38 



FEEDS AND FEEDING 



dry matter. Similarly, it was found that of the 631.2 grams of crude 

 protein in the feed, 270.0 appeared in the feces, and 361.2 grams, or 

 57.2 per ct., was digested. In a like manner the percentages of the 

 other nutrients that were digested were determined. 



Digestion trial with a steer fed clover; average for 1 day 



67. Digestibility determined by difference.- Some feeds cannot be fed 

 alone, as was done in this trial. For instance, horses and ruminants are 

 not fed only concentrates without hay or other roughage. Again, while 

 pigs may be fed on grain alone, such feeds as tankage and linseed meal 

 are too rich in protein to be fed thus. The digestibility of these feeds 

 must therefore be found by difference, instead of directly. 



This method of determining the digestibility of a feed is illustrated 

 in the following: To find the digestibility of ground corn, after 

 Armsby had carried on the digestion trial with red clover hay which has 

 been previously described, he then fed the same steer a ration of 3,700 

 grams clover hay and 4,000 grams ground corn during another digestion 

 trial. The hay in this ration contained 3,186.4 grams dry matter and 

 the corn, 3,450.8 grams dry matter, making a total of 6,637.2 grams. 

 Of this amount there was voided in the feces 1,577.4 grams, leaving 

 5,059.8 grams as the total digested from both hay and corn. In the 

 previous trial it was found as the average of 2 periods that 59.4 per 

 ct. of the dry matter in the clover hay was digestible. Taking 59.4 per 

 ct. of 3,186.4 grams, the total amount of dry matter in the clover hay 

 fed, gives 1,892.7 grams, which was the probable amount of dry matter 

 that was digested from the hay. Subtracting 1,892.7 grams from 5,059.8 

 grams, there was left 3,167.1 grams, which was taken as the amount of 

 dry matter digested from the 3,450.8 grams of total dry matter in the 

 corn which was fed. This therefore gave 91.8 per ct. as the percentage 

 of the dry matter which was digested. In a similar manner there were 

 determined the percentages which were digested of the different nutrients 

 in the corn. 



68. Coefficients of digestibility. The percentage of each nutrient 

 digested in a feeding stuff is termed the coefficient of digestibility, or 

 digestion coefficient, for that nutrient in the feed. 



As is explained later in this chapter, due to the fact that cattle and 

 sheep are ruminants, they digest feeds high in fiber more completely 



