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Show Hlff By E. W. ALLEN, Assistant Director vt the Office of Experiment Stations, United States Department of Agriculture. THE feeding of fnrm nnlmnls, like the use of fertilizers for crops, rests upon quite well dellned general principles. Tlio materials of the body are continually breaking down and being consumed, and to keep the animal In a healthy and vigorous condition there must be a constant supply of new material, if, in addition to repairing the wastes of the system and furnishing It with heat and energy, growth Is to bo made (as in the case of Immature animals) or milk, secreted an additional supply of food is required. To supply food in the right proportion to meet the various vari-ous requirements of the animal without with-out a waste of food nutrients constl- VnaMNnaMMMMMMIMMHaMMMMMMMMMWR Photo by Lonjj Island experiment station ' . HOTOIl FAUSI WAOON ritibnS'a THE HII.O. tutes scientific feeding, 'it Is by carefully care-fully studying the composition of feeding feed-ing stuffs, the proportion in which they are digested by different animals and under different conditions and the requirement re-quirement of animals for the various food nlitrients when at rest. nVwork, giving milk, produclug wool, mutton, beef, pork, etc., that the principles of feeding have been worked out In applying ap-plying these principles In practice the cost and special adaptations of different differ-ent feeding stuffs must of course be taken into account. The animal body 4s made up mainly of four classes of substance ter, ash or mineral ingredients, fat and nitrogenous ni-trogenous matters. Water constitutes from 40 to CO per cent of the body and Is an essential part Prom 2 to 5 per cqnt of the weight of the body Is ash. This occurs mainly In the bones. Tlio fat varies greatly with the condition-1 of the animal, but seldom falls below 0 per cent or rises above 30 per cent1 The nitrogenous material or protein ' includes all of the materials containing contain-ing nitrogen. All those outside this group are nitrogen free, or nonnltrog-' enous. Nitrogen occurs In plants and animals In various compounds grouped group-ed under the general uame of protein. The flesh, skin, bones, muscles, Internal Inter-nal organs, brain and nerves In short, nil of the working machinery of the body arc composed' very largely of protein. The albuminoids are a class of compounds included under protein. The food of herbivorous animals con-' tains Hi.' 4:irae four groups of sub-' stances fotiMl In, the body viz, water, ash. protein (nitrogenous materials) and fat and. In addition to these, a class of materials called carbohydrates, j dellned below Howewr dry a feeding stuff may ap-' pear to Jie. it always contains a con-! Mdcrnhlc amount of water The amount moy be only from eight to lif-' teen pounds ppr IOC pounds of mate-1 rial, as in hay, straw or grain, but in green corn fodder and slinge It amounts to nearly eighty pounds and hi some roots to ninety pounds. This water, although it may odd to the palatahlllty of a food, is of no more benefit to the animal thnn water which It drinks. Ash Is what Is left when the combustible com-bustible part of a feeding stuff is burn-td burn-td away. It consists chiefly of lime, mngncsia, potash, soda. Iron, chlorine and carbonic, sulphuric and phosphoric acids and Is used largely In making bones. From the ash constituents of the food the digestive organs" of the. animal select those which the, nnlraaP needs, and the rest Is voided in tho manure. As a general rule, ratloni composed of a variety of nutritious foods contain stilliclont ash to supply tho requirements of the body. Corn, however. Is poor in nsh, and when fed exleuslvely to growing animals, llkt pigs, it may bo necessary to add to II j aome nsn material,,. nawood as- charcoal or boueuieal. " ! . Fat or tho mliterlal 'ffhMi in nnlily-. nnlily-. els Is dissolved from .oN feeding stuff, by ether Includes, besides real fats, wax, the green volutin, tn '..r , plants, etc. For this reas i-t'u-r dxtruct Is usually deslgna , .. t:it The fat of food Is either ' i ' i the body as fat or burned t. M.nNN heat and energy. Curbohydrutes trc usiia'Iv .Hvldel Into two groups: (1) nltio-i-n fn tract, Including starch. s fir. i-min and the like, and (2VcIIuum- r fiber, tho essential constituent of the walls of vegetable cells. Cotton liitcr and wood pulp are nearly pure lellulosa Coarse fodders, like hay and straw, contain a large proportion of fiber, while most grains contain little liber, but ttnfrlch In starch, HU,'iir, etc. (nitrogen (ni-trogen free extract.) The carbohydrates carbohy-drates form tho largest part of nil vegetable veg-etable Tooda. They are not permanently permanent-ly stored up ns such In the animal body, but are elthor Btorcd up as fat or burned In 'the system to produce hent and energy. They are one of tho principal sources of animal fat. Protein (or nitrogenous materials) Is the name of a group of materials containing con-taining ultrogen. Protein materials are often designated as "Hosh formers," form-ers," because they furnish tho mate , rials for tlio lean flesh, but they also ; enter largely Into tho composltloiftof blood, skin, muscles, tendons, nerves, hair, horns, wool, tho casein and albumen albu-men of milk, etc. For the formation of these materials protein is absolutely i Indispensable. No substances free j from nitrogen cnu bo worked over Into protein or till tho place of protein. Under certain conditions it is believed protein may be a source of fat In tho body, and finally it may he burned, like the carbohydrates and fat, yielding hent and energy. The value of tho fat for producing hent Is nearly two and a half times that of carbohydrates or protein. Tho sources of fat in the body are the fat, carbohydrates and probably the protein pro-tein of the food, and tho excluslvo source of protein in tho body Is tho protein In tho food. These groups of food materials are termed uutrlcnts. To a certain extent at least tho nutrients nu-trients mny replace one another, although, al-though, ns stated above, no other nutrient nu-trient can take the place of protein. Tho fat and carbohydrates perform similar functions, and, to a largo ex-,tent, ex-,tent, carbohydrate materials mny re-ploco re-ploco fat In tho food, even when a large fat production is demanded of the nulmnl, as in the caso of tho cow. The composition of feeding stuffs, or the proportion In which the nutrients occur, is dctormiBed,by Chemical analysis. analy-sis. Only a portion of the nutrients is of direct uso to tho animal -I. e only that digested. A 'part of tho food Is dissolved and otherwise altered by tho Juices of the mouth, stomnch n'nd intestines in-testines absorbed from the alimentary canal, and lu the form of chyle pnsso3 Into the blood nnd finally serves to nourish nnd sustain tho body. Tlio other portion Is excreted. As the rates of digestibility are not constant for different foods and as only tho digestible portion Is of any nutritlvo uso to tlio animal, it Is essential essen-tial to know In tho caso of each feeding feed-ing stuff what part of Its protein, fat and carbohydrates (tho total quantity of which is shown by analysis) Is actually digested by tho animal. This Ib determined by digestion experiments experi-ments with animals, and to secure approximately ap-proximately accurate llgures tho trials are repeated with a large number of animals and under various conditions. Tlio digestibility of such coarse fodders fod-ders as straw, coarse hay, etc.. Is relatively rela-tively low. The digestibility, like tho composition, varies somewhat for tho same kind of feeding stuff grown under un-der different conditions nnd fed to different dif-ferent animals. Calculations have been- nindo of the amounts of digestible protein, fat and carbohydrates contained in 100 pounds each of a larjre number of more commonly com-monly used feeding stuffs. They are tho figures which the farmer has to consult to find the npproxlmnto food value of a material lu selecting hl3 feeding stuffs or making up n ration. Tlioy nro available in various publications. publica-tions. Including those' of the United States department of agriculture. For oxamplo, in 100 pounds of greon corn fodder with nn uvorago amount of dry matter (27.7 pounds) thero nro contained approximately 1.10 pounds of dlgestlblo protoln (materials containing con-taining nitrogen), 12.8 pounds of digestible di-gestible enrbohydrates (starch, sugar, fiber, etc.) nnd 0.87 pounds of dlgestlblo dlgestl-blo fat, and these mnterinlB when consumed in the body will yield 20,070 calories, or units, of hent, furnlshlMg energy for work and bodily bent. An ox standing In tho stall requires loss food nutrients than one which is worked hard every day. in standing stand-ing In the barn It Btlll required some protein, fat and carbohydrates to per-iform per-iform tho necessary functions of tho body to maintain hdat in winter, to grow a new cout of lialr etc. But If It if? fed the same ration as when working hnrd the tendency is to get fnt or waste the food. Tho cow requires not only mntorlols for maintenance, hut must nlso hijve protein, fnt nnd carbohydrates to make nillk front Tho milk contains "water, 'nt Itt-otjln"7icu4ojn..oi l i nnd asli. and fhoaViirg all fcmic ! the constituents of the food tf lu sulllclent protein, fat and cirlwdH'- . drates are contained In the food drun her the cow supplies thN 'lellcleni'y for a time by drawing on her own body and gradually beulns toN shrink in quantity or quality of milk, or both. The stingy feeder cheats himself ns well as the cow She mny suffer from hunger, although her hell Is full of nwale hay. but she also bfcouus poor , nnd docs not yield the milk and butter she should. |