Academic literature on the topic 'Ovulation synchronization'

Two experiments tested the efficacy of gonadotropin-releasing hormone (GnRH) or estradiol cypionate (ECP) administration in combination with controlled internal drug release (CIDR) inserts on pregnancy rate to fixed-time artificial insemination (FTAI) in beef heifers. In the first experiment, heifers in the two ECP groups received ECP in conjunction with the CIDR insert. The CIDR insert was removed and PGF was administered on either d 7 or 9. Heifers received ECP 24 h after CIDR removal and were inseminated 30 h after ECP. Heifers in the two GnRH groups received GnRH in conjunction with the CIDR insert. Heifers received PGF on either d 6 or 7, and the CIDR insert was removed on d 7. Heifers were inseminated and received GnRH 48 h after CIDR removal. Pregnancy rates to FTAI were higher for heifers treated with GnRH. Pregnancy rate to FTAI was highest for heifers in the GnRH group that received PGF on d 6 and was lowest for the group that received ECP in combination with a 7-d CIDR insert. In the second experiment, heifers received GnRH in conjunction with the CIDR insert. CIDR inserts were removed and PGF was administered on d 7. Heifers were inseminated 60 h later, with one group receiving GnRH at insemination. Pregnancy rate to FTAI was higher for heifers that received GnRH at insemination. The final experiment tested the efficacy of estradiol 17_ (E17) or GnRH in combination with a CIDR insert on pregnancy rate to FTAI in Brahman cows. Either E17 or GnRH was administered in conjunction with the CIDR insert. CIDR inserts were removed on d 7. Cows in the GnRH group received PGF on d 6 and GnRH at insemination which occurred 48 h after CIDR removal. Cows in the E17 group received PGF on d 7, E17 24 h later, and were inseminated 30 h after E17 administration. Pregnancy rate to FTAI was higher for cows treated with E17. These data indicate acceptable pregnancy rates were obtained when the CIDR insert was combined with either GnRH in beef heifers or with E17 in Brahman cows.

Two experiments were conducted to determine efficacy of GnRH analogs, Cystorelin (CYS, gonadorelin diacetate tytrahydrate) and Factrel (FAC, gonadorelin hydrochloride), for use in beef timed AI synchronization. In Experiment one 342 beef cows from 7 herds were assigned CYS or FAC treatment as part of the Ovsynch protocol (GnRH d 0 and 9, Lutalyse d 7). Cattle treated with FAC had greater tendency (P=.09) to be pregnant at d 45. One individual herd demonstrated FAC-treated cows had more pregnancies at day 45. In Experiment two, 18 beef cows received either CYS or FAC as part of the Ovsynch protocol, intensive blood samples, from time -30 to 525 min post GnRH, were collected at each GnRH injection. Ultrasounds were conducted daily over the course of the protocol. A treatment by phase interaction (P=.03) was found for the time to maximum LH concentration, where CYS-treated follicular cows had a shorter interval than did FAC treated follicular or luteal cows. The duration of detectable LH response showed a treatment by phase interaction (P = .02) where follicular and luteal CYS-treated cows had shorter interval than follicular or luteal FAC-treated cows. The variables maximum LH concentration, and area under LH curve did not differ. Cows treated with CYS had more (P=.02) non-dominant follicles. In Experiment three, 16 ewes randomly received either CYS, FAT or Fertagyl (FER; gonadorelin diacetaate tytrahydrate), and FAT's induced LH maximum concentration occurred sooner (P=.02) than CYS. We conclude that either product may be used in beef cows without compromising fertility.<br>Master of Science

Physiological stressors of high milk production and intensive management systems affect fertility and pregnancy rates (PR) in lactating dairy cows. A field study was conducted on dairy farms in the Fraser Valley of British Columbia to benchmark current reproductive performance and issues that impact local dairy farms. The results indicated a substantial reduction in reproductive performance due to inaccurate estrus detection, fertilization/ovulation failure, and embryonic mortality. Ovsynch timed artificial insemination (TAI) protocol is used for the induction and synchronization of ovulation in cattle, reducing the need for estrus detection. However, PR to Ovsynch TAI are still low. Strategies to modify Ovsynch TAI protocol were investigated in this study to increase PR. In the first experiment, Ovsynch was compared with a pre-synchronization treatment, using PGF₂α before Ovsynch TAI to improve synchronization rates, and to a treatment of GnRH given 6 d after Ovsynch TAI, to reduce embryonic loss. Although no differences in PR were observed between treatments, days in milk in cows and age and weight in heifers affected PR. In the second experiment, the effects of pLH or hCG vs. GnRH in an Ovsynch TAI protocol were compared. Progesterone concentrations in pregnant cows were greater in the hCG group on days 7, 11, and 14, and greater in the pLH group on day 11 after breeding than GnRH group. There were no differences in synchronization rates or PR between treatments. High protein diets have been associated with reduced PR. Therefore, in the third experiment, cows either continued on a typical high protein diet, which was fed from calving, or switched to a lower protein diet, beginning 7 d before Ovsynch TAI and continued until pregnancy diagnosis. First and second lactation cows fed the low protein diet tended to have greater PR than cows fed the high protein diet. There were no differences in synchronization rates and progesterone concentrations between diets. Cows fed the lower protein diet had lower milk urea nitrogen and lower average daily milk production during treatment. Costs associated with treatments, labour, and producer compliance should be considered before recommending ovulation synchronization Ovsynch TAI protocol to dairy producers.

Thesis (MSc)--Stellenbosch University, 2004.<br>Full text to be digitised and attached to bibliographic record.<br>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.<br>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.

Doctor of Philosophy<br>Department of Animal Sciences and Industry<br>Jeffrey S. Stevenson<br>Two experiments assessed pregnancy outcomes (pregnancy per AI; P/AI) after 5-d Ovsynch-56 Resynch (RES; GnRH injection 5 d before [GnRH-1; d 0] and 56 h (GnRH-2) after the last PGF2α [PGF] injection on d 6 given 24 h after first PGF injection on d 5, and TAI on d 8) with and without a 5-d progesterone insert. In Exp. 1, only 76% of 1,023 nonpregnant cows enrolled on d 34 post-AI had high (≥1 ng/mL) progesterone. The RES-CIDR cows with low progesterone at treatment initiation had greater P/AI than RES-CON (37.7 vs. 29.4%), whereas RES-CIDR cows with high progesterone had lesser P/AI than RES-CON (27.4 vs. 34.3%) suggesting that supplemental progesterone is progesterone-dependent. In Exp. 2, 381 cows were enrolled in similar treatments on d 31 with RES on d 41post-AI plus a third treatment including PG-3-G (Pre-PGF on d 31, Pre-GnRH on d 34, and RES on d 41. The P/AI was similar among treatments but was greater in cows starting RES on d 41 when progesterone was low (44%) than high (33%).Experiment 3 determined LH and ovulatory responses in cows enrolled in two treatments before AI: 1) Pre10 (n = 37): PGF-1 and PGF-2 given 14 d apart (Presynch); or PG3G (n = 33): PGF given concurrent with the PGF-2, 3 d before GnRH-1 followed in 7 d by Ovsynch [injection of GnRH (GnRH-2) 7 d before PGF (PGF-3) and GnRH-3 at either 56 or 72 h after PGF-3] that was initiated 10 d after PGF-2 for Pre10 or 7 d after GnRH-1 of PG3G. The GnRH- 1 increased incidences of LH surges and ovulation in PG3G compared with Pre10. The LH in serum of Pre10 was greater than that of cows receiving PG3G after GnRH-2. Following GnRH- 3, cows receiving GnRH at 72 h had increased incidence of spontaneous LH surges before GnRH-3. The P/AI for PG3G vs. Pre10 and for 56 vs. 72 h was similar, but the Pre10-72 h treatment combination was less than all other treatment combinations. Release of LH is protocol dependent and flexibility of GnRH timing is an advantage for PG3G before first-service TAI.

Foram realizados cinco experimentos com o objetivo de sincronização do estro e indução da ovulação em tempo fixo em éguas. Experimento I: avaliou a eficácia de um novo protocolo hormonal para a sincronização do estro, sendo realizado durante o período transicional em éguas cujo status reprodutivo era desconhecido. Experimento II: foi delineado para determinar o momento ideal para retirada dispositivo intravaginal de progesterona (DIP), sendo o dispositivo retirado no dia 7, 8 ou 9 do protocolo de tratamento hormonal. Experimento III: testou se a eficiência do protocolo é dependente da fase do ciclo estral da égua e definiu o melhor momento para indução da ovulação. Experimentos IV e V: as éguas foram submetidas ao protocolo completo de sincronização da onda folicular e indução da ovulação em diferentes fases do ciclo estral ou com status reprodutivo conhecido. A hipótese testada foi de que a sincronização do estro e indução da ovulação, com o uso do DIP de 1,44g provoca a supressão do crescimento folicular e através da indução da ovulação, com hCG e GnRH, promove a ovulação dentro de 42 ± 6 horas de no mínimo 75% dos animais. Para isso, os efeitos das prostaglandinas e progestágenos foram avaliados quanto à capacidade de sincronizar a onda de crescimento folicular. Um novo tratamento para induzir a ovulação em tempo fixo foi testado com uma combinação de GnRH e hCG em dois momentos estratégicos (D10 e D12) visando maximizar o número de éguas ovuladas. O protocolo com administração de prostaglandina no D0, D6 e D8 juntamente com a colocação do DIP mantido durante 8 dias (D0 ao D7) demonstrou ser eficaz para suprimir a taxa de crescimento folicular em éguas cíclicas. Nas éguas submetidas a este protocolo as ovulações que ocorreram naturalmente se concentraram entre os dias 10 e 13 do tratamento. Foi testada a eficiência da indução da ovulação no D10 e D12. Na maioria dos animais tratados, o folículo pré-ovulatório foi responsivo à combinação de GnRH e hCG promovendo o sucesso da indução da ovulação. A eficiência do protocolo hormonal testado para sincronização do estro e da ovulação foi de 76,73%, sustentando a hipótese deste estudo. Novos estudos devem ser realizados em um maior número de animais para possíveis adequações na terapia hormonal e verificação do resultado em um grande número experimental de animais.<br>Five experiments were conducted with the objective of estrus synchronization and fixed time ovulation induction in mares. Experiment I: evaluated the efficacy of a new hormonal protocol for estrus synchronization in mares whose reproductive status was unknown during the transitional period. Experiment II: was designed to determine the best time to remove the P4 intravaginal device (PID). The device was removed on day 7, 8 or 9 of the hormonal treatment protocol. Experiment III: tested if protocol efficiency depends on the stage of mares estrus cycle and indicated the best time for hormonal induction of ovulation. Experiments IV and V: mares were submitted to the full protocol of follicular wave synchronization and ovulation induction at different stages of estrus cycle or at known reproductive status. The tested hypothesis was that the estrus synchronization and induction of ovulation, using an PID of 1.44g, causes suppression of follicular growth, and ovulation induction using hCG and GnRH promote ovulation within 42 ± 6 hours of at least 75% of treated animals. The effect of prostaglandin and progestagens at specific times were evaluated for the ability to synchronize follicular wave. A new treatment to induce fixed time ovulation was tested with GnRH and hCG combination in two strategic moments (D10 and D12) to maximize the number of ovulated mares. Administration of prostaglandin at D0, D6 and D8 together with PID maintained for 8 days (D0 to D7) proved to be effective to suppress follicular growth during reproductive period. In mares submitted to this protocol, ovulation occurred naturally and concentrated between D10 and D13. The ovulation induction efficiency was tested at D10 and D12. Most of the animals had preovulatory follicle responsiveness to GnRH and hCG, promoting the success of ovulation induction. The efficiency of the tested synchronization of estrus and ovulation induction protocol was 76.73% and supported the hypothesis of this study. Further studies should be performed on a larger number of animals for possible adjustments in hormonal therapy and verification of the result in a large number of animals.

Objectives were to 1) evaluate the use of the CO-Synch + CIDR (COS-C) protocol for synchronization of ovulation and timed AI (TAI) in Bos indicus-influenced cattle, 2) compare cumulative pregnancy rates after COS-C synchronization and TAI to those in a traditional management (TM) scheme, and 3) evaluate specific ovarian, hormonal, and estrual events associated with COS-C. The COS-C regimen included insertion of a controlled internal drug release device (CIDR) containing progesterone and injection of GnRH (GnRH-1) on day 0, removal of the CIDR and injection of prostaglandin F2a (PGF on d 7, and injection of GnRH (GnRH-2) and TAI 48 h later. In experiment 1 (Exp. 1), 335 females were stratified by BCS, parity and d postpartum before random assignment to COS-C or TM. An additional 96 females in which TM controls were not available for comparison also received COS-C. Conception rates to TAI averaged 39% (n = 266). Cumulative pregnancy rates were greater (P < 0.05) after 30 and 60 d of the breeding season in COS-C than in TM (n = 170 and 165 females respectively). In experiment 2 (Exp. 2), 100 postpartum (F1) females were stratified as in Exp. 1 within four replicates (25 each) and assigned randomly to receive either COSC or COS (no CIDR) treatment. No differences were observed between treatments and all data were pooled. Percentages of cows ovulating after GnRH-1, developing a synchronized follicular wave, exhibiting luteal regression to PGF, and ovulating to GnRH-2 were 40, 60, 93, and 72%, respectively. In experiment 3 (Exp. 3), primiparous (F1) heifers (n = 32) and pluriparous cows (n = 18) received the Select Synch + CIDR synchronization regimen (no GnRH-2 or TAI). Mean intervals from CIDR removal to estrus and ovulation, and from estrus to ovulation were 70 ± 2.9, 99 ± 2.8, and 29 ± 2.2 h, respectively. Relatively low TAI conception rates (< 50%) were attributed to failure of 40% of cattle to develop a synchronized follicular wave after GnRH-1 and to inappropriate timing of TAI/GnRH-2. It may be possible to improve TAI conception rates by delaying TAI/GnRH-2 to between 66 and 72 h, and by developing methods to increase the number of ovulations after GnRH-1.

CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel Superior<br>Avaliou-se a eficiÃncia de dois protocolos de induÃÃo e sincronizaÃÃo do estro e da ovulaÃÃo (âCIDR-Bâ âOVSYNCHâ) em 90 novilhas acÃclicas da raÃa Girolanda. Os animais foram distribuÃdos em trÃs grupos, onde o primeiro (n=30) foi submetido ao protocolo âOVSYNCHâ, que consiste na aplicaÃÃo intramuscular (IM) de 1,0ml de GnRH, sete dias depois 2,0ml de prostaglandina F2a (PGF2a), 48h depois mais 1,0ml de GnRH e IATF 16h apÃs a segunda dose de GnRH. O segundo grupo (n=30) foi submetido ao tocolo âCIDR-Bâ, que consiste na introduÃÃo do implante intravaginal âCIDR-Bâ juntamente com a aplicaÃÃo IM de 2,0ml de benzoato de estradiol (BE), apÃs 8 dias à feita a remoÃÃo do âCIDR-Bâ e a aplicaÃÃo IM de 500UI de gonadotrofina sÃrica da Ãgua prenhe (PMSG) e 2,0ml de PGF2a, 24h apÃs à feita mais uma aplicaÃÃo IM de BE e IATF 30h depois desta aplicaÃÃo, ou seja, 54h apÃs a remoÃÃo do âCIDR-Bâ. O rceiro grupo (n=30), grupo controle, nÃo foi submetido a tratamento hormonal. Os diagnÃsticos de gestaÃÃes foram feitos 35 dias apÃs a primeira, segunda e terceira nseminaÃÃes artificiais (IA) por meio de ultra-sonografia (US). TambÃm foi avaliado o custo/benefÃcio de cada protocolo. O tratamento âCIDRBâ mostrou-se mais eficiente em primeira IA (p<0,05), assemelhando-se ao grupo controle com taxas de concepÃÃo e prenhez de 60 e 50%, respectivamente, demonstrando ter uma qualidade de estro comparÃvel ao natural. Na segunda IA, os tratamentos foram equivalentes nas taxas de prenhez, mas diferiram nas de concepÃÃo (96% âCIDR-Bâ e 76% âOVSYNCHâ). Deste modo, o protocolo âCIDR-Bâ mostrouse mais eficiente na induÃÃo da puberdade em novilhas girolandas com melhores taxas de concepÃÃo e prenhez em primeira IA, reduzindo onsideravelmente a idade ao primeiro parto. AlÃm disso, apresenta-se economicamente viÃvel com possibilidade de reutilizaÃÃo do implante, devendo-se atentar aos cuidados com higiene e manipulaÃÃo do produto.<br>Two oestrus and ovulation synchronization protocols (CIDR-B and OVSYNCH) were tested on 90 acyclical Girolanda heifers. The animals were distributed in three groups. Group I (n=30) was submitted to the OVSYNCH protocol, consisting of: intramuscular (IM) application of 1.0 ml gonadotropin-releasing hormone (GnRH), 2.0 ml rostaglandin F2a (PGF2a) after 7 days, 1.0ml GnRH 48h later, then timed artificial insemination (TAI) 16h after the second application of GnRH. Group II (n=30) was submitted to the CIDR-B protocol, consisting of: introduction of intravaginal CIDR-B implant and application of 2.0 ml estradiol benzoate (EB) IM, implant removal after 8 days, application of 500 UI pregnant mare serum gonadotropin (PMSG) and 2.0 ml PGF2a, a second IM application of BE 24h subsequently, then TAI 30h later (i.e. 54h following implant removal). Group III (n=30; control group) received no hormonal treatment. Gestation was verified ltrasonographically 35 days after the first, second and third AI. The cost-benefit ratio of each protocol was also determined: The CIDR-B protocol was most efficient in the first AI in which it was comparable to the control group in providing a near-natural oestrus quality (conception and pregnancy rates of 60% and 50%, respectively; p<0.05). In the second AI, the two treatments yielded similar pregnancy rates, but differed in conception rates (96% for CIDR-B; 76% for OVSYNCH). Thus the CIDR-B protocol was the more efficient in inducing puberty in Girolanda heifers, featuring the best conception and pregnancy rates in the first AI and considerably reducing age at first birth. It is moreover economically feasible as the implant may be reused provided apropriate care is given to hygiene and handling.