The relationship between linoleic/linolenic acid ratio in the diet of periparturient cows, the activity of phospholipase A2, superoxide dismutase, glutathione peroxidase and thiobarbituric acid reactive substances in placental tissues at calving

The studies were undertaken on examining the influence of different linoleic/linolenic acid ratios in the diet of pregnant cows on some parameters which are involved in metabolism of prostaglandins in their placentas. Phospholipase A2 (PLA2) which provides arachidonic acid (AA), superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) the two being involved in neutralization of reactive oxygen species that appear indispensable during the metabolism of unsaturated fatty acids, thiobarbituric acid (TBA) reactive substances level, which indirectly reflects the level of peroxidative processes of unsaturated fatty acids, were all measured in the samples from the maternal and fetal part of placenta of cows fed with 2 different diets. Linoleate rich (sunflower group linoleic/linolenic acid ratio 2,22) and linolenate rich (linseed group linoleic/linolenic acid ratio 0,35) diets lasted 4 weeks before expected calving. The activity of PLA2, SOD and the content of TBA reactive substances were higher in linseed group in fetal part of placenta than in sunflower group. No significant differences were found in the maternal part of the placenta. No significant differences between experimental groups were observed according to GSH-Px activity. It is concluded that the linoleic/linolenic acid ratio in the diet may influence PLA2 activity and the level of TBA reactive substances. In result the metabolism of eicosanoids in the placenta may be modified.