Effect of dietary protein level and thyroxine on vitamin A depletion from liver in chicks

Abstract

1. The effect of dietary protein level and supplementation with thyroxine and thiouracil on depletion of liver stores of vitamin A, on the percentage of liver vitamin A in the alcohol form and on the plasma level of vitamin A and protein has been studied in chicks. In an experiment with cockerels the relation was investigated between the vitamin A level of plasma and the electrophoretic pattern of its proteins.2. Liver vitamin A depletion was considerably reduced by lowering the dietary protein level.3. Protein malnutrition lowered the percentage of vitamin A found in the liver in the alcohol form.4. Depletion of vitamin A from the liver was related to the percentage of vitamin A in the alcohol form.5. Thyroxine increased both vitamin A depletion from the liver and the percentage of vitamin A in the alcohol form, whereas thiouracil had the opposite effect.6. Plasma vitamin A, and plasma protein contents were significantly lowered in cockerels receiving a 5% protein diet. The drop in plasma protein level was essentially caused by a reduction of the albumin fraction. No significant change in the levels of globulins was observed even after a 4-week period of protein malnutrition.7. When the dietary protein level was restored to normal both the albumin and vitamin A levels in plasma increased.