230 THE COMMON COLICS OF THE HORSE 



In comparing the feeding value of different foods 

 (apart from their ' balance 'i), it is useful to calculate the 

 food units which are contained in them. In calculating 

 the food units, it is assumed that the moisture, fibre, and 

 ash are of no feeding value. Experiments have shown 

 that fats and albuminoids produce (practically) two and 

 a half times the heat that carbohydrates do ; therefore, 

 to obtain the food units, .we add the percentages of fat 

 and nitrogenous substances, multiply the sum by 2J, and 

 add the percentage of carbohydrates. The result is the 

 number of food units. 



As an example, let us calculate the food units of oats and 

 beans from the composition given in the previous table : 



Oats. Beans. 



Fat . - - . 4-81 166 



Nitrogenous substances - 13' 13 26-25 



27-91 

 Multiply by - - - 2| 2| 



69-77 



Add carbohydrates - 55-45 47 36 



Food units - - - 100-30 117*13 



It will thus be seen that, if all were digested, the 

 feeding value of oats and beans is in the ratio of 

 oats 100 and beans 117 — that is to say, beans have 

 about one sixth more feeding value than oats ; or, 

 6 pounds of beans will produce as much heat and energy 

 as 7 pounds of oats. 



As these calculations of food units are taken on the 

 composition of the food, it follows that the whole of the 

 constituents are included, whether digested or passed 

 out as manure, their use both as foods and fertiUzers 

 being taken into account, for, with ordinary care, what 

 is not used as food is utilized as manure. 



Digestive Coefficients of Foods. — The composition 



^ I.e., the ratio of nitrogenous to non-nitrogenous foods. 



