The concentration of vitamin A and its provitamin - beta carotene in bovine retained and not retained placenta

The relationship between oxidative stress that may accompany the periparturient period and retention of fetal membranes (RFM) in cows still rises questions not only about the biochemical mechanisms but on prevention, as well. The aim of the present study was to describe the relationship between placental vitamin A concentrations and its provitamin and placental release with respect to different time and mode of delivery. Pregnant (n=62), healthy cows were divided into six groups as follows: A - caesarian section before term without RFM (n=10), B - caesarian section at term with RFM (n=10), C - caesarian section before term at RFM (n=12), D - caesarian section at term with RFM (n=12), E - spontaneous delivery at term without RFM (n=10), F - spontaneous delivery at term with RFM (n=8). The concentrations of beta carotene and vitamin A in homogenates of maternal and fetal parts of the placenta were determined spectrophotometrically at 325 nm and 453 nm and expressed in _g/g protein (mean±SEM). Values of beta carotene were significantly (p<0.05) lower in the maternal part of the placenta. The opposite relationship was shown by vitamin A concentrations. The comparison of mode of delivery at term in healthy cows showed, opposite to vitamin A, significantly (p<0.05) higher values of beta carotene in vaginal delivery compared to the surgical. In RFM affected cows the same significant (p<0.05) relationship was observed, moreover values of beta carotene were significantly (p<0.05) higher, and lower with regard to vitamin A, as compared to healthy animals. In preterm placenta beta carotene concentration was significantly (p<0.05) higher in RFM cows. Values of vitamin A showed the opposite relationship. Vitamin A and its provitamin may influence the process of fetal membrane retention.