Masters Theses

Date of Award

12-1971

Degree Type

Thesis

Degree Name

Master of Science

Major

Animal Science

Major Professor

Sam L. Hansard

Committee Members

Karl M. Barth, C.C. Chamberlain, M.C. Bell

Abstract

Although manganese has been demonstrated to be required for normal life processes, little information is available on the placental transfer and maternal-fetal utilization of this mineral in the bovine. Nine pregnant and three non-pregnant heifers were used in this study. They were dosed with a tracer level of radio-manganese for blood balance and subsequent placental transfer and maternal-fetal manganese utilization studies. Results of this study suggested total blood radio-manganese levels to drop from 14% of the administered dose at 3 hours to 1.8% after 144 hours. Blood clearance studies indicated that equilibrium between red cells and plasma was reached 38 hours post-dosing, and further data suggested that approximately 50% of the plasma manganese was protein bound. Eighteen percent of an intravenous 54Mn dose was excreted by pregnant heifers 144 hours after dosing. Bile appeared to be a major excretory pathway for manganese, and urine a minor excretory pathway. Liver served as the main metabolic pool for manganese in both the dam and fetus. Data suggested that heifers retained a calculated 1.16 mg manganese per day and deposited 82 ug (7.0% of that retained) in the total products of conception. Third-trimester bovine fetuses (272 days) contained 19.1 mg stable manganese; placenta, 2.10 mg and placental fluids 1.20 mg, for a total of 22.4 mg manganese in the total products of conception. Pregnant heifers deposited in the total products of conception a calculated 82 ug manganese per day, suggesting that 82 ug manganese per day was needed to support the products of conception in the pregnant heifer.

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