Studies on Lactation

Abstract

By using the method described in the preceding paper, lactation studies were carried out on rats using various dietary principles. The food materials tested were either fed in place of the casein of the basal diet or as added daily supplements. The lactation promoting factor was found to be present in liver, egg, round, kidney, alcohol-water extract of liver, diets of higher protein level (egg casein), water extract of autolyzed liver or egg, Witte's peptone, blood fibrin, lactalbumen, cystine and a combination of 1 part cystine, 1 part glycine and 1 part glutamic acid fed with only 12 parts of casein and the other constituents of the basal diet. This last mixture which simulates glutathione gave the best results, although cystine alone as supplement showed a remarkable effect. The factor was not present in the unsaponifiable fat of egg, in lecithin, extra wheat germ oil, extra cod liver oil, extra lard, Armour's peptone, glycine or K₂S. The authors believe that cystine or glutathione acts in some was as a mammary stimulant.