Walter C. Russell

Effect of excess essential amino acids on growth of the white rat

Abstract Of the ten essential amino acids tested, only lysine and methionine caused definite growth repression when fed in excess. It is concluded that the repression is a property of these two compounds and is not due to amino acid imbalance.

Relation of vitamin B12 to liver basophilia.

Summary The growth of weanling white rats was stimulated by inclusion of vitamin B12 or of whole dried liver in the diet. Rats which received no B12 or liver grew poorly and showed little or no liver basophilia, whereas those which received B12 or liver grew well and showed considerable cytoplasmic basophilia in their liver cells.

Relation Between Vitamin A Potency and Carotene Content of Green Plant Tissue.

The finding that carotene is provitamin A for certain species-raises the question as to whether a direct determination of the carotene content of plant tissue, coupled with information with regard: to the vitamin A potency of isolated carotene, could be substituted for the extended biological assay. Euler, Demole, Karrer and Walker 1 report that a carotene determination in plant material discloses the magnitude of its vitamin A activity. For the determination of carotene a colorimetric method was used, based on the original procedure of Willstatter and Stoll 2 but modified after critical study by one of us. 3 The vitamin A technique was essentially that employed by Sherman and has been referred to in an earlier publication. 4 Alfalfa samples 45, 46 and 49 were taken from adjacent parts of the same field. Nos. 45 and 46 were dried in a mechanical drier by artificial heat within a few hours after cutting and No. 49 was sun-dried in the field. Samples 61 and 62 were artificially-dried and sun-dried, respectively, but from different parts of the country. A stock solution of carotene from carrots was prepared by dissolving a weighed amount of the crystalline substance (M.P. 169-171°, corr.) in ethyl laurate and olive oil. A dilution was made with olive oil every 2 weeks and in order to insure a constant level of carotene intake a colorimetric determination was made before each dilution. Hydroquinone was added to all solutions to the extent of 1 mg. per cc. as an antioxidant. Table 1 displays the feeding levels which are in a comparable range as to rat growth response.

Plant Pigments in the Nutrition of the Chicken.

Karrer, Euler and Rydbom 1 have demonstrated that carotene has provitamin A properties for the chicken but that xanthophyll is without effect in this regard. Evidence has been presented by Capper 2 that carotene is converted to vitamin A by the chicken. The present experiment was an attempt to confirm the results of Karrer and his associates and to extend the study to include chlorophyll. In addition a study was made of the uric acid 3 content of the blood, it having been observed in earlier studies that this constituent increases in amount in the vitamin A deficient condition. Newly-hatched White Wyandotte chicks were placed upon a vitamin A deficient ration: 52.5% white corn, 20% wheat middlings, 10% dried skim milk, 10% meat scrap, 5% wheat bran, 0.5% sodium chloride, 1% calcite flour and 1% steamed bone meal. Sufficient irradiated ergosterol was used to protect against leg weakness. On this ration retardation of growth begins between 3 and 4 weeks of age. The pigments were dissolved in ethyl laurate and dilutions made with cottonseed oil. The daily allowance of each pigment was 0.03 mg. by capsule. Supplementation with carotene (M.P. 170°-173°) began at 26 days, with xanthophyll (M.P. 173°), at 27 and with chlorophyll at 31 days. An immediate growth response took place when carotene was fed but the birds which received the xanthophyll and the chlorophyll not only failed to grow, but lost weight and died within 2 weeks. Their behavior was essentially that of the non-supplemented control group. Nine or more individuals were used in each group.