The food of infants comes in the main from two sources, human milk and cows' milk, the former being the natural food and the latter the best substitute we have when the former supply fails us. A brief description of these two milks is necessary for a clear conception of the subject.
The percentage of fat in cows' milk varies with the individual cow and the species. The milk of the ordinary grade cow, the Holstein or Ayrshire, contains 4 per cent, or less of fat, and that of the Jersey or Guernsey 4 per cent., or more, of fat. The fat is held in a coarser emulsion and separates more easily than that of human milk. There are other differences in the chemical and physical composition of the two milk-fats, but these will not be taken up in this paper.
Human milk normally contains, in round numbers, about 4
TALBOT FB. PHYSIOLOGY AND PATHOLOGY OF THE DIGESTION OF FAT IN INFANCYTHEIR APPLICATION TO INFANT-FEEDING. Am J Dis Child. 1911;I(3):173–192. doi:10.1001/archpedi.1911.04100030003001