THE ACID-BASE BALANCE IN ANIMAL NUTRITION I. The Effect of Certain Organic and Mineral Acids on the Growth, Well-Being and Reproduction of Swine

The question of the balance between acid and base-forming mineral elements in foodstuffs has figured more or less prominently in discussions of rations for both man and animals during the last decade. Based principally on the work of Forbes,' Sherman and Gettler2 , and !Castle3 , there has developed a considerable tendency to emphasize the necessity for a balance between potential acid and base in the mineral constituents of rations. In this preliminary discussion human dietary standards will figure, as well as rations for animals, but in reporting our conclusions we shall avoid the too common error of applying data obtained with one species to other species. Much of the early literature on this subject is cited by Forbes and by Sherman and Gettler. The former's discussion of the acid-base balance is very largely theoretical, and much of it is based upon notions which have since been found incorrect. The analyses of Sherman and Gettler, which are the first to show accurately the tru relations of the principal mineral elements in foodstuffs, are very valuable indeed, and their interpretation of their metabolism experiments is conservative, but others have often over-emphasized the necessity of a balance such as they suggest. We wish first to point out certain fallacies in the reasoning of those who insist on the necessity of this balance of ash elements. The interpretation of experiments comparing natural foodstuffs with varying acid and base content is difficult, because the character and composition of the ash, aside from its acid or basic properties, may have much influence on the results, as has been shown by McCollum\ and by Osborne and Mendel5 . Other elements in the ration, such as the character of the proteins, may be limiting factors. A prime essential in fundamental nutrition ex· periments is that unknown factors as far as possible should be limited to one. 'l'hen only is complete interpretation and generalization possible. The tendency has often been to accept too readily