206 ELEMENTS OF AGRICULTURE 



digestible nutrients in any given weight of food. For 

 "instance, from the composition of timothy hay shown 

 in Table V in the Appendix we learn that every 100 

 pounds of such hay contains 5.9 pounds of protein, 2.5 

 pounds of fat, 45 pounds of nitrogen-free extract, and 

 29 pounds of fiber. Digestion experiments show that 

 48 per cent of the protein, 57 per cent of the fat, 63 

 per cent of the nitrogen-free extract, and 52 per cent 

 of the fiber are digestible. Then every hundred pounds 

 of timothy hay must, according to these figures, contain 

 the following amounts of digestible nutrients: 2.8 

 pounds of protein, 1.4 pounds of fat, 28.4 pounds of 

 nitrogen-free extract and 15 pounds of fiber. 



A great many digestion experiments have been made 

 with many different kinds of animals and foods. Such 

 tests are necessary, for different animals have different 

 powers of digestion. A cow, for instance, may digest 

 more of a certain kind of food than a horse, a growing 

 calf may digest more of a food than an old steer. Dif- 

 ferent samples of the same food differ in the amounts 

 of digestible nutrients they contain. It is only by 

 making many tests, and taking their average that 

 reliable figures can be obtained. The experiment 

 stations of this and of other countries have made, and 

 are making, many tests to determine the digestibility 

 of all kinds of animal foods, and in Table VI of the 

 Appendix will be found the averages of the most 

 reliable of these tests for the foods shown in Table V. 

 The figures giving the percentages of the nutrients 

 digested are called digestion coefficients. With 

 the figures in Tables V and VI one may easily calculate 



