The effects of zinc intake and exercise on iron status of pregnant Sprague-Dawley rats
The effects of marginal zinc intake and exercise on the iron status of Sprague-Dawley rats during pregnancy were observed. The dams were assigned to one of four groups: zinc marginal (6.18 ppm zinc sulfate), exercise or sedentary; zinc adequate (37.63 ppm), exercise or sedentary. The dams swam everyday for one hour until day 18. Data was collected on days 15, 18, and 21. Anorexia occurred by day 21 in the zinc marginal groups, significantly reducing dam body and organ weights and may be attributed to maternal tissue mobilization in response to increased fetal zinc demands late in gestation. Fetal and placental weights were unaffected. Hemoglobin and hematocrit decreased throughout gestation in the adequate group, and until day 18 in the marginal group, increasing significantly by day 21. Serum iron, TIBC, and maternal liver iron decreased throughout pregnancy although liver and spleen iron stores were higher in the zinc marginal dams. Fetal iron increased significantly independent of treatment. Increased iron status in the zinc marginal dams may be due to enhanced iron uptake when zinc nutriture is low. Overall decreases in serum iron, TIBC, and liver iron reflect the increasing demands of iron from the fetus. Heart weight was significantly higher in the swimmers. The sedentary group weighed more than the exercise group, their hematocrit increased by day 21, and spleen iron stores were significantly higher. No change in hematocrit was found in the exercise dams and their TIBC was greater, revealing an increase demand for iron during exercise. It was concluded that a zinc marginal intake, its resulting anorexia, and the onset of strenuous exercise at conception, affected maternal iron status and weight without harming the fetus.