METABOLISM AND FOOD 85 



and straws carried out in a similar manner showed 

 that from 1 kilo dry substance the following addi- 

 tions of fat, in grams, were to be expected, if the 

 digested materials had also behaved as do the 

 pure nutrients — 



Wheat straw. Oat Barley Meadow hay. Clover Grass After- 

 a b straw, straw, a b hay. hay. math. 



Fat calculated 104 82 109 117 129 156 125 153 124 

 „ actually- 

 found . 21 24 66 79 81 109 85 85 79 



Difference 83 58 43 36 48 47 40 48 45 

 Percentage dif- 

 ference be- 

 tween calcu- 

 lated and 

 observed in- 

 crease of fat 80 71 40 31 37 30 32 36 36 



Here very different results are obtained to those 

 with the oil cakes. The calculated increase of fat 

 does not agree with that observed in the animal. 

 In each case the fodder has yielded less fat than 

 was expected, supposing the digested nutrients in 

 the hay and straw to act as do the pure, isolated 

 nutrients. The difference in the wheat straw is 

 70-80%, in the oat and barley straws 30-40%, and 

 with the various varieties of hay also 30-40%. 

 If, then, in calculating rations the same value were 

 given to the digestible materials of the coarse 

 fodders as to those of the oil-cake meals, the food 

 value of hay and straw would be estimated 30-80% 

 too high. The quantity of digestible nutrients 

 without reference to their effect cannot therefore 



