DEPOSITION OF COPPER, MANGANESE, ZINC, AND SELENIUM IN BOVINE FETAL TISSUE AT DIFFERENT STAGES OF GESTATION

Developmental changes of Cu, Mn, Zn, and Se in fetal liver and kidney and the intracellular distributions were determined. Fetuses were obta ined from crossbred beef heifers (n = 25) that were slaughtered at dif ferent stages of pregnancy. Fetal age was estimated from crown to rump measurements. Selenium concentration of fetal liver increased from d 145 to 195 but decreased from d 195 to 245. Fetal age did not affect C u, Mn, or Zn in fetal liver and kidney or Se in kidney. Bone Ca signif icantly decreased with fetal age,;but neither bone P nor Ca:P ratio ch anged. Liver Zn concentrations were correlated negatively with kidney Mn but positively with liver Se. Within fetal liver, the crude nuclear fraction had the largest amount of Cu, and the largest amounts of Zn and Mn were in the cytosolic fractions. The ribosomal fractions contai ned the least Cu, Zn, and Mn. Results indicate the normal changes that occur in tissue concentrations of minerals in the developing bovine f etus. Storage of minerals in fetal tissue reflects fetal demands for g rowth and the ability of the dam to transfer minerals.