FEEDING THE DAIRY COW

Hawke's Bay Herald-Tribune, Volume 81, Issue 52, 24 November 1937, Page 13

FEEDING THE DAIRY COW

Essential Requirements o£ a Ration THEORY AND PRACTICE Most dairy farmers, including all the successful ones, understand. the practice of feeding the dairy cow . They xealise, too, that behind every sound practice in feeding there is a thepry— frequently oue that has been substantiated by oarefully conducted trials arid experiments, as well as by practical experience, but few of them have taken the trouble to study fhe theory of this alljmportant operation. The more intricate problems involved in the science of feeding the dairy cow are things that might well be left to the scientists, who are specialising in. their solution but the simpler problems of feeding frequently can be solved by the practical dairy farmer, provided he has at least a little knowledge of the theory of feeding and of the reasons on which current feeding practices are based. At some timo or other we have all likened the dairy cow to a machine, and our explantion of feeding theories will be simplified if, once again, we think of the production of milk as a manufacturing process, in which the raw materiaP contained in the cow's ration is converted into the finished produce, milk, by that highly efficient aiachine, the dairy cow. In addition, this conception of milk production should serve to emphasise the need for proper care of the animal, and for int'elligent aelection of her feed.. Feed, Water and Air._ If our machine, the dairy cow, is to be maintained in full productivity, it must have a sufficient supply of good feed, ample pure water and plenty of fresh air. From these sources the dairy cow must obtain the energy required for maintaining the .physical and chemical, voluntary and involuntary artivities in which she is continually ehgaged. From these sources also she must obtain all the raw material needed for replenishing the body tissue constantly being consumed in life processes, for the production of milk and of offspring and for her own growth. And, just as the mechanic finds it necessary to know the requirements of his machine and of the raw material he is using, so must the dairy farmer know something of the requirements of the dairy cow and of the character and properties of the feeds by which those reqquirements may be met. Like the machine, the animal body is contiDually wearing out. ' To make up this waste a certain amount oi repair material is necessary. This material can be supplied only by the protein in the food. If the animal requires also energy to do its " work, whether thatjwork be the actual physical labour required to transport itself from place to jplace, or the work of producing cnilk. This energy is derived partly from the p'Yotein in the food, but mainly from the carbohydrates and fat that make up the main part. of the ordinary ration. "We find then that there are three main *nutr jtive compounds that make up the ration. The first of these, the protein, is the essential body building material in the feed, since it is the only part that contains the nitrogenous compounds needed for the repair and development of the body tiesues, or for production of the nitrogenous substances in the milk or in the offspring. The carbohydrates and fats do not contain nitrogen and, therefore, cannot replace proteins in these essential tasks. •The proportion of' protein contained in any feeding stuff can be determined only by chemical analysis, but common feeds, which are comparatively rich in protein include all the legumes, most grains and meals, such as those made from linseed and cotton seed. ' Carbohydrates land Fats. The carbohydrates and fats are compounds of carbon, hydrogen and oxygen, without nitrogen, and are the main_ source from which the animal body derives the energy necessary for its vital activities and for production. Carbohydrates include starch, sugar, and the digestible forms of fibre, and form by far the larger part of the nutriment contained in all common feeds derived from grains and grasses. The fats occur principally in feeds derived from seeds, such as linseed oil meal. Almost any Tation will contain a small amount of fat — usually sufficient for the particular fat requirements of the animal. A ration too rich in fats is liable to cause digestive troubles and probably loss of appetite. Each of the three digestible nutrients found in the ration may be used by the body for energy, but for this purpose 11b. of fat is equal to 2i lb. of carbohdydrate Or 2J1L. of protein. Thus protein and carbohydrate have the same energy producing value, but carbohwdrate cannot be substituted for protein in repairing waste tissue or in forming the protein content of the offspring or of the calf. If the Tation supplies «jore nutriment than is required for furn>iing energy and building material tlie surplus will be converted into body fat. . Balanced nation. Sinee protein normally is tlio most expensive oonstituent of the Tation, it follows that a desirable ration is onr containing just the right proportion of that particular material. In othei WOrdS, we inust s'cek a lialanc'ed ration — one in which digestible protein carboh^drates- aad- fat- are^ aresent- ia1 ths

propqrtions and quantities needed tq meet the requirements of the animal. Such a ration will give adcquate nourishment to the animal without waste. Obviously, a balanced ration must contain ,both protein and carbohydrates. The actual proportion will depend on the purpose for which the ration ia used. For maintenance only, a suitable ration would be one containing 101b. of carbohydrates to eaeh 11b. of protein. This would give a "wide" nutritive ration of 1:10. For a milking cow a ration with a "narrower" nutritive ration of, say, 1:5 would be necessary. In addition to protein, carbohydrates and fats, the animal 's ration must cou. tain certain minerals. Those minerals most likely to be deficient in the ordinary ration are common salt, lime and phosphorus, which are found in comparatively lavge amounts in the bones, blood and nerve tissues of the body. Milk contains a good deal .of calciujn or lime, and it has ,been estimated that in each galJon of milk producea the dairy cow utib'ses approximately cwothirds of an ounce of salt. Salt is normally supplied as a lick, and most balanced rations which are made up of a variety of feeds will contain sufficient lime and phosphorus. In certain circumstances, howeyer, the feeding of a specially compounded mineral lick may be advisable, white the practice ^of feeding lucerne hay to dry cows is to be commended, since cfomng heavy milk production, the cow may use more lime than can be assimilated from her ration, and to miake iip the deficit s,he> will draw on the supply stored in her bones. Luce'rne is rich in lime, and will help to restore the position. Compounding the Ration. In actually compounding the Tation for a dairy cow, several considerationa must be kept in mind, the most important being the cost of ingredients, bulk, palatability, variety, succulenco, the effecto f the system of the animal and the balance of nutrients. The flrst of these needs no further comment. As far as bulk in the ration is conce'rned, it must be remembered that the cow has a particularly large digestive tract, and if the ration is not sufficiently .bulky it will not be thoroughly digested. A palatable ration is necessary to induce sufficient consumption to support liberal production, and variety in feeds is desirable for the same reason. The addition to the ration of a succulent feed increases the palatability, jncreases consumption and has a cooling and laxative effect on the digestive system. Naturally, the effect of the ration on the system of the animal must be watched, and, if necessary, a more laxative feed should be included.