1 88 AN AGRICULTURAL WAR PROBLEM 



which the staff of the Cambridge Nutrition Insti- 

 tute have been working for some time. It has 

 already been stated that every animal requires 

 daily a certain amount of protein to make good 

 the wear and tear of its working parts, or tissues 

 as they are called. Twenty years ago physiolo- 

 gists would have been satisfied with this statement. 

 But recent work on the chemistry of the proteins 

 has shown the need for caution in applying definite 

 standards for protein requirements. The protein 

 of wheat for instance has been shown to yield on 

 digestion something like 40 per cent, of one con- 

 stituent called glutaminic acid. This particular 

 constituent is not required in large quantities by 

 animals. If an animal is given all its protein in 

 the form of wheat it will require more than the 

 standard amount of protein, for much of the glu- 

 taminic acid of the wheat protein will be in excess 

 of the animal's requirements for that substance 

 and will go to waste. The animal will be able to 

 repair its tissue waste with a smaller amount of 

 protein if part of it is given in the form of a protein 

 which contains a smaller proportion of glutaminic 

 acid and consequently more of the other protein 

 constituents. Unfortunately our knowledge of the 

 constituents of the proteins of many fodders is far 

 from complete, but there is a much better chance 

 of getting a mixture of constituents proportionate 

 to the needs of the animal if a mixed ration is 

 given than if the animal is fed on one food only. 



