Abstract
The effects of dietary protein levels (high protein diet, HPD, 60; standard protein diet, SPD, 30%; low protein diet, LPD, 7.5%) on the development of various symptoms due to vitamin A deflciency were demonstrated in chicks. The result obtained showed that, at an early stage of vitamin A deficiency, the urinary excretion of uric acid in chicks fed a SPD without vitamin A was markedly increased compared with that of pair-fed control. When newly-hatched chicks were fed diets without vitamin A ad libitum, urate accumulated in the kidneys, and growth stopped earlier in chicks fed the HPD diet than those in the SPD group. An increase of liver xanthine dehydrogenase [EC 1.2.1.37] activity with a vitamin A deficiency was observed in both the HPD and SPD groups, but not in the LPD group. The ratio of increase in the HPD group was higher than in the SPD group. The decrease of vitamin A concentrations in the liver of chicks fed the HPD was much more rapid than in the SPD group under the condition of vitamin A deficiency. In contrast, these symptoms were not observed in the vitamin A deficient LPD group, and the decrease of vitamin A in the liver was quite slow. The total DNA, RNA, and protein concentrations in the liver were not affected by vitamin A deficiency at every protein level for all experimental stages. However, a transitory increase of the total lipid content was observed in the SPD group compared with that of control group on the twenty first day.
