A redução do número de doses inseminantes por fêmea coberta utilizando protocolos de uma única inseminação em tempo fixo (IATF) permitem reduzir o número de células espermáticas por fêmea coberta e otimizar os programas de inseminação artificial (IA). Considerando a grande variabilidade no intervalo entre o início do estro e a ovulação, os protocolos de IATF exigem hormonios para a sincronização da ovulação. Assim, o objetivo deste estudo foi avaliar a utilização de diferentes dosagens de hormônio luteinizante suíno (pLH) aplicado no início do estro em leitoas e porcas, através de diferentes vias de aplicação, para sincronização da ovulação e definição de um protocolo de IATF. O primeiro estudo avaliou o efeito de diferentes dosagens de pLH aplicado em leitoas no início do estro por via intramuscular (i.m.), sobre o intervalo início estro e a ovulação. Desta forma foram realizados três tratamentos: controle - sem aplicação de pLH no início do estro; pLH2,5 - uso de 2,5 mg de pLH no início do estro via i.m.; pLH5 - uso de 5 mg de pLH no início do estro via i.m. Não foram observadas diferenças no intervalo início do estro e a ovulação (IOEO) entre os diferentes tratamentos (P>0,05). De forma semelhante a distribuição de frequência do IOEO não diferiu entre os tratamentos (P>0,05). Em um segundo estudo, foi avaliado uma rota alternativa de aplicação de pLH e a performance reprodutiva de leitoas submetidas a uma única IATF. Assim, os seguintes tratamentos foram realizados: Controle - sem aplicação de hormônio no inicio do estro e realização de protocolos de múltiplas IAs; VS2.5FTAI - uso de 2,5 mg de pLH aplicado no início do estro via submucosa vulvar (v.s.) e realização de uma única IATF 16 h após; IM5FTAI - uso de 5 mg de pLH aplicado no inicio do estro via i.m. e realização de uma única IATF 16 h após. Em média foram observadas diferenças no IOEO entre os tratamentos (P<0,05) e maior frequência de leitoas ovuladas até 24 h após o inicio do estro no grupo VS2.5FTAI em relação ao grupo controle (P<0,05). A taxa de parto ajustada (AFR) não diferiu entre tratamentos (P>0,05), porém o total de leitões nascidos (TPB) foi menor no grupo VS2.5FTAI em relação ao grupo controle (P<0,05). Com objetivo de ajustar o protocolo de IATF em leitoas para uma melhor aplicabilidade prática na rotina das granjas e avaliar o uso do pLH via v.s. em porcas desmamadas, o terceiro estudo foi conduzido através de dois experimentos. Nas leitoas foram realizados dois tratamentos: controle-G - sem uso de pLH no início do estro e realização de múltiplas inseminações ao longo do estro; FTAI-G - aplicação de 2,5 mg de pLH via v.s. no início do estro e realização de uma única IATF 12 h após. O IOEO foi menor nas leitoas do grupo FTAI-G comparado ao controle-G (P<0,05), no entanto a distribuição de frequência do IOEO não foi diferente entre os tratamentos (P>0,05). A AFR foi menor para o grupo FTAI-G quando comprado ao controle-G (P<0,05). Diferenças no TPB não foram observadas entre tratamentos (P>0,05). Nas porcas desmamadas, foram realizados três tratamentos: Controle-S - sem aplicação de pLH no início do estro e realização de múltiplas inseminações; FTAI-NH - sem aplicação de pLH no início do estro e realização de uma única inseminação 24 h após; FTAI-pLH - uso de 2,5 mg de pLH no início do estro via v.s. e realização de uma única inseminação 24 h após. Os resultados deste estudo não asseguraram diferença quanto a AFR e TPB entre os distintos tratamentos (P>0,05). / The reduction in the number of semen doses used per sow served through of a single fixed-time insemination (FTAI) allows sperm cell reduction per sow served, optimising the artificial insemination (AI) programs. Considering the large variability in the interval between oestrus onset and ovulation the ovulation time, the FTAI protocols require hormones to synchronise ovulation. Thus, the aim of this study was to evaluate the use of different dosages of porcine luteinising hormone (pLH) given at oestrous onset in gilts and sows through different routes of application to synchronise the ovulation and to define a protocol of FTAI. The first study evaluated the effect of different dosages of pLH applied at oestrous onset by intramuscular route (i.m.) in gilts on interval between oestrus onset to ovulation. In this way three treatments were performed: control - without pLH application at oestrous onset; pLH2.5 - use of 2.5 mg of pLH given at oestrous onset by i.m. route; pLH5 - use of 5 mg of pLH given at oestrus onset by i.m. route. Differences in the interval onset of oestrus to ovulation (IOEO) among treatments (P>0.05) were not observed. Similarly the frequency distribution of IOEO did not differ among treatments (P>0.05). In a second study, was evaluated an alternative route of pLH application and the reproductive performance of gilts submitted to a single FTAI. Thus, the following treatments were performed: control – without pLH application at oestrous onset and use of multiple AI; VS2.5FTAI – use of 2.5 mg of pLH injected at oestrus onset by vulvar submucosal route (v.s) and use of a single FTAI 16 h later; IM5FTAI – use of 5 mg of pLH injected at oestrous onset by i.m. and use of a single FTAI 16 h later. On average differences in the IOEO among treatments (P<0.05) were observed and more VS2.5FTAI gilts ovulated up to 24 h after oestrous onset in relation to control (P<0.05). Adjusted farrowing rate (AFR) did not differ among treatments (P>0.05), however the total piglets born (TPB) was lower in the group VS2.5FTAI compared to control (P<0.05). In order to adjust the FTAI protocol in gilts for a practical use in the routine of the farm and to evaluate the use of pLH by v.s. route in weaned sows, the third study was conducted through two experiments. In gilts two treatments were performed: control-G - without pLH injection at oestrous onset and use of multiple AI during the oestrous; FTAI-G – 2.5 mg pLH applied by v.s. route at oestrous onset and use of a single FTAI 12 h later. The IOEO was shorter in the FTAI-G gilts compared to control-G (P<0.05), but the frequency distribution of IOEO did not differ between treatment (P>0.05). The AFR was lower to FTAI-G group compared to control-G (P<0.05). Differences on TPB between treatments were not observed (P>0.05). In the weaned sows three treatments were performed: control-S - without pLH application at oestrous onset and use of multiple inseminations; FTAI-NH - no hormone application and a single FTAI 24h after the onset of oestrus detection; FTAI-pLH - use of 2.5 mg pLH at oestrous onset by v.s. route and use of a single FTAI 24 h later. The results of this study did not insure difference on the AFR and TPB among treatments (P>0.05).

Thesis (MSc)--Stellenbosch University, 2004. / Full text to be digitised and attached to bibliographic record. / ENGLISH ABSTRACT: Different synchronization and superovulation treatments were evaluated in the South African Boer goat (n = 367). Two progestagen implants, Synchro-Mate-B (SMB)/Crestar™ and Controlled Internal Drug Releases (CIDR), containing 3mg norgestomet and 0.33gm of natural progesterone, respectively, were used in the synchronization treatments. A luteolytic agent, Estrumate (Cloprostenol) 125)lg, was administered 12h before progestagen withdrawal. Synchronization treatment groups were: 1) 5MB x 1 (n = 123), one dose of 5MB for 13 to 17 days; 2) 5MB x 2 (n = 32), two doses of 5MB implanted for 10then 17 days; 3) CIDR x 1 (n = 187), one dose of CIDR; 4) CIDR x 2 (n = 25), two doses of CIDR, inserted for 9 to 17 days. On day 1 of the treatment, 0.5mg of estradiol cypionate (ECP) was administered to a group of randomly chosen goats (n = 112). Superovulation treatments consisted of Ovagen ™ or Embryo-STM. An additional single dose (300 UI) of Pregnant Mare Serum Gonadotropin (PMSG) was administered to a group of randomly chosen does. Superovulation treatment groups were: 1) OV alone (n = 147), Ovagen 9 mg every 12h, 8 times starting 72h prior to progestagen removal; 2) OV + PMSG (n = 164), same treatment as 1 plus 300 ru ofPMSG once 48h prior to progestagen removal; 3) E-S alone (n=16), Embryo-S 25 units twice a day, 8 times starting 72h before progestagen removal; 4) E-S + PMSG (n=40), same treatment as 3 plus 300 ru of PMSG once 48h prior to progestagen removal. Most does were naturally bred to bucks. Embryos were collected using the surgicallaparascopic procedure on day 6 and corpora lutea counted. Data were not normally distributed and therefore analyzed using a nonparametrie test (Wilcoxon, 1945 and Kruskal- Wallis, 1952) with outcome variable using the Mixed Procedure of SAS and the Tukey test. Differences were considered significant at p<0.05. Slightly more CL were on the left (52%) than on the right (48%) ovary. Superovulation treatment was significantly associated (p<O.OOl) while synchronization treatment was only marginally associated (p=0.06) with ovulation rate. Ovagen alone and Ovagen + PMSG were significantly more effective (p<0.05) than Embryo-S alone or Embryo-S + PMSG in influencing ovulation. Only synchronization treatment with 2 doses of CIDR was significantly more (p=0.04) effective in producing a high ovulation rate. Superovulation treatment was significantly (p=0.02) associated with the number of transferable embryos while synchronization treatment was not. Ovagen + PMSG was significantly (p=0.02) effective in producing more transferable embryos than Embryo-S + PMSG. Both superovulation and synchronization treatments were significantly (p<0.05) associated with producing unfertilized oocytes. Effectiveness of addition of ECP was shown in its association (p=0.05) with better quality embryos in univaraete analysis, though it did not have significant effect in the multivariate model. Though there was apparent advantage of CIDR over 5MB, no significant difference in ovulation rate or embryo quality was associated with synchronization treatments. Effectiveness of Ovagen over Embryo-S was demonstrated and addition ofPMSG improved embryo quality. / AFRIKAANSE OPSOMMING: Verskillende sinkronisasie en multi-ovulasie behandelings is ge-evalueer in die Suid-Afrikaans Boerbok (n= 367). Twee progestagene, Synchro-Mate-B (SMB)/Crestar™ en Controlled Internal Drug Releases (CIDR), bevattende 3mg norgestomet en 0.33gm natuurlike progesteroon, respektiewelik, is gebruik tydens die sinkronisasiebehandelings. 'n Luteolitiese middel, Estrumate (Cloprostenol) 125J.lg, is toegedien 12 h voor progestageen verwydering. Sinkronisasie behandelings groepe was: 1) 5MB x 1 (n = 123), een dosis 5MB vir 13 tot 17 dae; 2) 5MB x 2 (n = 32), twee dosisse 5MB implante vir 10 tot 17 dae; 3) CIDR x 1 (n = 187), een CIDR vir die hele periode; 4) CIDR x 2 (n = 25), twee CIDRs, vir 9 tot 17 dae. Op dag 1 van die behandeling is 0.5mg estradiol cypionate (ECP) aan 'n willekeurige groep bokooie toegedien (n = 112). Multi-ovulasie behandelings het bestaan uit Ovagen™ of Embryo-S™. 'n Bykomstige dosis (300 UI) Dragtige Merrie Serum Gonadotrofien (PMSG) is toegedien aan 'n willekeurige groep ooie. Multi-ovulasie behandelingsgroepe was: 1) OV alleen (n = 147), Ovagen 9 mg elke 12h, 8 keer beginende 72 h voor progestageen verwydering; 2) OV + PMSG (n = 164), selfde behandeling as in (1) plus 300 IV PMSG eenmalig 48h voor progestageen verwydering; 3) E-S alleen (n=16), Embryo-S 25 eenhede tweemaal per dag, ag inspuitings beginende 72h voor progestageen verwydering; 4) E-S + PMSG (n=40), selfde behandeling as in (3) plus 300 IV PMSG eenmalig 48h voor progestageen verwydering. Die meerderheid ooie is natuurlik deur ramme gedek. Embrio's is gekollekteer deur gebruik te maak van die chirurgieslaparoskopiese metode op dag 6 en die aantal corpora lutea getel en aangeteken. Aangesien die data nie 'n eweredige verspreiding gehad het nie, is dit geanaliseer deur gebruik te maak van 'n nie-parametriese toets (Wilcoxon, 1945 en Kruskal-Wallis, 1952) met variërende uitkomste deur die Gemengde Prosedure Toets van SAS en die Tukey toets. Verskille is as beduidend aanvaar met 'n P-waarde van <0.05. Onbeduidend meer CLs is op die linker (52%) as op die regter (48%) ovarium opgemerk. Multi-ovuasie behandelings was beduidend geassosieer (p<0.001) met ovulasietempo, terwyl sinkronisasie behandelings net marginaal geassosieer was (p=0.06) met ovulasietempo. Ovagen alleen en Ovagen + PMSG was beduidend meer effektief (p<0.05) as Embryo-S alleen of Embryo-S + PMSG om ovulasie te beïnvloed. Slegs die sinkronisasie behandeling met 2 dosisse CIDR was beduidend meer (p=0.04) effektief om 'n hoër ovulasietempo te veroorsaak. Multi-ovulasie behandeling was beduidend geassosieer met die aantal oordraagbare embrio's, terwyl sinkronisasie nie dieselfde tendens gewys het nie. Ovagen + PMSG het beduidend meer (p=0.02) oordraagbare embrio's opgelewer as Embryo-S + PMSG. Beide multi-ovulasie en sinkronisasie behandelings was beduidend geassosieer (p<0.05) met onbevrugte oosiete. Die rol van die byvoeging van ECP is getoon in die assosiasie daarvan (p=0.05) met beter kwaliteit embrio's in 'n eenvariante analiese, alhoewel dit nie 'n beduidende effek op die multi-variante model gehad het nie. Alhoewel dit blyk dat CIDR 'n beter reaksie as 5MB gee, kon geen beduidende verskil in die ovulasietempo of embriokwaliteit opgewys word nie. Die groter effektiwiteit van Ovagen oor Embryo-S is gedemonstreer, terwyl die byvoeging van PMSG embriokwaliteit verbeter het.

Imprecise control of bovine oestrus and ovulation and the highly variable nature of the superovulatory response impedes use of reproductive technologies. The use of GnRH to control antral follicle development and, hence, the oestrous cycle was investigated using 40 maiden heifers. Two GnRH agonist sources (Fertagyl; Receptal) were tested at two frequencies (24; 48 hour) and luteinising hormone release profile; and pattern of antral follicle and luteal development were monitored. Post cessation of GnRH treatment gonadotrophin was given at either a fixed or variable time relative to oestrus and superovulatory response assessed. Basal LH values were unaffected by treatment. Treatment at 24, but not 48 hour intervals resulted in reduced LH response values. Fertagyl 24 hour treatment stimulated increased numbers of follicles to grow to 3-5 mm and 6-9 mm but inhibited growth to 10 mm, maturation and ovulation. Four waves of follicular development occurred in GnRH agonist, but not control, animals. Luteolysis and oestrus was delayed in a proportion of animals challenged with prostaglandin during GnRH agonist treatment. Exogenous gonadotrophin given at fixed time (day 10 1 where oestrus = day 0) post cessation of treatment, elicited a greater superovulatory response than when given at variable time. There was a positive relationship between number of ovulations and viable embryos; and a negative relationship between body weight and progesterone concentration and consequently superovulatory response. High superovulatory responses were observed when gonadotrophin treatment was initiated in the presence of an active corpus luteum and the absence of a dominant follicle. It was concluded that GnRH agonist given every 24 hours depleted LH reserves; allowed selection and dominance of antral follicles, but not maturation and ovulation; precluded prostaglandin induced luteolysis in some animals; and increased ovulations and embryos when gonadotrophin treatment was at a fixed time.

No description available.

The equine breeding industry continues to be somewhat inefficient, even with existing technology. On average, foaling rates are low when compared with that of other livestock. One major contributor is the inability to accurately predict ovulation in mares, which ovulate before the end of estrus, leaving much variability in coordinating insemination. A more efficient, less invasive method that could replace or reduce the need for constant teasing and ultrasonography to evaluate follicular activity is needed. In both dairy cattle and women, a change in body temperature has been shown to occur immediately prior to ovulation. Research on horses has been limited, although one study reported no useable relationship between body temperature and ovulation in mares (Ammons, 1989). The current study utilized thirty-eight mature cycling American Quarter Horse mares, and was conducted from March-August 2004. Each mare was implanted in the nuchal ligament with a microchip that can be used for identification purposes, but is also capable of reporting body temperature. Once an ovulatory follicle (>35mm) was detected using ultrasonography and the mare was exhibiting signs of estrus, the mare's follicle size and temperature were recorded approximately every six hours until ovulation. Not only was the temperature collected using the microchips, but the corresponding rectal temperature was also recorded using a digital thermometer. A significant effect (p<0.05) on body temperature was noted in relation to the presence or absence of an ovulatory follicle (>35mm) under different circumstances. When evaluating the rectal temperatures, no significant difference was found in temperature in relation to the presence or absence of a follicle. However, in the temperatures obtained using the microchip, temperature was higher (p<0.05) with the presence of a follicle of greater than 35mm. This may be due to the extreme sensitivity of the microchip implant and its ability to more closely reflect minute changes in body temperature.

<p>A series of experiments were designed to study alternative estrus synchronization and resynchronization protocols to facilitate the use of artificial insemination in cattle. </p><p>Studies were conducted to study the effects of estradiol cypionate (ECP) on follicular dynamics, time of ovulation, and pregnancy rate to timed-AI (TAI) in CIDR-based protocols. Although administration of 1 mg ECP did not result in synchronous follicular wave emergence, a dose of 0.5 mg ECP synchronized LH release and ovulation. Administration of ECP 24 h after CIDR removal resulted in acceptable pregnancy rate. However, treatment with ECP at CIDR removal resulted in acceptable pregnancy rate only if follicular wave emergence was synchronized with estradiol-17â (E-17â). </p><p>The efficacy of two estradiol preparations (5 mg of E-17â or estadiol valerate; EV) and reduced doses of EV on CL and ovarian follicular dynamics and superovulatory response were examined. When doses of 5 mg were compared, EV treatment resulted in a more variable interval to follicular wave emergence and a lower superovulatory response than E-17â. However, EV at a dose of 1 or 2 mg was efficacious in synchronizing follicle wave emergence in CIDR-treated cattle.</p><p>Pregnancy rates were compared following TAI in cattle given a new or previously used CIDR and injections of estradiol, with or without progesterone, to synchronize follicular wave emergence. Pregnancy rate following TAI did not differ between cattle treated with a new or once-used CIDR, but pregnancy rate was lower in cattle treated with one or two twice-used CIDR. The addition of an injection of progesterone to the estradiol treatment at CIDR insertion did not enhance pregnancy rate. </p><p>The efficacy of progestins (used CIDR and MGA), and E-17â, ECP, GnRH, or progesterone treatment for resynchronization of estrus in cattle not pregnant following TAI were investigated. Progestin treatment resulted in the majority of nonpregnant heifers detected in estrus over a 4-d interval. Conception rates were higher in heifers resynchronized with a once-used CIDR than with MGA. GnRH at CIDR insertion synchronized follicular wave emergence in cows, but did not increase conception rate in heifers. E-17â at CIDR insertion (1.5 mg) and removal (0.5 mg) resulted in decreased pregnancy rate following TAI. In summary, protocols described in this thesis resulted in acceptable pregnancy rates following TAI and resynchronization of previously inseminated heifers with progestins resulted in variable estrus and pregnancy rates.</p>

The purpose of the studies reported in this thesis was to provide a better understanding of the effects of purified ovulation-inducing factor (OIF) from llama seminal plasma in reflex ovulators (lama glama) and spontaneous ovulators (Bos taurus). The objective of the first study was to determine if the dose of OIF of llama seminal plasma required to elicit ovulation is physiologically relevant, and to test the hypothesis that CL form and function is affected by OIF in a dose-dependent manner. Llamas were treated with four different doses (500 £gg, 250 £gg, 125 £gg and 60 £gg) based on knowledge that for every ejaculate there is approximately 3 mg of OIF. Results supported the hypothesis that OIF affects ovulation and CL form and function in a dose-dependent manner. The high dose of OIF (500 Ýg) was associated with the highest incidence of ovulation, maximum CL diameter, plasma progesterone concentrations and plasma LH concentrations. The low dose of OIF (60 Ýg) was minimally effective for induction of ovulation and associated with smaller CL diameter and lower plasma concentrations of progesterone and LH. The second study was carried out to test the hypotheses that OIF will induce ovulation and affects CL form and function in cattle (Experiment 1), and that OIF given at different stages of development of the first follicular wave will induce atresia of the dominant follicle and hasten emergence of a new follicular wave (Experiment 2). Heifers were treated on Day 5 (Day 0 = wave emergence; Experiment 1) or on Days 3, 6 and 9 (Experiment 2) with a) 1ml of saline, b) 100 £gg of GnRH, or c) 1.0 mg purified OIF per 100 kg of body weight. Results of Experiment 1 demonstrated that OIF did not induce ovulation in cattle but it did induce atresia of the dominant follicle and earlier emergence of a new follicular wave. Results from the second study suggested that the effect previously demonstrated could be accomplished in sexually mature females after treatment on Day 6 corresponding to the late growing phase of the dominant follicle. In summary, the minimum dose of OIF necessary to induce ovulation in llamas was between 60 £gg and 250 £gg. This dose is physiologically relevant and represents less than 1/6th of what is normally present in a single llama ejaculate. In cattle OIF induced regression of the dominant follicle and early emergence of a new follicular wave in pre-pubertal heifers and had a similar effect in sexually mature heifers after treatment on Day 6 of the estrous cycle.

<p>A series of experiments were designed to study alternative estrus synchronization and resynchronization protocols to facilitate the use of artificial insemination in cattle. </p><p>Studies were conducted to study the effects of estradiol cypionate (ECP) on follicular dynamics, time of ovulation, and pregnancy rate to timed-AI (TAI) in CIDR-based protocols. Although administration of 1 mg ECP did not result in synchronous follicular wave emergence, a dose of 0.5 mg ECP synchronized LH release and ovulation. Administration of ECP 24 h after CIDR removal resulted in acceptable pregnancy rate. However, treatment with ECP at CIDR removal resulted in acceptable pregnancy rate only if follicular wave emergence was synchronized with estradiol-17â (E-17â). </p><p>The efficacy of two estradiol preparations (5 mg of E-17â or estadiol valerate; EV) and reduced doses of EV on CL and ovarian follicular dynamics and superovulatory response were examined. When doses of 5 mg were compared, EV treatment resulted in a more variable interval to follicular wave emergence and a lower superovulatory response than E-17â. However, EV at a dose of 1 or 2 mg was efficacious in synchronizing follicle wave emergence in CIDR-treated cattle.</p><p>Pregnancy rates were compared following TAI in cattle given a new or previously used CIDR and injections of estradiol, with or without progesterone, to synchronize follicular wave emergence. Pregnancy rate following TAI did not differ between cattle treated with a new or once-used CIDR, but pregnancy rate was lower in cattle treated with one or two twice-used CIDR. The addition of an injection of progesterone to the estradiol treatment at CIDR insertion did not enhance pregnancy rate. </p><p>The efficacy of progestins (used CIDR and MGA), and E-17â, ECP, GnRH, or progesterone treatment for resynchronization of estrus in cattle not pregnant following TAI were investigated. Progestin treatment resulted in the majority of nonpregnant heifers detected in estrus over a 4-d interval. Conception rates were higher in heifers resynchronized with a once-used CIDR than with MGA. GnRH at CIDR insertion synchronized follicular wave emergence in cows, but did not increase conception rate in heifers. E-17â at CIDR insertion (1.5 mg) and removal (0.5 mg) resulted in decreased pregnancy rate following TAI. In summary, protocols described in this thesis resulted in acceptable pregnancy rates following TAI and resynchronization of previously inseminated heifers with progestins resulted in variable estrus and pregnancy rates.</p>

The purpose of the studies reported in this thesis was to provide a better understanding of the effects of purified ovulation-inducing factor (OIF) from llama seminal plasma in reflex ovulators (lama glama) and spontaneous ovulators (Bos taurus). The objective of the first study was to determine if the dose of OIF of llama seminal plasma required to elicit ovulation is physiologically relevant, and to test the hypothesis that CL form and function is affected by OIF in a dose-dependent manner. Llamas were treated with four different doses (500 £gg, 250 £gg, 125 £gg and 60 £gg) based on knowledge that for every ejaculate there is approximately 3 mg of OIF. Results supported the hypothesis that OIF affects ovulation and CL form and function in a dose-dependent manner. The high dose of OIF (500 Ýg) was associated with the highest incidence of ovulation, maximum CL diameter, plasma progesterone concentrations and plasma LH concentrations. The low dose of OIF (60 Ýg) was minimally effective for induction of ovulation and associated with smaller CL diameter and lower plasma concentrations of progesterone and LH. The second study was carried out to test the hypotheses that OIF will induce ovulation and affects CL form and function in cattle (Experiment 1), and that OIF given at different stages of development of the first follicular wave will induce atresia of the dominant follicle and hasten emergence of a new follicular wave (Experiment 2). Heifers were treated on Day 5 (Day 0 = wave emergence; Experiment 1) or on Days 3, 6 and 9 (Experiment 2) with a) 1ml of saline, b) 100 £gg of GnRH, or c) 1.0 mg purified OIF per 100 kg of body weight. Results of Experiment 1 demonstrated that OIF did not induce ovulation in cattle but it did induce atresia of the dominant follicle and earlier emergence of a new follicular wave. Results from the second study suggested that the effect previously demonstrated could be accomplished in sexually mature females after treatment on Day 6 corresponding to the late growing phase of the dominant follicle. In summary, the minimum dose of OIF necessary to induce ovulation in llamas was between 60 £gg and 250 £gg. This dose is physiologically relevant and represents less than 1/6th of what is normally present in a single llama ejaculate. In cattle OIF induced regression of the dominant follicle and early emergence of a new follicular wave in pre-pubertal heifers and had a similar effect in sexually mature heifers after treatment on Day 6 of the estrous cycle.

The equine breeding industry continues to be somewhat inefficient, even with existing technology. On average, foaling rates are low when compared with that of other livestock. One major contributor is the inability to accurately predict ovulation in mares, which ovulate before the end of estrus, leaving much variability in coordinating insemination. A more efficient, less invasive method that could replace or reduce the need for constant teasing and ultrasonography to evaluate follicular activity is needed. In both dairy cattle and women, a change in body temperature has been shown to occur immediately prior to ovulation. Research on horses has been limited, although one study reported no useable relationship between body temperature and ovulation in mares (Ammons, 1989). The current study utilized thirty-eight mature cycling American Quarter Horse mares, and was conducted from March-August 2004. Each mare was implanted in the nuchal ligament with a microchip that can be used for identification purposes, but is also capable of reporting body temperature. Once an ovulatory follicle (>35mm) was detected using ultrasonography and the mare was exhibiting signs of estrus, the mare's follicle size and temperature were recorded approximately every six hours until ovulation. Not only was the temperature collected using the microchips, but the corresponding rectal temperature was also recorded using a digital thermometer. A significant effect (p<0.05) on body temperature was noted in relation to the presence or absence of an ovulatory follicle (>35mm) under different circumstances. When evaluating the rectal temperatures, no significant difference was found in temperature in relation to the presence or absence of a follicle. However, in the temperatures obtained using the microchip, temperature was higher (p<0.05) with the presence of a follicle of greater than 35mm. This may be due to the extreme sensitivity of the microchip implant and its ability to more closely reflect minute changes in body temperature.