1995 Volume 41 Issue 1 Pages 63-70
Peripheral plasma progesterone concentrations were monitored throughout gestation in Holstein cows after non-surgical transfer of in-vitro fertilized embryos. Cows (n=12) were divided into 2 groups; Group 1=single embryo, Group 2=twin embryos. To induce multiple corpora lutea prior to the embryo transfer, 3 cows in each group (n=6) were randomly treated (treated cows) with either porcine follicle stimulating hormone (FSH) or pregnant mare serum gonadotropin (PMSG) followed by prostaglandin F2α (PGF2α), commencing in the mid-luteal phase of the cycle preceding pregnancy. In the remaining cows (n=6) estrus was synchronized by using PGF2α (untreated cows). Treated cows had a significantly higher plasma progesterone concentration throughout gestation than untreated cows (P<0.001). Treated singleton cows had higher plasma progesterone concentration in the first trimester than in the later trimesters (P>0.05). Treated twin-bearing cows had a significantly higher plasma progesterone concentration in the first and the third trimester compared to the second trimester (P<0.001). There was no significant (P>0.05) difference in plasma progesterone concentration throughout gestation between untreated singleton and twin-bearing cows. A distinct undulation in the plasma progesterone profile was seen in all the groups between days 20 to 25. To conclude, the plasma progesterone secretory profile was indistinguishable between untreated singleton and twin-bearing cows, and multiple corpora lutea induced by gonadotropin administration significantly boosted the progesterone pool throughout gestation.
