Placental transfer of phosphorus in sows maintained on high and low levels of dietary manganese

¹ Department of Animal Husbandry and Nutrition, University of Florida, Gainesville, Florida

Placental transfer of phosphorus was studied in 16 young sows which had been maintained on high and low levels of dietary manganese during their first gestation. Radiophosphorus absorption and the concentration of total phosphorus were found to be directly related to the weight of the fetus. Also, the absorption of P³² and the concentration of phosphorus was essentially the same in fetuses from sows on different levels of dietary manganese. Fetal femurs metabolized P³² more rapidly than did maternal femurs, fetal hearts and fetal livers, while maternal livers showed more activity than any other maternal or fetal organ. Small fetuses at the 60th and 80th day of gestation had a higher specific activity than larger fetuses of the same age. Radiophosphorus placental transfer rate increased steadily during the last half of pregnancy.