MILK IN ITS RELATION TO INFANT FEEDING 



Isaac A. Abt, M. D., and A. Levinson, M. D., Chicago 



Introduction. — Although milk has been universally recognized 

 as the food for infants since the beginning of the human race, a 

 knowledge of the scientific relation of milk to infant feeding is of 

 comparatively recent origin. Not only did the ancients know 

 httle about the composition of milk, but until recently even mod- 

 ern chemists have had only a meager knowledge of the chemistry 

 of milk, either human or bovine. Though there is still much to 

 be learned, great progress is being made in the study of nulk as it 

 affects infant feeding through the valuable researches of biochem- 

 ists and bacteriologists and through the tireless efforts of pedia^ 

 tricians all over the world. 



Milk is the food of most, animal species, nature having pro- 

 vided each mother with milk for her infant. Particularly did 

 nature intend that the human infant should be suppHed with 

 human milk — the milk of its mother. Yet it frequently happens 

 that the infant is deprived of mother's milk either entirely or in 

 great measure. It then becomes necessary to have recourse to 

 the milk of other animals. Thus it is that infants have been fed 

 on the milk of cows, sheep, goats, asses, camels, etc. The nulk 

 most commonly employed, however, as a substitute for mother's 

 milk is the milk of the cow. 



Mother's Milk and Cow's Milk. — A Study of Their Compara- 

 tive Values. — Human and cow's milk differ materially both quanti- 

 tatively and qualitatively. The quantitative differences are il- 

 lustrated in the following table: 



Mother's milk, Cow's milk, 



per cent. per cent. 



Fat 4.0 3.5 



Protein 1.5 4.5 



Sugar 7.0 4.5 



Salts 0.2 0.5 



■Water 87.30 87.25 



Qualitatively the two kinds of milk differ in the character of 

 their salt and protein content. The salts of mother's milk con- 

 sist principally of alkaline bases, while those of cow's milk are 

 chiefly of the alkahne earths, such as calaium and magnesium. 

 The protein of mother's milk contains a larger quantity of lactal- 

 bumin and a smaller amount of casein than does that of cow's 

 milk. Many make the greater predominance of casein in cow's 

 milk responsible for the large, heavy curds given off by cow's 

 milk when it is acted on by the rennin of the stomach. It is 



584 



