Computing Rations for Farm Animals 1573 



computing a ration 



The nutritive ratio 



Investigators and practical feeders alike have found that there is a 

 certain relation between the protein and the carbohydrates and fat in 

 the best rations. This relation is called the " nutritive ratio." The 

 ratio is always expressed as the amount of carbohydrates and fat that 

 there is in a given food or ration compared with one pound of protein. 

 In order to find the second term of the nutritive ratio in any given food 

 or ration, multiply the digestible fat by 2 \ for the reason given on page 7 ; 

 add the digestible fiber and digestible nitrogen-free extract; and divide 

 the result by the digestible protein. For example, the nutritive ratio 

 of fodder corn is found by Table 1 to be 1:12.8. This means that in 

 fodder corn the relation of the protein to the carbohydrates and fat is 

 as 1 : 12.8; or, that fodder corn has twelve and eight tenths times as much 

 carbohydrates and fat as protein. 



The relation of the protein to the carbohydrates and fat has been 

 calculated in each of the foods in Table 3 and will aid in the choice of 

 foods to properly balance a ration. A knowledge of the nutritive ratio 

 of a food serves to tell at a glance whether that food is high or low in 

 protein. 



The calculation of the nutritive ratio of a ration as a whole serves as 

 a check on the ration, to denote whether it is suited for the purpose in- 

 tended, as will be shown later. 



A food or ration having a nutritive ratio of less than 1 : 6 is spoken of 

 as having a " narrow " nutritive ratio; if the ratio is above 1 : 6 the ration 

 or food is said to have a " wide " nutritive ratio. These terms are purely 

 relative, but serve in a rough way to distinguish the different kinds of 

 foods and rations. 



Feeding standards 



The requirements of animals as to amount of necessary nutrients for 

 such purposes as milk production, beef production, labor production, and 

 the like, as well as the relation between these nutrients, have been the 

 subject of much inquiry. Investigators have sought to put those require- 

 ments into definite form. They have given to this table of requirements 

 the name " feeding standards." The standards are merely a statement 

 of the necessary amount of nutriment required by an animal for a given 

 purpose for a certain length of time. They are based on the requirements 

 for 1, coo pounds live weight in 24 hours. The requirements are usually 

 stated in terms of dry matter, digestible protein, digestible carbohydrates 

 (fiber plus nitrogen-free extract), and digestible fat. The nutritive ratio 

 for the given purpose for which the animal is to be fed is stated. With 



a view of shortening the computation of the ration as much as possible, 

 109 



