Intravaginal impedance and sexual behavior of ovariectomized goats given estrogen alone, or in combination with, progesterone

¹ Department of Animal Sciences, Rutgers, The State University of New Jersey, 84 Lipman Drive, New Brunswick, NJ, 08901-8525
² Institute of Animal Science, The Volcani Center, (Agricultural Research Organization) Bet-Dagan 50250, Israel

^* To whom correspondence should be addressed. E-mail: katz{at}aesop.rutgers.edu.

	Abstract

Intravaginal impedance (IVI) fluctuates during the goat estrous cycle. To understand which ovarian steroids are responsible for IVI changes and whether IVI variations are associated with pre-copulatory and copulatory behaviors, 8 ovariectomized females were assigned to 4 treatments in a 4 x 4 Latin square replicated over four, 8-d periods. The treatments were: progesterone plus estradiol-17 (P + E2), oil plus estradiol-17 (E2), progesterone plus oil (P), or oil (OIL). Daily IVI measurements at the vagino-cervical junction were taken at 1 and 70 KHz. Progesterone was given on d 2 and 3. Estradiol was given in the evening of d 5. On d 1 to 8, goats were group-exposed to a sexually experienced male and observed for expression of sexual behaviors. On d 6 and 7 IVI was less when goats received P + E2 or E2, compared with goats given P or OIL (P < 0.05). Impedance measured at 1 kHz tended to remain lower on d 8 in P + E2-treated females compared with those given P or OIL (P < 0.055). Like previous results, P + E2 or E2 treatment induced behavioral estrus; 5 of 8 P + E2-treated and 5 of eight E2-treated females were receptive on d 6. Although IVI remained low on d 7 and 2/8 P + E2-treated goats and 4/8 E2-treated goats remained receptive, no additional females were in estrus. No IVI decreases and no estrous behavior were observed in goats given P or OIL. This experiment demonstrated that E2 initiates the peri-estrous drop in IVI and P may delay baseline return.

Key Words: Estrogen, estrus, goat, impedance, progesterone, vagina