41 



ents, and 1 pound of oats 0.015 pound of nutrients. As regards 

 nutritive value, hay and oats are therefore commonly' said to be to 

 each other as -100 : 600. As shown b}- the experiments referred to, 

 0.123 pound, or 20 per cent of the total nutritive material present 

 in 1 pound of oats is expended in the labor of chewing and digesting 

 them. In the case of 1 pound of hay, 0.102 pound, or 4:9 per cent of 

 the total nutritive material, is required for the same purpose. There- 

 fore hay and oats stand reall}^ in the proportion of 200 : 490. In other 

 words, oats surpass hay in feeding value two and one-half times instead 

 of one-half time, as they are ordinarily assumed to do. 



"TRUE NUTRITIVE VAI-UE" OF FEEDING STUFFS. 



. Taking into account the internal muscular work required to chew 

 and digest foods and deducting this from the digestible nutrients pres- 

 ent in the foods, what we ma}' call the "true nutritive value" of a 

 number of feeding stuffs was calculated by Zuntz with special refer- 

 ence to horses. The results are shown in the following table: 



Table 4. — Calculated " fitie nutritive value" of 1 jiound of different feeding stuffs. 



a Protein, plus carbohydrates, plus crude fiber, plus fat multiplied by 2.4. 



As will be seen, the true nutritive value of straw is negative in the 

 above table. In this connection it was stated that so long as heat 

 alone is considered, the digestible nutrients in straw should be given 

 their full value as shown by the heat of combustion. Providing the 

 labor of digesting a mixed ration does not exceed 4.63 pounds, or 

 8,316 calories, the digestible nutrients in straw have a positive value. 

 If the labor of digestion is greater than this, an excess of straw 

 would only increase the internal muscular work, so that approximately 

 a quarter of a pound of nutrients per pound is of no value for the 

 bod3^ 



25352— No. 170—03 4 



