal and well-balanced diet they may be used with impunity, where milk is the product wanted. Swedes and mangels are not so liable as common turnips to taint cow products, and as they keep well when stored, they are reserved for use during the winter and spring months. Cows in full milk require a daily allowance of perhaps 5 to 8 lb. of concentrated food—a mixture of various farinaceous meals and oil-seed cakes along with bran, which acts as a corrective as well as a food substance. Bean meal is prominent among the meals for encouraging a flow of rich milk and at the same time maintaining the condition of the cow. Turnips, unless liberally supplemented, are liable to reduce the condition. The ingredients in the food mixture should be determined by their market prices from time to time. There is a decided advantage in giving a mixed food, as compared with one variety, provided a proper proportion is secured between the albuminoids and the carbohydrates—one to five is a good ordinary average to aim at under ordinary circumstances, having estimated oil as equivalent to two and a half times its weight of starch. Not only must the proportion of the components of a food mixture be adjusted, but the total bulk of the food must be great enough to distend the stomach sufficiently to promote healthy action in the digestive system. About 30 lb. of dry food substance is a good allowance for a healthy milking cow of one of our large breeds. If that were given entirely in the form of concentrated food, such as meal and cake, the animal could not chew the cud, and impaction of the rumen would result. The practice of chaffing straw into very short lengths is associated with the same danger. Dry fodder, more especially straw, is vastly improved for milk cows by cooking—either steaming it, or throwing warm water over it, and covering it up for a few hours. In spring, before the grass comes, the flow of milk in newly-calved cows is often largely developed and maintained by treating hay in this fashion, and supplying them with the hay tea and the solid residue mixed with meal. When very large quantities of concentrated food are used, it is safer to add to the daily allowance of each cow from 1 to 2 lb. of molasses, which supplies not only a valuable ingredient of food, but maintains a healthy action in the organs of digestion. Without some such precaution the percentages of ailments and deaths, in the case of cows kept under a high-pressure system of feeding, are likely to be considerably above an average. Epsom salts should never be given to a cow in milk, as they permanently reduce the yield for the season; 8 to 10 lb. of warm treacle is more rapid in its action, safe, and free from injurious after-consequences. Bought concentrated food has another function than the above to perform. Its ash ingredients which pass away in the manure make good to the land the considerable loss of bone-earth and other valuable substances which are removed in dairy products—more especially milk. See CATTLE, BUTTER, CHEESE, MILK.