Simplified Rations for Guinea Pigs Suitable for Assay of the Grass Juice Factor. ∗

Previous publications from this laboratory have described studies on the grass juice factor in which both rats 1 2 and guinea pigs 3 have been used for assay purposes. The basal ration used for each of the species was mineralized winter milk. Since certain laboratories have difficulty in obtaining milk from cows fed rations known to be deficient in the grass juice factor, we were interested in developing a purified ration which could be used in place of the milk. This paper gives a preliminary account of the results obtained when dry rations designed to be low in the grass juice factor were used for guinea pigs.

The following rations were used:

The diet and water were supplied ad libitum. Each guinea pig was given 2 cc of orange juice daily to supply the vitamin C requirement. The above diets invariably maintain rats in good condition although these animals may show lower than normal rates of growth depending upon previous history. However, when guinea pigs weighing 300–450 g were placed on any one of these rations, death occurred in 3 to 10 weeks. Among the symptoms observed prior to death were severe loss in body weight, muscular atony and weakness, thinning of the hair coat, and stiffening of the joints. In some cases head retraction was noted immediately preceding death. Autopsy showed no signs of rickets or scurvy. In some cases darkened areas on the lungs were observed, suggesting that the animals in their enfeebled condition had contracted pulmonary pneumonia which probably was the terminal cause of death. In many of the animals, however, the stomach linings were found to contain numerous petechial hemorrhages, accompanied in most cases by hemorrhagic ulcers.