Plasma prolactin levels in sows during pregnancy, parturition and early lactation

Mean prolactin concentrations in the blood plasma ranged from 4.4 to 13.0 ng/ml during pregnancy up to the 2nd day pre partum. Concentrations increased to 20.3 ng/ml 2 days before and 103.4 ng/ml at 1 day before the start of farrowing. During farrowing values ranged from 124.2 to 147.3 ng/ml. On the 5th day of lactation the prolactin levels had fallen to 43.1 ng/ml.