WORK PRODUCTION 561 



more particularly of haemoglobin, would be necessary and a 

 liberal supply of protein seems to assist in securing this. If 

 any of these conjectures should prove to be true the proteins 

 may play a not insignificant role in the production of muscular 

 work without any evidence of the fact appearing in the total 

 nitrogen excretion. 



668. The protein requirement. No specific investigations 

 regarding the minimum protein requirement of the work horse 

 seem to have been made, but the extensive experiments of 

 Wolff, Grandeau, Miintz and others referred to on previous 

 pages afford numerous instances in which entirely satisfactory 

 results were obtained from rations comparatively low in pro- 

 tein, although in none of them was the supply reduced to the 

 maintenance requirement. Similarly, in Langworthy's ex- 

 tensive compilation 1 of rations fed in practice, numerous ex- 

 amples of low protein rations are to be found. 



In fact, it would be difficult to compound from ordinary feed- 

 stuffs a ration sufficient to support any considerable amount of 

 work without introducing more protein than is presumably 

 required for simple maintenance. Such being the case, the 

 principal point to be taken into consideration is the effect of a 

 reduced protein supply upon the digestibility of the ration (723- 

 725). Any ration carrying sufficient protein to ensure normal 

 digestion would doubtless furnish ample protein for work 

 production in all ordinary cases, with the possible exception of 

 work at high speed. A nutritive ratio, computed in the usual 

 way (709), of i : 10 or i : 12 would unquestionably ensure ample 

 protein for slow work, and probably for moderately rapid work 

 also. In the case of man, as is well known, experience or tra- 

 dition have led to the general employment of high protein 

 rations by athletes. On the other hand, however, Chittenden 2 

 has shown that the protein supply of athletes and soldiers, as 

 well as that of men of sedentary occupations, may be reduced 

 much below the usual level without loss of efficiency. Even in 

 these experiments, however, the protein supply was much higher 

 than the amounts which recent experiments have shown to suf- 

 fice for the maintenance of nitrogen equilibrium in man at rest 

 or doing only light work. 



1 U. S. Dept. Agri., Office Expt. Sta., Bui. 125 (1903). 



2 Physiological Economy in Nutrition, 1904. 

 2 O 



