Feeding Standards — Calculating Rations. 



107 



129. Coefficients of digestibility.— The digestible portion of each 

 nutrient in a feeding stuflt", expressed in per cent, is termed its 

 coefficient of digestibility. The nutrients of feeds are not wholly 

 digestible, a part always passing thru the animal without having 

 been dissolved by the digestive fluids and thereby being made 

 usable. Digestion trials showing what per cent of each nutrient in 

 feeds is digestible have been collected in Table II of the Appendix, 

 from which the following data are taken : 



Example Table II, showing the digestion coefficients of the feeding stuffs 

 given in Table I. 



The first line of the table shows that, taking the average of 31 

 digestion trials with corn stover, 36 per ct. of the crude protein, 64 

 per ct. of the fiber, 59 per ct. of the nitrogen-free extract, and 67 

 per ct. of the fat are digestible. The concentrates — corn, oats, etc. — 

 are usually much more digestible than the roughages — corn stover, 

 oat straw, etc. 



130. Digestible nutrients. — The digestible nutrients in a feeding 

 stuff are found by multiplying the pounds of each nutrient it con- 

 tains by the numerical coefficient of digestibility for that nutrient 

 in the given feed. Example Table III on the next page is a fragment 

 of the extensive Table III of the Appendix. Its data are derived 

 by multiplying the nutrients in each feed as given in Table I by 

 their corresponding coefficients of digestibility given in Table II. 

 After determining the several digestible nutrients it is customary 

 to combine the fiber and nitrogen-free extract under the group-term 

 carbohydrates. 



Table I shows that average corn stover contains 3.8 lbs. of crude 

 protein, 36 per ct. of which is digestible according to Table II. 



