FEEDING EQUIPMENT 209 



The nutrients must first be reduced to the same value. The 

 fat in a feed is richer than the others in heat value. Fat has been 

 found to have an energy value of two and one-quarter times that 

 of carbohydrates, so that it is necessary, in order to reduce them 

 to the same value, to use this coefficient in the solution. Nutritive 

 ratio can be expressed in the following manner, by formula : Given 

 a ration containing 10 pounds protein, 30 pounds carbohydrates, 

 and 5 pounds fat. 



Nutritive ratio = 1 : 4.13 



Protein : carbohydrates + (fat X2. 25) 

 10 : 30 + (5X2.25) 



10 : 41.25 



1 : 4.13 



It will be noticed in the above calculation that the amount of 

 fat present was multiplied by 2.25. 



Potential Energy. It is often helpful to know the heat values 

 which the nutrients present in a ration will develop when consumed 

 by the birds. This capacity is expressed by the term " potential 

 energy." This means the measure of value in units of heat or 

 energy in the nutrients themselves. 



Potential energy is expressed in calories per ounce. A calory 

 is a unit of heat or energy. It is the amount of heat necessary to 

 raise one gram (about A of an ounce) of water one degree of 

 temperature on the centigrade thermometer. It is known that 

 one ounce of carbohydrates or of protein has a potential energy 

 of 116 calories, while one ounce of fat has a potential energy of 

 264 calories. In actual practice the energy value of any ration 

 may be quickly determined by using the following multiples : One 

 pound of protein or of carbohydrates will develop 1,860 calories, 

 and one pound of fat will develop 4,220 calories. 



Balanced Rations. It is possible by careful calculation to 

 approximately compound a ration which will contain a sufficient 

 amount of nutrients in the right proportion for the laying hen. 

 When this is done the ration is expressed as being balanced, or, 

 better, as being proportioned to meet the requirements of the indi- 

 vidual for combined maintenance and production. In actual prac- 

 tice it is possible to balance rations for only short intervals. The 

 ration as combined may leave nothing to be desired, yet the birds 

 exercise their power of selection, some individuals getting an en- 

 tirely different diet from others. Individual desires and inclina- 

 tions differ. The actual feeding practice should be to form an 



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