Peripartum acute-phase protein serum amyloid-A concentration in plasma of cows and fetuses

Concentration of the acute-phase protein serum amyloid-A (SAA) was measured by means of an indirect ELISA method, in plasma of 3 pregnant cows and in plasma taken by cannula from another 4 pregnant cows and, by separate cannula, from their fetuses. Blood samples were taken daily from approximately 72 hours before until 72 hours after parturition. After parturition, SAA concentration increased significantly (P < 0.05) in maternal plasma. In fetal plasma, only a nonsignificant increase was found at time of delivery. The concentration of maternal SAA started to increase within the first 24 hours after delivery, reaching a peak value between 24 and 48 hours after delivery. In the aforementioned plasma samples from the 4 pregnant cows and their fetuses, the concentration of maternally derived cortisol increased nonsignificantly after parturition. The concentration of fetally derived cortisol was significantly (P < 0.05) increased at parturition (t = 0), compared with the initial fetal cortisol concentration at 120 hours before delivery. Peripartum concentration of maternal SAA increased and maternal cortisol remained low, whereas fetal SAA concentration remained low and fetal cortisol concentration increased. These findings indicate possible suppressive action of fetal cortisol on fetal SAA production. However, it might be argued that the main cause of the difference in SAA concentration is the difference in tissue damage between cows and fetuses at parturition.