The Relation of the ‘Grass Juice Factor’ to Guinea Pig Nutrition

Abstract

Winter milk supplemented with iron, copper, and manganese is an inadequate diet for young guinea pigs. In contrast to rats, which grow slowly on mineralized winter milk, guinea pigs die on such a diet. Orange juice, brewers' yeast, and liver extract produce little or no beneficial effect when fed as supplements to this diet. Various grasses contain a factor (or factors) which is essential for maintenance and growth of guinea pigs. Small supplements of such grasses enable guinea pigs on a mineralized winter milk diet to grow normally. The active principle of grasses is soluble in the plant juices since centrifuged grass press juice is active. The activity of grasses disappears upon storage at room temperature. It is fairly stable at lower temperatures. It is destroyed to a large extent by autoclaving. From experience with the guinea pig it is probable that this species can be used to good advantage in further studies on the ‘grass juice factor.’