Cyclic changes in volatile constituents of bovine vaginal secretions.

Headspace gas chromatography was used to examine the volatile components of bovine vaginal secretions in three consecutive estrous cycles from each of four cows. Results indicated that there was an interesting peak with a retention of 2.7 min. It showed a successive rise and fall zero to three days before estrus. Gas chromatographic evidence and mass spectral data confirmed that this peak was acetaldehyde. Another unidentified compound with a retention time of 27 min was found to be unique to proestrus. It occurred two to three days prior to estrus, but was absent at any other time of the cycle.