184 Net Energij Values and Starch Values 



use it is not always easy, even for experts, to avoid misapprehension and 

 confusion of thought, as some striking instances in the recent literature 

 of the subject have shown. 



Misapprehensions regarding Starch Values. 



Kellner's starch value in its proper sense as just defined has been 

 mistakenly identified with two quite different conceptions. 



The first of these is the so-called "Carbohydrate equivalent" of the 

 digestible nutrients. By conventional methods we determine the amounts 

 of digestible protein, carbohydrates and fat contained in a feeding stufE 

 and by multiplying the fat by 2-25 or a similar factor and adding the 

 other two we compute the carbohydrate equivalent of the digested 

 substances, or the "Total nutrients." Thus for average American alfalfa 

 hay as reported by Henry and Morrison^ the computation is 



Digestible protein 10-6 per cent. 



„ carbohydrates 39-0 ,, 

 fat 0-9 X 2-25 = 2-0 



5HJ „ 



Such a calculation, however, simply shows that the digested nutrients 

 in one hundred pounds of the hay contain roughly the same amount of 

 total energy as 51-6 pounds of carbohydrates, viz. about 97-9 therms. 

 It shows nothing whatever regarding the losses of energy which occur 

 during digestion and assimilation nor as to how much remains available 

 to the animal. While in a sense it is a starch equivalent it is not Kellner's 

 starch value. It shows what the hay contains but not what useful eflect 

 it can produce. 



A second misapprehension identifies Kellner's starch value with 

 what has been called the "Physiological heat value," or the "Fuel 

 value," or what the writers have designated as the " Metabolizable 

 energy." 



It is well recognized that not all the energy contained in the digested 

 nutrients is available to the body, but that a considerable proportion 

 of it escapes unused in the metabolic products of the urine and in the 

 combustible gases produced in the digestive tract. In the case of starch 

 some 10 per cent, of its energy escapes in the methane excreted by 

 cattle, while none of it is lost in the urine. One pound of digested starch, 

 therefore, is capable of yielding in the form of heat in the body of a 



' Feeds and Feeding. 15th eJ., p. liOl). 



