516 EXPERIMENT STATION RECORD. 



varies with the animal to which it is fed, the aid of the respiration 

 apparatus or calorimeter is indispensable. 



We need also experiments Upon the food requirements for produc- 

 tion of various sorts. T can jiause only to indicate a few of the 

 pi'oblenis uudci' this head. 



First, we liave the proteid requirement. The question of the inini- 

 nnuu proteid re(|iiirement has been brought to the fore by the investi- 

 gations of Chittenden and others ujDon human nutrition. Since 

 protein is usually the most expensive ingi'edient of rations, we need 

 determinations of the actual amounts required, for instance, for 

 growth at different ages. It would be interesting to determine 

 whether there are individual differences in the rate of growth of 

 proteid tissue, and whether this rate of growth can l)e stimidated by 

 an excess of jDroteids in the ration. Similarly, for milk production, 

 we attribute a stimulating effect to the proteid supply in excess of 

 that appearing in the milk and excreta, but have we any real demon- 

 stration of such a fact? In the case of our working animals, we 

 know that the work is done largely at the immediate expense of the 

 nonnitrogenous nutrients, but have the proteids no function* in the 

 matter, and is the universal practice of athletes, for example, to con- 

 sume large amounts of proteid food a mere habit or tradition and of 

 no significance to us in the feeding of work animals? Questions 

 such as those last indicated can, of course, be studied purely from the 

 standpoint of the nitrogen balance of the body, but the history of 

 investigations upon work production makes it evident that a com- 

 l^rehensive study of the subject requires also a study of the total 

 metabolism, and this again necessitates the use of the res])iration 

 ajDparatus or calorimeter. 



Variations in the total food demand due to individuality, age, 

 weight, condition, and the like appeal for solution, and that solution 

 can be reached only by accurate scientific methods. Similarly, in 

 milk production the question of the factors influencing the distribu- 

 tion of the food between milk and tissue production needs thorough 

 investigation. Again, the influence of such factors as temj^erature, 

 water consumi^tion, exposure to storms, humidity of the air, and the 

 like needs be only mentioned to show the need for further systematic 

 investigation. 



Finally, a mere mention of the influence of feed upon the quality 

 of the product must serve to simply hint at a most fertile field of 

 investigation. 



But because I have thus far dwelt almost exclusively upon the 

 scientific and almost recondite aspects of the study of feeding, I 

 would not be thought to hold that this is the only kind of work that 

 ought to be undertaken or that no one should venture upon the field 

 with any less formidable equipment than a digestion stall and an 



