288 



ELEMENTS OF AGRICULTURE 



It will be seen that 79 per cent of the protein of wheat 

 bran is digested, while 21 per cent passes through the 

 animal unused. But only 11 per cent of the protein in 

 wheat straw is digested. In general, the grain feeds are 

 much more digestible than roughage hay, straw, etc. 



264. Digestible Nutrients in Feeds. By combining the 

 above table with the table of compositions, we can get 

 the amount of digestible material in each food: 



Corn contains 10.3 per cent of protein, of which 76 

 per cent is digestible; or it contains 7.8 per cent of diges- 

 tible protein. Similarly, it contains 1.2 per cent of diges- 

 tible crude fiber and 65.5 per cent of nitrogen-free extract. 

 These are added to give the amount of digestible carbo- 

 hydrates, or 66.7 per cent. This is the manner in which 

 Appendix table 8 is calculated. 



265. Effect of Time of Harvesting on Digestibility. 

 When hay ripens, much of the food material is trans- 

 ferred to the seeds. These seeds are so small and hard 

 that they are not digested by the animal, hence, hay that 

 is cut when ripe is not very digestible. (Fig. 90.) In 

 the case of corn, the seed is digestible, hence the total 

 product averages higher in digestibility as the plant ripens. 

 The total product is also much more per acre. Therefore, 

 we cut hay plants when green and grain crops when ripe. 



