448 DISEASES OF CATTLE. 



AMOUNT OP NUTRIENTS REQUIRED BY OUR FARM ANIMALS. 



The next step in our study is to ascertain the amount of the several 

 constituents in feeding materials required by different farm animals 

 under varying conditions for maintenance, growth, and fattening. 

 Since the weights of our animals vary according to age and breed it is 

 well to take some simple standard of weight, and for convenience it has 

 been placed at a thousand pounds. The needs of growing animals dif- 

 fer from those that are mature, and the requirements of work animals 

 are not the same as those at rest or taking on fat. In Table II is sum- 

 marized the amount of digestible nutrients required by a thousand 

 pounds, live weight, of farm animals. 



To study this table let us take the first case that of an ox at rest 

 in his stall. This ox is supposed to weigh 1,000 pounds, and to be kept 

 perfectly comfortable as to temperatiire and environment, and to do no 

 work, neither gaining nor losing in weight. The amount of food 

 required under these conditions will be the minimum for such an animal? 

 of course. It will be found when we have furnished this ox with the 

 digestible nutrients required that the total organic substance, which is 

 the weight of the fodder, less the water and ash it contains, will amount 

 to 17.5 pounds. Every beat of the heart, every respiration, the tension 

 of the muscles while standing, all mean wear and destruction of mus- 

 cular tissue. Indeed, every manifestation of life means the consump- 

 tion of food to repair the waste of some portion of the body. The 

 Germans have held that 0.7 of a pound of crude protein is necessary to 

 make good this loss. For warming the body and running its machin- 

 ery, if we may so speak, there are required 8 pounds of digestible car- 

 bohydrates and 0.15 pounds of ether extract. Adding the digestible 

 protein, carbohydrates, and ether extract together, we get a total of 

 8.85 pounds of total nutritive substance. If we multiply the digestible 

 ether extract by 2.2 and add it to the digestible carbohydrates the sum 

 is 8.33, which, divided by 0.7, gives a quotient of 12 in round numbers. 

 That is, for every 1 pound of crude protein required by the ox, he needs 

 12 pounds of digestible carbohydrates or their equivalents in fat. 

 Investigations by several American experimenters have shown that the 

 amount of nutrients stated by the Germans as only sufficient to maintain 

 a thousand-pound ox is more than sufficient for that purpose under our 

 conditions, and that the ox will make a small gain therefrom. Our 

 Avork, however, has not progressed far enough to reconstruct even this 

 portion of the table, so that we shall have to let it stand as stated by 

 the Germans. 



In the same table we learn that the ox heavily worked requires 2.4 

 pounds of digestible protein per day, or three times as much as when 

 at rest. We are not surprised at this, for when performing labor the 

 muscles must be worn down much more rapidly than when an animal 

 is idle. A milch cow of the same weight requires more protein and 



