The effectiveness of PGF2α HCG and GnRH for appointment breeding of mares

Advancing the time of ovulation in the mare with a short‐term implant releasing the GnRH analogue deslorelin

“…Timing of ovulation in oestrous mares is a highly desirable goal for the equine breeding industry, in which artificial insemination with fresh, cooled or frozen semen is increasingly in demand and unnecessary inseminations are costly, as is the wasting of stallion power. While pharmacological control of the oestrous cycle has been achieved (Palmer and Jousset 1975;Holtan et al 1977;Bums et al 1979;Loy et al 1979Loy et al , 1981Hyland and Bristol 1979;Palmer 1979;Allen et al 1980;Martin et al 1981;Squires et al 1981a;Harrison et al 1991), control of ovulation time during the induced or synchronised oestrus has been less successful (Bums et al 1979;Loy et al 1979;Hyland and Bristol 1979;Palmer 1979;Allen et al 1980;Martin et al 1981;Squires et al 1981;Harrison et al 1991). In regularly cycling mares, hCG, GnRH or its analogues, and PGF2, or its analogues have been used to accelerate ovulation during Oestrus.…”

“…Single treatments with GnRH required high doses and the responses were inconsistent (Ginther and Wentworth 1974;Garcia and Ginther 1975;Heinze and Klug 1975;Irvine 1975;Roser et al 1980;Michel and Rossdale 1986;Palmer and Quellier 1988). Starting with 35 mm follicles, 3.6 to 3.8 injections with the potent GnRH analogue buserelin, 40 pg per treatment every 12h, were needed to provide ovulations at 48 h after treatment started (Squires et al 1981a). PGF analogue treatments for acceleration of ovulation are popular with many veterinarians.…”

Efficacy of human chorionic gonadotrophin and gonadotrophin releasing hormone for hastening ovulation in Thoroughbred mares

“…Reports on the use of gonadotrophin releasing hormone (GnRH) in the mare, as an alternative t o hCG, have appeared more recently and with conflicting results. It has been found that GnRH, given as a single injection on the second day o f : spontaneous oestrus (Ginther and Wentworth 1974); oestrus following treatment with prostaglandin (PG) F l u (Oxender, Noden and Pratt 1977;Squires et a/ 1981) and; oestrus following treatment with progesterone (Pope, Campbell and Davidson 1979), did not advance follicular development and ovulation. Irvine, Downey, Parker and Sullivan (1975) found that a single intravenous or subcutaneous injection of GnRH analogue (AY-2403 1 ; Ayerst Laboratories), given on the second day of oestrus, did not hasten ovulation but was effective if given daily.…”

Attempts to Synchronize Estrus and Ovulation in Mares Using Progesterone (CIDR‐B) and GnRH‐Analog Deslorelin

“…The precise control of the estrous cycle, especially of ovulation, is an unresolved problem in equine reproduction (Palmer and Jousset 1975;Hyland and Bristol 1979;Loy et al 1979;Palmer 1979;Squires et al 1979;Voss et al 1979;Dinger et al 1981;Martin et al 1981;Squires et al 1981;Draincourt and Palmer 1982;Palmer et al 1984;Palmer 1985;Ashbury 1989), as well as the reliable induction of follicle growth, maturation and ovulation in acyclic mares during the breeding season not due to a persisting corpus luteum (CL) (Reiner and Jochle 1981;Howey et al 1983). In addition, methods of inducing reliably fertile ovulations during the autumn/winter anestrus season are lacking (Ginther 1992).…”

“…In addition, methods of inducing reliably fertile ovulations during the autumn/winter anestrus season are lacking (Ginther 1992). For the control of estrus, progestins, either alone (Hyland and Bristol, 1979;Voss et al 1979;Draincourt and Palmer, 1982) or in combinations with estradiol (Burns and Douglas 1979;Douglas 1981, Loy et al 1982;Burns et al 1990;Jasko et al 1993;Blanchard et al 1992), as well as either PGF (Palmer and Jousset 1975;Loy et al 1981;Martin et al 1981;Squires et al 1981;Palmer, 1985;Ashbury, 1989) or GnRH (Squires et al 1981) have been widely used. These methods have resulted in the synchronization of estrus, but have failed to synchronize ovulation.…”