I am glad you have brought up the point that tlie figures of the 

 chemist ouly tell how much muscle-making and fat-making food the 

 material contains. He cannot find out in the laboratory whether or 

 not the animal can use it all after it is taken into the stomach. We 

 must make feeding experiments with the animals themselves. This 

 point has been carefully studied for many years and we now know 

 approximately how much of the two foods in our common feeding- 

 stuffs the animal can use. You will notice that over the columns of 

 fat-making and muscle-making foods in the table is " Pounds of 

 digestible nutrients." This means that the figures given are not the 

 whole amount of food in the feeding-stuff, but only that part which 

 the animal probably can use. In making up your rations, therefore, 

 these figures may be taken as they stand without deducting anything 

 for waste. 



On page 140 of the bulletin you will find a table of '• Feeding 

 Standards ;" or the average amount of food which many experi- 

 menters have found to be best suited for making milk, beef or for 

 other purposes. I will copy three items in it to show you how the 

 table works : 



Oxen at rest in stall 



Oxen heavily worked 



Milk cows, Wolff's standard. 



Nutritive 

 ratio. 



1:11.9 

 1 :63 

 1 : 5.4 



Here is a good illustration of the fact that anmials lohich are 

 hard at loork need a liberal supply of iixuscle-makers. The taljle 

 shows that oxen in the stall need only IT pounds of feed a day 

 (that is, after the water has been dried out of it), while those in the 

 yoke need 26 pounds. But the difference is not only in bulk ; it is 

 also in composition. Oxen at rest can get along with only seven- 

 tenths of a pound of muscle-making food a day, while oxen at work 



555 



