70 



Table 9. — Calculated "true nutritive value'' of 1 pound of different feeding stuffs. 



Feeding stufis. 



Meadow hay (average qual- 

 ity) 



Alfalfa hay cut at begin- 

 ning of bloom , 



Red clover hay 



Winter wheat straw 



Oats (medium quality) 



Maize 



Field beans 



Peas 



Air-dry disembittered lu- 

 pines 



Linseed cake 



Potatoes 



Carrots 



Drv mat- 

 ter. 



Per cent. 



85 



84 

 84 

 86 



87 

 87 

 86 

 86 



86 

 88 

 25 

 15 



Crude 

 fiber. 



Pound. 



0.260 



.266 

 .302 

 .420 

 .103 

 .017 

 .069 

 .059 



.157 

 .094 

 .010 

 .016 



Total di- 

 gestible 

 nutri- 

 ents.a 



Pound. 



0.391 



.453 

 .407 

 .181 

 .615 

 .785 

 .720 

 .687 



.645 

 .690 

 .226 

 .113 



Labor expended in 

 chewing and di- 

 gestion. 



True nutritive 

 value. 



In 

 terms of 

 energy. 



Calories. 



376 



394 

 429 

 535 

 224 

 148 

 200 

 183 



294 



225 



49 



37 



In terms 

 of nutri- 

 ents.'.* 



Pound. 



0.182 



.234 

 .168 

 -.116 

 .491 

 .703 

 .609 

 .586 



.482 

 .565 

 .199 

 .092 



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



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

 table. The authors call attention to the investigations which showed 

 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 combus- 

 tion. Provided the labor of digesting a mixed ration does not exceed 

 2,100 grams (4.63 pounds, or 8,316 calories), the digestible nutrients in 

 straw have a positive value. Provided the labor of digestion is greater 

 than this an excess of straw would onh' increase the internal muscular 

 work, so that approximateh' 116 grams (0.256 pound) of nutrients per 

 kilogram is of no value for the body. 



From the table the amount of any food or combination of foods 

 required for maintenance ma}" be calculated, according to the authors, 

 as follows: When a horse weighing 500 kilograms (1,100 pounds) is fed 

 hay alone, 8.2 kilograms (18.01 pounds) would be necessary, since, as 

 previously stated, 3,200 grams (7.05 pound.s) of nutrients are required 

 for maintenance. As shown b}" the table, a kilogram of hay contains 

 391 grams (0.86 pound) total nutrients. 



If the ration consists of 3 kilograms {6.Q pounds) of hay and 1 kilo- 

 gram (2.2 pounds) of straw and it is desired to make up the balance 

 with potatoes, the amount necessary may be calculated as follows: 



Since the horse requires for maintenance 3,200 grams (7.053 pounds) 

 nutrients, there remain 1,846 grams (1.07 pounds) total nutrients to be 

 supplied by potatoes. This, divided b}^ 226, the total nutrients in a 

 kilogram (2.2 pounds) of potatoes, gives 8.2 kilograms (18.04 pounds) 

 as the amount which must be added to the ration. 



