Circulating plasma protein concentrations in the fetal and neonatal sheep

Fetal and neonatal ovine plasma protein and lactate dehydrogenase concentrations have been measured between 124 and 146 days gestation in the chronically catheterized fetal sheep and in the newborn lamb. Fetal plasma protein concentration ranged from 24.7 to 77.0 mg·ml–^–1 and increased at a rate of 1.65 mg·ml–^–1·day–^–1. In contrast, in the first 10 days of neonatal life plasma protein concentration fell steadily at a rate of 2.64 mg·ml–^–1·day–^–1. Fetal plasma lactate dehydrogenase concentration increased at a rate of 0.014 IU·ml^-1·day–^–1 during the period of study. The increase correlated significantly with the rise in fetal plasma protein concentration. In contrast, in the newborn lamb no significant change in plasma lactate dehydrogenase concentration was observed during the first 10 days after birth.