Concentration of bovine placental lactogen in dairy and beef cows across gestation

The concentration of bovine placental lactogen (bPL) was determined in five dairy heifers and five beef cows across gestation. Blood samples were collected beginning at day 45 post insemination and once every two weeks until two d postpartum. Concentrations of bPL in maternal serum ranged from undetectable (< .25 ng/ml) to 2.93 ng/ml and there were no significant differences between dairy and beef animals. Peak concentrations were observed at day 215 of gestation and remained high until just prior to parturition. These results suggest that bPL concentrations follow a pattern similar to that in other species that produce placental lactogen.