Author
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Richards, Mark |
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Submitted to: Biological Trace Element Research
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 10/30/1998 Publication Date: N/A Citation: N/A Interpretive Summary: Trace elements such as zinc, copper, and iron are essential nutrients that are required to support proper fetal growth and development during pregancy. A deficiency of these minerals can lead to adverse consequences that threaten fetal survival, maternal health and viability of the newborn. Therefore, it is important to understand how trace elements are metabolized dduring critical time periods of pregnancy. The purpose of this study was to investigate some aspects of the metabolism of zinc, copper and iron during pregnancy in the pig. Tissue and fluid samples from the mother and each fetus were analyzed at discrete time intervals throughout pregnancy in order to identify specific periods of need. The results of the study provide new insight into trace element requirements for the support of normal fetal growth and development in the pig. Such information is useful to producers and animal scientists interested in improving the efficiency of pig production. Technical Abstract: Zinc, copper and iron levels in maternal and fetal pig tissues and fluids were measured starting on day 30 of gestation and continuing to term (day 114) at 10 day intervals. Fetal hematocrit increased from a low of 19% on day 30 to 32% by day 50, after which, it remained above 30% to term. Aminotic fluid zinc, copper and iron all reached maximal levels by day 60 of gestation. Maternal serum zinc levels fluctuated little during gestation, but fetal serum zinc concentration was significantly elevated above maternal levels during the second trimester. Fetal serum copper levels were significantly lower than maternal values throughout gestation and this was also the case for ceruloplasmin oxidase activity. Maternal serum iron reached its lowest level by day 80 of gestation when rate of transfer of iron to the developing fetuses was high. Fetal serum iron declined throughout gestation, reaching its lowest level on day 100. In general, fetal liver concentrations of zinc, copper and iron were higher than the corresponding maternal values throughout gestation. Distinct increases were noted for fetal hepatic zinc and copper concentrations during the second trimester of pregnancy and these were accompanied by increases in cytosolic and metallothionein-bound zinc and copper levels. Maternal hepatic iron declined during the second trimester reaching its lowest point on day 80, indicative of the shunting of maternal iron reserves to fetal tissues. Fetal kidney metal levels did not demonstrate any distinctive developmental patterns with respect to zinc, copper or iron concentrations, but a general accumulation of each metal was observed as gestation progressed. These results highlight some of the distinct changes in the metabolism of zinc, copper and iron during gestation in the pig. |
