272 The Feedhuj of Animals 



PHYSIOLOGICAL VALUES 



We are left now to inquire whether we may not 

 use physiological values, in other words the work which 

 a nutrient will perform in the animal body, as a start- 

 ing point from which to calculate relative values. If, 

 for instance, it could be demonstrated that protein has 

 a fixed physiological value twice, and fats three times, 

 that of carbohydrates, it would then be a very simple 

 matter to ascertain what proportion of tlie cost of a 

 ton of cottonseed meal should be applied to each class 

 of nutrients. To illustrate, a ton of average cotton- 

 seed meal contains about 590 pounds of carbohydrates, 

 860 pounds of protein, and 260 pounds of fat. If 

 these ingredients are assumed to have a ratio of value 

 of 1, 2, and 3, then the whole would be equivalent to 

 8,090 units of carbohydrates, the cost of one unit of 

 which would be .8 cent, when we pay $25 per . ton 

 for the cottonseed meal. On this basis it would be 

 necessary to assign to the protein a cost of 1.6 cents 

 per pound, and to the fats 2.4 cents. If our premise 

 were correct we could calculate the cost of the nutrients 

 in any one of the feeding stuffs, and could either 

 ascertain which was the cheapest source of each in- 

 gredient, or by averaging could establish a basis for 

 a general valuation. Unfortunately no such a premise 

 can be correctly formulated. We are not yet wise 

 enough to establish fixed relative physiological values 

 for the three classes of nutrients. 



It may be asked, do we not know the heat value of 

 a unit of each of the nutrients, of protein, of starch, 



