Changes of vaginal and vestibular impedance in dairy goats during the estrous cycle

Abstract

The changes of vaginal and vestibular impedance during the estrous cycle in goats were evaluated. The impedance technique is one of the tools that could be used for non-invasive monitoring of events occurring in cyclic animals. In September the onset of estrus was monitored throughout the experiment with the buck introduced to does twice a day. Impedance was measured by a two-terminal method. The vaginal impedance was recorded under slight pressure of electrodes to the vaginal dorsal wall close to the cervix. The vestibular impedance was recorded under slight pressure of electrodes to the mucosa of the left side of the vaginal vestibule, 4 cm from the vulva and near the vulva. The impedance was measured once daily from 5 days before the expected estrus to 8 days after onset of estrus. The vaginal impedance near the cervix decreased gradually ( P<0.01) to the estrus onset and increased after manifestation of estrus ( P<0.01). The vestibular impedance 4 cm from the vulva significantly decreased during proestrus and increased during estrus. The decrease of vaginal impedance during peri-estrus was nearly two-fold in comparison with the vestibular impedance 4 cm from the vulva. There was no significant decrease in the vestibular impedance near the vulva during the estrous cycle. The results suggest that the vaginal impedance near the cervix and vestibular impedance 4 cm from the vulva measured by means of a two-terminal method during estrous cycle display cyclic changes that are closely related to the estrous behavior of goats.