Preliminary data on possible protein markers of parturition in cows.

Parturition is one of the most important events in reproduction. Regardless of many studies, exact time for pregnancy termination and onset of parturition is impossible to determine. The aim of this study was to describe and to compare protein profile of plasma from healthy pregnant cows (n = 6) at following five time points: 2 weeks, 1 week before, at parturition, 1 week and 2 weeks after parturition to search for possible protein markers of parturition. Plasma samples were analysed by 1D and 2D electrophoresis, and selected spots were identified by mass spectrometry. Protein profile showed no uniform pattern. Seventy spots differed at least for one sampling point from the time point 2 weeks before parturition which served as reference. Thirty spots expressed higher intensity of staining 1 week as 2 weeks before parturition while 13 showed opposite relationship. Twenty two spots expressed higher intensity of staining at parturition as 2 weeks before delivery while 15 showed opposite relationship. Eighteen spots expressed higher intensity of staining 2 weeks before parturition as 1 week post-partum while 2 showed opposite relationship. Fifteen spots expressed higher intensity of staining 2 weeks before parturition as 2 weeks after delivery while 14 showed opposite relationship. Thirty-five proteins, belonging to different functional groups, were identified. Of them, 15 spots differed significantly between parturition and 2 weeks before delivery. Among them were metalloproteinase inhibitor and LDH which seem to be the most promising molecules considered as parturition markers due to their functions.