Impedance Pattern of Vaginal and Vestibular Mucosa in Cyclic Goats

KŘIVÁNEK, I.: Impedance pattern of vaginal and vestibular mucosa in cyclic goats. Acta univ. agric. et silvic. Mendel. Brun., 2008, LVI, No. 4, pp. 109–114 The changes of vaginal and vestibular impedance during the oestrous cycle in goats were examined. The onset of oestrus was teased with a buck once a day during the experiment. Impedance was measured by a four-terminal method. The vaginal impedance was recorded under slight pressure of electrodes to the vaginal dorsal wall at the cervix. The vestibular impedance was recorded under slight pressure of electrodes to the vestibular dorsal wall 5 cm from the vulva and at the vulva. The im pedan ce was measured once a day from 4 days before the expected oestrus to 6 days a er onset of oestrus. The vaginal impedance at the cervix decreased during pro-oestrus (P < 0.01) and increased during oestrus (P < 0.01). The vestibular impedance 5 cm from the vulva decreased during pro-oestrus (P < 0.01) and increased a er oestrus (P < 0.01). The decrease of vaginal impedance during peri-oestrus was nearly twofold in comparison with the vestibular impedance 5 cm from the vulva. No sig nifi cant decrease of the vestibular impedance at the vulva was found during the oestrous cycle. The results indicate that the vaginal impedance at the cervix and vestibular impedance 5 cm from the vulva measured by means of a four-terminal method during the oestrous cycle display cyclic changes that are closely related to the oestrous behaviour of goats. goat, vagina, vaginal vestibule, impedance, oestrus Goats are seasonal breeders (Mori et al., 1987) and in our region the breeding season generally extends from August to January. In this period, goats come into oestrus approximately every 18 to 21 days (Matthews, 1989). For oestrus it is characteristic that the doe stands fi rmly when a buck attempts to mount (Romano et al., 1997). Another sign of oestrus is constant tail wagging from side to side. In addition, the vulva appears slightly swollen and reddened (Llewelyn et al., 1993). In spite of all these signs, it is still sometimes possible to miss oestrus. Some does may fi nd the buck sexual ly unattractive and will not stand to be bred (Pere ra et al., 1978). Similarly bucks occasionally ignore females, which appear to be in oestrus and pay more attention to higher ranking females when more than one doe is in oestrus (Llewelyn et al., 1993). A smaller proportion of does exhibits oestrus at fi rst ovulation (Chemineau, 1983; Walkden-Brown et al., 1993). Similarly oestrus detection may be more diffi cult in the absence of a buck. Oestrous does mount other does, but the frequency is low (Matthews, 1989). A number of diagnostic tools are available for monitoring events occurring during the oestrous cycle. One approach that could be suitable is the impedance technique. Cyclic changes of vaginal impedance were found in cattle (Carter and Du y, 1980; Smith et al., 1989; Řezáč and Pöschl, 1991), pigs (Řezáč and Olič, 1988; Dusza et al., 1996), sheep (Adam et al., 1981; Olič et al., 1990; Bartlewski et al., 1999), and a number of other species (Moller et al., 1984; Lilley et al., 1997; Gupta and Purohit, 2001). The main problem of this technique is the wide fl uctuation of impedance values (Peters, 1989). In the ruminants, vaginal impedance studies were concentrated mainly on cattle. On the other hand, small attention was focused on goats (Řezáč et al., 2001). The aim of this study was to determine whether the goats will show cyclic changes of vaginal impedance measured by a four-terminal method during the oestrous cycle. Simultaneously it was planned to prove whether the changes of vaginal and vestibular impedance are similar.