妊娠時と授乳時のタンパク質栄養が出生仔の発育におよぼす影響
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概要
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It has been reported that deficiency of protein in mother rats during pregnancy and lactation causes an irreversible retardation of growth and development of the young.In order to confirm the harmful effect of deficiency of protein during pregnancy and lactation, and to compare the harmful effect of the deficiency of protein during the first half of pregnancy with that during the latter half of pregnancy, and to further examine whether the retardation caused by the deficiency of protein during pregnancy can be recovered by normal feeding of mother rats during lactation, a series of experiments was performed by feeding mother rats on protein deficient diets during various periods of pregnancy and lactation.The following results have been obtained.1) When the pregnant rats were fed on a diet containing 5% casein through full terms of pregnancy, the rate of stillbirth was high and a number of young died on the day of birth.The mortality rate of the young was significantly higher than that of the control group and the mean body weight was significantly lower compared with the control group up to the 105th day after birth.2) The harmful effect of protein deficiency during the first half of pregnancy was almost the same as that during the latter half of pregnancy. However, it was noted that the shorter the period of protein deficiency, the lesser the harmful effect on the growth and development of the young.3) The protein deficiency of mother rats during lactation seemed to affect the growth and development of the young to the same extent or more severely than that during pregnancy. The harmful effect of protein deficiency during pregnancy was increased when protein deficient diet was given to mother rats during lactation continuously, but the harmful effect was lessened considerably when mother rats were fed on normal diets during lactation.4) The total number of cells of liver and brain in the young on the day of birth and 21st day after birth was estimated from the DNA contents in the organs of the young. It was found that the number of cells in the organs of the young from the mother rats fed on protein deficient diets was significantly lesser than those from normal mother rats.5) As for the food efficiency and nitrogen balance of the young, no significant difference was found between the young from protein-deficiency mother rats and from normal mother rats.