FOOD AND FEEDING 481 



of food. The fuel value means the amount of heat that is given out by 

 food in its combustion io the body. There is much less heat formed by 

 the combustion of food within the body — on account of losses in food 

 undigested and fermented in the bowels and escaping incompletely burned 

 in the urine — than would occur in food burned outside the body. The 

 heat or energy value of food is measured in calories or therms. A calory 

 is the quantity of heat necessary to raise 1 gram of water 1° C A 

 therm is the amount of heat required to raise 1 kilo, of water 1° C. 

 Tables based on the most elaborate experiments showing the actual 

 amount of fuel or energy value of foods, together with the amount of 

 digestible protein and dry matter contained in them, must be consulted 

 in calculating daily rations. 



Thus, for maintenance of animals of 1,000 lbs. ' live weight per 

 diem, it has been found that cattle require 0.5 lb. of digestible protein 

 and food of the energy value of 6.0 therms. Horses require 1.0 lb. 

 digestible protein and food of a fuel value equal to 7.0 therms. 



The daily food requirements of grown cattle are such that for each 

 pound of digestible protein there should be 8 to 10 lbs. of carbohydrates 

 and 20 to 30 lbs. of total dry matter. More important still, it has been 

 found that there are necessary — in addition to the maintenance require- 

 ments of cows — 0.05 lbs. of digestible protein and 0.3 therm in energy 

 value in the daily ration for each pound of milk produced. 



As a practical application of the foregoing, suppose that we com- 

 pute a ration for cows giving 25 lbs. of milk daily and weighing 850 lbs. 

 Consulting a table showing maintenance requirements, we find that 0.45 

 lb. of digestible protein and food of energy value of 5.6 therms are 

 necessary. Multiplying the additional requirements for each pound of 

 milk produced (as above) by 25, we find that 1.25 lbs. of protein and 

 7.5 therms are necessary for this milk yield — beside the maintenance 

 requirement. Adding the requirements for maintenance to those for 

 milk yield we get the total daily requirements for cows weighing 850 

 lbs. and yielding 25 lbs. of milk as follows : 



Digestible protein. Energy value. 

 Lbs. Therms. 



For maintenance 0.45 S.6 



For 25 lbs. of milk.: , 1.25 7.5 



1.70 13.10 



We shall now have to consult a table* showing the energy value, 

 proteid content, and dry matter in all ordinary fodders, and combine 

 them so that they shall possess in the daily ration 1.7 lbs. of digestible 

 protein, energy value of 13.10 therms, and dry matter equal to 20 to 

 30 lbs. 



The particular food stuffs must be selected so that they shall be 

 the cheapest in the locality in which the feeding is done. 



The mechanism of the animal body is always "running," and an 

 animal at rest ia like a motor car at a stand-still with the engine moving. 



»Armsby, Bull. 346 and 459, U. S. Dep't. Agric. 



Digitized by Microsoft® 



