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1.
The aim of this study was to investigate characterization of oestrous response, onset of induced oestrus, oestrous duration, fecundity and fertility in Awassi ewes treatment with intravaginal sponges and Controlled Intravaginal Drug Release (CIDR) devices in combination with pregnant mare serum gonadotropin (PMSG) under local environmental conditions during the non‐breeding season. A total of 62 ewes were divided into three groups. Group CIDR (n = 20) was treated with CIDR devices for 12 days and 400 IU PMSG was injected upon removal of the CIDR. For ewes in Group Sponge (SP) (n = 24), 30 mg fluorogestone acetate was administered to the sheep for 12 days and 400 IU PMSG was injected upon withdrawal of the sponge. Group Control (CON) (n = 18) served as a control group and received no treatment. Adult, intact and sexually experienced Awassi rams were introduced to all groups at the time when the intravaginal devices were removed. There were no significant differences in terms of oestrous response (CIDR: 90%, SP: 87.5%), time to onset of oestrus and duration of induced oestrus between the CIDR and SP groups. The oestrous response of treatment groups was significantly greater (p < 0.05) than in the control ewes. There were no significant differences in pregnancy (CIDR: 70%, SP: 70.8%), lambing (CIDR: 85%, SP: 79.2%) and fecundity rates between ewes treated with CIDR and those treated with sponges. However, pregnancy and lambing rates were significantly (p < 0.05) higher in ewes treated with CIDR or sponges when compared with those in the control group. It was concluded that it is possible to induce fertile oestrus, successful pregnancy and lambing with the treatment of either CIDR or intravaginal sponge in combination with PMSG in Awassi ewes during the non‐breeding season.  相似文献   

2.
The present study aimed to investigate the fertility of ewes artificially inseminated with three different methods using a synthetic semen extender, AndroMed. The three methods of artificial insemination (AI) were cervical AI with fresh-diluted or frozen-diluted semen at observed estrus, and an intrauterine AI with frozen-thawed semen. A total of 80 ewes were treated with a controlled internal drug release (CIDR) containing 0.3 g progesterone per device for 12 days. In Experiment 1 (26 Suffolk ewes), superovulation was induced with 20 mg follicle-stimulating hormone and 250 IU equine chorionic gonadotropin (eCG) two days and one day before CIDR removal, respectively, during the non-breeding season. In Experiment 2 (54 Suffolk and Suffolk crossbred ewes), an intramuscular injection of 500 IU eCG was administered one day before CIDR removal to synchronize estrus and ovulation during the breeding season. In Experiment 1, fresh-diluted or frozen-thawed semen was deposited into the cervical orifice after estrus detection, and an intrauterine AI with frozen-thawed semen was performed by laparoscopy at a fixed-time basis without estrus detection. Embryos were recovered by uterine flushing 6 days after AI, and the rates of recovered, fertilized (cleaved) ova and embryos at the morula or blastocyst stage were compared among the three AI methods. In Experiment 2, the pregnancy rates after the three AI methods were compared. In Experiment 1, the rates of recovered ova were not significantly different among the three AI methods (52.5-56.7%). The rate of fertilized ova (81.0%) by laparoscopic AI with frozen-thawed semen was significantly higher compared with cervical AI of fresh-diluted (25.5%) or frozen-thawed (3.5%) semen, but the rate of embryos at the morula or blastocyst stage (17.6%) was significantly lower than that of the cervical AI with fresh-diluted semen (69.2%). The rates of ewes yielding fertilized ova were not significantly different among the three groups (44.4, 11.1 and 62.5% for cervical AI with fresh-diluted and frozen-thawed semen and intrauterine AI with frozen-thawed semen). In Experiment 2, the pregnancy rate of ewes intrauterinally inseminated with frozen-thawed semen (72.2%) was significantly higher than those of ewes inseminated cervically with fresh-diluted (5.5%) or frozen-thawed (0.0%) semen. The present results showed that acceptable fertilization and pregnancy rates could be obtained by an intrauterine AI with frozen-thawed semen using a synthetic semen extender (AndroMed), but not sufficient by the cervical AI with either fresh or frozen semen.  相似文献   

3.
Traditional treatments of two prostaglandin F2 alpha (PGF2alpha) doses at 10-day intervals or more did not result in acceptable pregnancy rates in timed artificial insemination (TAI) programmes in ewes. An explanation might be the undefined time-period of the onset of oestrus and ovulation after the treatment. Recently a consistent interval to oestrus and ovulation was obtained by giving PGF2alpha at day 3 post-ovulation, i.e. when the largest follicle of the first follicular wave of the cycle was still growing. This can be achieved when a second dose of PGF2alpha is given 7 days after a first dose. In this work, we evaluated the synchronization of oestrus and determined which of three different moments of TAI was the most successful using a PGF2alpha (PG-7d) protocol in a large flock. A total of 436 nulliparous and multiparous ewes were treated with two doses of a PGF2alpha analogue (delprostenate 160 microg, i.m.) separated by 7 days. Onset of oestrus was recorded twice a day and a single cervical TAI with fresh undiluted semen was performed either at 42 h (n = 152), 48 h (n = 120), or 54 h (n = 164), after the second PGF2alpha dose without taking into account the oestrous response. Pregnancy rate was determined by transrectal ultrasonography 30 days after insemination. Onset of oestrus was detected in 308 of 328 and 89 of 108 multiparous and nulliparous ewes, respectively (p < 0.001), within 72 h after treatment. The distribution of the onset of oestrus did not differ between multiparous and nulliparous ewes and the highest proportion of ewes in oestrus was detected between 25 to 48 h (313/397) from the second PGF2alpha dose. The pregnancy rate in ewes inseminated at 42 h tended to be higher than those inseminated at 48 h (p = 0.09) and was higher than those inseminated at 54 h (p < 0.05) (56/152, 31/120, 37/164; respectively). Therefore, the use of the PG-7d protocol resulted in a very high synchronization of oestrus with the highest concentration (around 80%) between 25 to 48 h from the end of treatment. The best pregnancy rate (37%) was obtained after a single cervical TAI with fresh semen at 42 h.  相似文献   

4.
Crossbred cows (n = 1073) from five locations had oestrous cycles synchronized with 100 μg of GnRH IM and insertion of controlled internal drug release device (CIDR) on Day 0 followed by 25 mg of PGF2α IM and CIDR removal on Day 7. Kamar® patches were placed on all cows at CIDR removal. Cows were observed three times daily for oestrus after PGF2α administration. In the Ovsynch‐CIDR group, cows detected in oestrus (n = 193) within 48 h after PGF2α were inseminated using the AM–PM rule. Among these cows, 80 received and 113 did not receive a second GnRH at 48 h after PGF2α. Cows (n = 345) not detected in oestrus received a second GnRH at 48 h after PGF2α on Day 9, and fixed‐time AI 16 h after the GnRH on Day 10. In the CO‐Synch‐CIDR group, cows detected in oestrus (n = 224) within 48 h after PGF2α were inseminated using the AM–PM rule. Among these cows, 79 received and 145 did not receive a second GnRH at 64 h after PGF2α. Cows (n = 311) not detected in oestrus received a second GnRH on Day 10 at the time of AI, 64 h after PGF2α. The AI pregnancy rates were not different between the Ovsynch‐CIDR and CO‐Synch‐CIDR groups (p = 0.48). There were no differences in the AI pregnancy rates for cows inseminated at a fixed time (p = 0.26) or at detected oestrus (p = 0.79) between the treatment groups. Among cows inseminated in oestrus, there were no differences in the AI pregnancy rates between cows that received or did not receive the second GnRH (p = 0.47). In conclusion, acceptable AI pregnancy rates can be achieved with or without inclusion of oestrus detection in the Ovsynch‐CIDR and CO‐Synch‐CIDR protocols. Among cows detected in oestrus, cows that received a second GnRH yielded similar pregnancy rates when compared with cows that did not receive the second GnRH.  相似文献   

5.
Two experiments were designed to investigate the administration of intravaginal progesterone in protocols for oestrus and ovulation synchronization in beef heifers. In Experiment 1, cyclic Black Angus heifers (n = 20) received an Ovsynch protocol and were randomly assigned to receive (CIDR‐Ovsynch) or not (Ovsynch) a progesterone device between Days 0 and 7. Treatment with a controlled internal drug release (CIDR) device significantly increased the size of the dominant follicle prior to ovulation (12.8 ± 0.4 CIDR‐Ovsynch vs 11.4 ± 0.4 Ovsynch) (p < 0.02). Plasma progesterone concentrations throughout the experiment were affected by the interaction between group and day effects (p < 0.004). In Experiment 2, cyclic Polled Hereford heifers (n = 382) were randomly assigned to one of the six treatment groups (3 × 2 factorial design) to receive a CIDR, a used bovine intravaginal device (DIB), or a medroxiprogesterone acetate (MAP) sponge and GnRH analogues (lecirelin or buserelin). All heifers received oestradiol benzoate plus one of the devices on Day 0 and PGF on Day 7 pm (device withdrawal). Heifers were detected in oestrus 36 h after PGF and inseminated 8–12 h later, while the remainder received GnRH 48 h after PGF and were inseminated on Day 10 (60 h). The number of heifers detected in oestrus on Day 8 and conception rate to AI on Day 9 were higher (p < 0.01) in the used‐DIB than in the CIDR or MAP groups, while the opposite occurred with the pregnancy rate to FTAI on Day 10 (p < 0.01). There was no effect of progesterone source, GnRH analogue or their interaction on overall pregnancy rates (64.9%). Progesterone treatment of heifers during an Ovsynch protocol resulted in a larger pre‐ovulatory follicle in beef heifers. Progesterone content of intravaginal devices in synchronization protocols is important for the timing of AI, as the use of low‐progesterone devices can shorten the interval to oestrus.  相似文献   

6.
This study aimed to evaluate three regimes for oestrus and ovulation synchronization in Farafra ewes in the subtropics. During autumn, 43 ewes were assigned to (i) controlled internal drug releasing (CIDR)‐eCG group, treated with CIDR for 12 days and eCG at insert withdrawal, n = 13; (ii) PGF2α‐PGF2α group, treated with two PGF2α injections at 11 days interval, n = 14; and (iii) GnRH‐PGF2α‐GnRH group, treated with GnRH, followed 5 days later with PGF2α and 24 h later with a second GnRH, n = 16. Oestrus‐mating detection was carried out at 4 h intervals starting on day 0 [the day of CIDR withdrawal (CIDR‐eCG group), the day of second PGF2α treatment (PGF2α‐PGF2α group) and the day of PGF2α treatment (GnRH‐PGF2α‐GnRH group)]. Ovarian dynamics was monitored by ultrasound every 12 h beginning on day 0 and continued for 4 days. Blood samples were obtained daily for progesterone (P4) and oestradiol 17β (E2) estimation starting on day 0 and continued for 4 days. The obtained results showed that, oestrus expression, ovulation and conception were greater (p < 0.05) in CIDR‐eCG and PGF2α‐PGF2α groups than in GnRH‐PGF2α‐GnRH group. All ewes of PGF2α‐PGF2α group presented, on day of second PGF2α injection with mature CL (P4 > 2.0 ng/ml), compared to 42.9% in GnRH‐PGF2α‐GnRH group (p = 0.01). The peak of oestrus occurred 32–52, 48–60 and 28–96 h after the end of treatment in CIDR‐eCG, PGF2α‐PGF2α and GnRH‐PGF2α‐GnRH groups, respectively. Ovulation started 48 h after treatment in all groups and extended for 24, 36 and 48 h for CIDR‐eCG, PGF2α‐PGF2α and GnRH‐PGF2α‐GnRH groups, respectively. Results demonstrated that oestrus and ovulation synchronization could be efficiently achieved in Farafra ewes using either CIDR‐eCG or PGF2α‐PGF2α regimes; however, the GnRH‐PGF2α‐GnRH treatment induced a more spread oestrus and ovulation that may make the protocol inadequate for timed artificial insemination.  相似文献   

7.
The primary objective of this study was to determine whether a single measurement of intravaginal electrical resistance (VER), using the commercially available Ovatec® probe, can discriminate between dioestrus and oestrus in Bos indicus females, which had been treated to synchronize oestrus. Santa Gertrudis heifers (n = 226) received one of three oestrous synchronization treatments: double PGF2α 10 days apart, 8‐day controlled internal drug release (CIDR) treatment or CIDR pre‐synchronization + PGF2α 10 days after CIDR removal. The heifers were inseminated within 12 h following observed oestrus, or, if not observed, at a fixed time approximately 80 h, following the last synchronization treatment. They were palpated per rectum for signs of pregnancy 9 weeks after artificial insemination (AI). Vaginal electrical resistance measurements were taken at the completion of synchronization treatments (presumed dioestrus), immediately prior to AI (oestrus), and then at 3 and 9 weeks post‐AI. Mean VER differed between presumed dioestrus and oestrus (113.7 vs 87.4, p < 0.001). The area under the receiver operating characteristics (ROC) curve was 0.925, indicating that VER was highly discriminatory between dioestrus and oestrus. Vaginal electrical resistance at time of AI was negatively associated with odds of conception when all inseminations were included in the analyses [odds ratio (OR) = 0.97; 95% CI 0.95–1.00; p = 0.018], but not when fixed time AIs were excluded (OR = 1.00; 95% CI 0.97–1.03; p = 0.982). Mean VER readings differed between pregnant and non‐pregnant animals at both 3 weeks (120.5 vs 96.7, p < 0.001) and 9 weeks (124.0 vs 100.3, p < 0.001) post‐AI. However, 3‐ and 9‐week VER measurements were not highly discriminatory between pregnancy and non‐pregnancy (area under ROC curve = 0.791 and 0.736, respectively). Mean VER at time of AI for animals diagnosed in oestrus differed between each of the oestrous synchronization treatments (84.7, 73.6 and 78.9, groups 1–3 respectively, p < 0.001). These findings suggest that measurement of VER may improve accuracy of oestrus diagnoses when selecting cattle for AI following oestrous synchronization programmes involving tropically adapted cattle.  相似文献   

8.
One hundred eighty-nine Corriedale ewes were used during the non-breeding season to study the "ram effect" stimulus after priming with progestogens. Intravaginal sponges containing either medroxyprogesterone acetate (MAP group, n = 49), fluorogestone acetate (FGA group, n = 49), or progesterone devices (CIDR group, n = 46) were inserted on Day-6 (Day 0 = introduction of the rams). Forty-five ewes were untreated and kept as a control group. On Day 0 the sponges were removed and rams provided with marking harnesses for oestrous detection were placed with the ewes. Onset of estrus was monitored until Day 25, and conception was determined by transrectal ultrasonography. Ewes came into heat during 4 periods: Days 0-3, 5-7, 17-20, and 21-23. The overall number of oestrus ewes were 29%, 53%, 35%, and 50% for the control, MAP, FGA, and CIDR groups, respectively (MAP and CIDR > control, p < 0.05). Control ewes presented oestrus only on Days 17-20 and 21-23. Oestrus in the progestogen-primed ewes was concentrated during Days 0-3 and 17-20, and some ewes came into oestrus on Days 5-7. There were no differences between different primings neither in oestrous response nor in conception rate. The conception rate from matings occurring on Days 0-3 was higher than on those occurring on Days 17-20. We conclude that MAP, FGA, and CIDR is equally effective in improving the response to the ram effect, and the pattern of oestrus in primed ewes was different than previously reported.  相似文献   

9.
AIMS: To determine if the frequency distribution of time to oestrus observed after the introduction of rams, and additional ewes in oestrus, is affected by the administration of oestradiol- 17beta. To determine if the fertility following mating at the first induced oestrus in progesterone-primed ewes may be increased with administration of oestradiol-17beta. METHODS: In Experiment 1, ewes received 40 mug oestradiol- 17beta 3 (E3; n=61) or 5 (E5; n=56) days before the introduction of rams; 61 ewes were controls (C1). In Experiment 2, a controlled internal drug-releasing (CIDR) device was inserted in 95 ewes on Day -5 (Day 0 = introduction of rams). In addition, 47 ewes received oestradiol-17beta on Day 0 (CE), and the remaining 48 were controls (C2). In both experiments, additional ewes, brought into oestrus between Days 0 and 2 by hormonal treatments, were introduced with the rams. Onset of oestrus was estimated by visual observation of ewes marked by rams. Pregnancy status of ewes in Experiment 2 was determined using ultrasound, 30 days after oestrus. RESULTS: The total number of ewes detected in oestrus in Experiment 1 was similar between the three groups. The frequency distribution of ewes in oestrus in the E5 group differed from that of ewes in both C1 (p=0.05) and E3 (p<0.001). A similar number of ewes were detected in oestrus between Days 16-20, but the proportion of ewes in oestrus between Days 21-26 was greater for ewes in C1 than E5 or E3. Mean interval to the onset of oestrus was shorter in C1 than E3 which was shorter than E5 ewes (p<0.001). In Experiment 2, the total number of ewes in oestrus were similar between groups. Ewes in oestrus between Days 1-4 (65% and 64% for C2 and CE, respectively) and conception rates over the same period (81% and 80% for C2 and CE, respectively) were also similar between groups. CONCLUSIONS: Administration of oestradiol-17beta to anoestrous ewes altered the pattern of onset of oestrus, but it did not affect submission or conception rates, regardless of whether or not a short period of progesterone priming with a new CIDR device was included prior to the introduction of rams.  相似文献   

10.
We determined whether a fixed-time AI (TAI) protocol could yield pregnancy rates similar to a protocol requiring detection of estrus, or estrous detection plus TAI, and whether adding a controlled internal device release (CIDR) to GnRH-based protocols would enhance fertility. Estrus was synchronized in 2,598 suckled beef cows at 14 locations, and AI was preceded by 1 of 5 treatments: 1) a CIDR for 7 d with 25 mg of PG F(2alpha) (PGF) at CIDR removal, followed by detection of estrus and AI during the 84 h after PGF; cows not detected in estrus by 84 h received 100 mug of GnRH and TAI at 84 h (control; n = 506); 2) GnRH administration, followed in 7 d with PGF, followed in 60 h by a second injection of GnRH and TAI (CO-Synch; n = 548); 3) CO-Synch plus a CIDR during the 7 d between the first injection of GnRH and PGF (CO-Synch + CIDR; n = 539); 4) GnRH administration, followed in 7 d with PGF, followed by detection of estrus and AI during the 84 h after PGF; cows not detected in estrus by 84 h received GnRH and TAI at 84 h (Select Synch & TAI; n = 507); and 5) Select Synch & TAI plus a CIDR during the 7 d between the first injection of GnRH and PGF (Select Synch + CIDR & TAI; n = 498). Blood samples were collected (d -17 and -7, relative to PGF) to determine estrous cycle status. For the control, Select Synch & TAI, and Select Synch + CIDR & TAI treatments, a minimum of twice daily observations for estrus began on d 0 and continued for at least 72 h. Inseminations were performed using the AM/PM rule. Pregnancy was diagnosed by transrectal ultrasonography. Percentage of cows cycling at the initiation of treatments was 66%. Pregnancy rates (proportion of cows pregnant to AI of all cows synchronized during the synchronization period) among locations across treatments ranged from 37% to 67%. Pregnancy rates were greater (P < 0.05) for the Select Synch + CIDR & TAI (58%), CO-Synch + CIDR (54%), Select Synch & TAI (53%), or control (53%) treatments than the CO-Synch (44%) treatment. Among the 3 protocols in which estrus was detected, conception rates (proportion of cows that became pregnant to AI of those exhibiting estrus during the synchronization period) were greater (P < 0.05) for Select Synch & TAI (70%; 217 of 309) and Select Synch + CIDR & TAI (67%; 230 of 345) cows than for control cows (61%; 197 of 325). We conclude that the CO-Synch + CIDR protocol yielded similar pregnancy rates to estrous detection protocols and is a reliable TAI protocol that eliminates detection of estrus when inseminating beef cows.  相似文献   

11.
This study aimed at comparing the effect of ram semen preserved at 5°C on two milk‐based extenders (UHT skim milk or INRA‐96®, 5% egg yolk) supplemented with 2% glycerol, and the preservation time (24 and 48 h) on conception rates after cervical AI of ewes. In two field trials, 1198 Merino ewes were cervical AI in spontaneous oestrus. In Experiment 1, pooled semen (6 rams) was extended in UHT‐base (fresh, control) or chilled for 24 h in UHT5Y (UHT‐base 5% egg yolk), INRA5Y (INRA‐96® 5% egg yolk), UHT5Y2G (UHT5Y 2% glycerol) or INRA5Y2G (INRA5Y 2% glycerol). In Experiment 2, AI was performed with pooled semen (7 rams) used fresh (extended in UHT‐base or UHT5Y2G, control groups) or chilled (extended in UHT5Y2G) for 24 or 48 h. Conception rate was determined by ultrasound 40 days after AI. INRA‐96®– had similar conception as UHT‐preserved semen (56.7 vs 55.4%, p > 0.05). Addition of 2% glycerol did not modify the results (56.8 vs 55.2%, p > 0.05). Fresh semen extended in UHT‐base, and UHT5Y2G yielded similar conception rates (60 vs 64%, p > 0.05). Preservation for 24 or 48 h in UHT5Y2G gave similar results (49 vs 47%; p > 0.05). In conclusion, ram semen chilled for 24 h in UHT‐ or INRA‐96®‐based extenders yielded similar results, and glycerol addition did not have a detrimental effect. UHT5Y2G might be used to extend ram semen for fresh AI, or to preserve it for 24 or 48 h with acceptable results.  相似文献   

12.
Most fixed-time insemination protocols utilize an injection of GnRH at the beginning of the protocol to initiate a new follicular wave. However, the ability of GnRH to initiate a new follicular wave is dependent on the stage of the estrous cycle. We hypothesized that administering PGF(2α) 3 d before initiating a fixed-time AI protocol would improve synchrony of follicular waves and result in greater pregnancy success. Therefore, our objective was to determine whether inducing luteal regression 3 d before a fixed-time AI protocol would improve control of follicular turnover and pregnancy success to fixed-time AI. Multiparous crossbred cows at 3 locations (n = 108, 296, and 97) were randomly assigned to 1 of 2 treatments: 1) PGF(2α) [25 mg; intramuscularly (i.m.)] on d -9, GnRH (100 μg; i.m.) and insertion of a controlled internal drug-releasing device (CIDR) on d -6, PGF(2α) (25 mg; i.m.) and CIDR removal with PGF(2α) (25 mg; i.m.) at CIDR removal on d 0 (PG-CIDR) or 2) GnRH (100 μg; i.m.) and insertion of a CIDR on d -5 and CIDR removal with PGF(2α) (25 mg; i.m.) at CIDR removal and 4 to 6 h after CIDR removal (5-d CIDR). Cows were time-inseminated between 66 and 72 h (PG-CIDR) or 70 to 74 h (5-d CIDR) after CIDR removal, and GnRH was administered at the time of fixed-time AI. At location 1, ovulatory response to the first injection of GnRH was determined by ultrasonography at the time of GnRH and 48 h after GnRH administration. Among cows with follicles ≥10 mm in diameter, more (P = 0.03) PG-CIDR-treated cows ovulated after the initial GnRH injection (88%, 43/49) compared with the 5-d CIDR-treated cows (68%, 34/50). Pregnancy outcome was not influenced by location (P = 0.96), age of the animal (P = 1.0), cycling status (P = 0.99), BCS (P = 1.0), or any 2-way interactions (P ≥ 0.13). However, pregnancy success was influenced by synchronization protocol (P = 0.04). Pregnancy outcome was greater (P = 0.04) for the PG-CIDR protocol (64%) compared with the 5-d CIDR protocol (55%). In summary, control of follicular turnover was improved by inducing luteal regression 3 d before initiation of a fixed-time AI protocol, and pregnancy success was improved with the PG-CIDR protocol compared with the 5-d protocol.  相似文献   

13.
The objective of the present study was to determine whether oestrous detection with the help of oestrous detection aids during the Heatsynch without timed AI protocol is equally effective with the progesterone‐combined protocol in dairy heifers. A total of 148 heifers were randomly assigned to one of the two groups. A group of heifers treated with Heatsynch with heat detection aids (n = 72) received GnRH on day 0, prostaglandin F2α (PGF2α) on day 7 and oestradiol benzoate (EB) on day 8, while in controlled internal drug release (CIDR)‐Heatsynch group (n = 76), CIDR was included during a period from GnRH to PGF2α. Heifers were checked for oestrus twice daily, i.e. from 09:00 to 10:00 hours and from 15:00 to 16:00 hours starting on day 2 for Heatsynch group and on day 8 in CIDR‐Heatsynch group, and continued up to day 12. KAMAR®heat mount detector (KAMAR® Inc., Steamboat Springs, CO, USA) and ALL‐WEATHER® PAINTSTIK® (LA‐CO Industries Inc., Elk Grove Village, IL, USA) were used as heat detection aids. AI was conducted within 1 h after confirming oestrus in 72 heifers, while 19 animals were transferred with embryo 7 days after oestrus according to the request of the owners. Premature oestrus before PGF2α injection occurred in 18% of Heatsynch group. Of 13 heifers which showed premature oestrus, six were inseminated and two of them conceived. Oestrus detection rate within 12 days after initiation of the protocols did not differ between the two groups (94% vs 95%). There was no difference in the conception rate after first AI (including heifers that were inseminated before PGF2α injection) and embryo transfer between Heatsynch with heat detection aids and CIDR‐Heatsynch groups (36% vs 44% and 70% vs 56%). It is concluded that the use of heat detection aids to monitor the occurrence of premature oestrus prior to PGF2α injection in Heatsynch protocol in dairy heifers was equally effective to the inclusion of CIDR.  相似文献   

14.
The objective of this study was to compare oestrus expression and fertility rate in used and new controlled internal drug releasing (CIDR) device treated anoestrous buffaloes. Furthermore, to determine the timing of ovulation, and fertility rate in estradiol benzoate (EB) and GnRH-administered CIDR-treated anoestrous Nili-Ravi buffaloes. In experiment 1, buffaloes received either a used CIDR (UCIDR, n = 35) or a new CIDR (NCIDR, n = 36) for 7 day and PGF2α on day 6. Oestrous expression was similar (p > 0.05) between UCIDR (88.5%) and NCIDR (96.6%) buffaloes. The pregnancy rate did not differ (p > 0.05) because of treatment (37.1% in UCIDR vs 36.6% in NCIDR). In experiment 2, buffaloes (n = 55) received CIDR device for 7 days and PGF2α, on day 6 and randomly assigned into three treatment groups: (i) CIDR-EB (n = 17) received EB on day 8, (ii) CIDR-GnRH (n = 18) received GnRH on day 9 and (iii) control (n = 20) received no further treatment. Mean interval from CIDR removal to ovulation in CIDR-EB, CIDR-GnRH and CIDR group were 61.3 ± 0.8, 64.9 ± 1.8 and 65.1 ± 16.7 h, respectively. However, the buffaloes in the CIDR-EB and CIDR-GnRH group had lesser variability in the timing of ovulation compared to control. The pregnancy rate of both CIDR-EB group (58%) and CIDR-GnRH group (61%) were tended to be higher (p < 0.1) than control (30%). In conclusion, compared to NCIDR devices, previously UCIDR devices are equally effective to induce oestrus in anoestrous buffaloes resulting optimal pregnancy rate. Administration of EB and GnRH after CIDR removal results in tighter synchrony (less variability) and improved fertility in anoestrous buffaloes. CIDR based synchronization regimens have great potential in fertility improvement in anoestrous buffaloes.  相似文献   

15.
The study investigated, for cycling sheep, synchronizing protocols simultaneously to the standard “P” protocol using progestogens priming with intravaginal devices and gonadotropin. In November 2014, 90 adult Menz ewes were assigned to either the “P” protocol, “PGF” treatment where oestrus and ovulation were synchronized using two injections of prostaglandin 11 days apart or a “GnRH” treatment where the ewes had their oestrus and ovulation synchronized with GnRH (day 0)–prostaglandin (day 6)–GnRH (day 9) sequence. The ewes were naturally mated at the induced oestrus and the following 36 days. Plasma progesterone revealed that 92% of the ewes were ovulating before synchronization and all, except one, ovulated in response to the applied treatments. All “P” ewes exhibited oestrus during the 96‐hr period after the end of the treatments in comparison with only 79.3% and 73.3% for “PGF” and “GnRH” ewes, respectively (p < .05). Onset and duration of oestrus were affected by the hormonal treatment (p < .05); “GnRH” ewes showed oestrus earliest and had the shortest oestrous duration. Lambing rate from mating at the induced oestrus was lower for “P” than for “PGF” ewes (55.6% and 79.3%, respectively; p < .05). The same trait was also lower for “P” than for “PGF” and “GnRH” ewes (70.4%, 89.7% and 86.7%, respectively; p < .05) following the 36‐day mating period. Prostaglandin and GnRH analogue‐based protocols are promising alternatives for both controlled natural mating and fixed insemination of Menz sheep after the rainy season when most animals are spontaneously cycling.  相似文献   

16.
The objectives of this study were to 1) compare cumulative pregnancy rates in a traditional management (TM) scheme with those using a synchronization of ovulation protocol (CO-Synch + CIDR) for timed AI (TAI) in Bos indicus-influenced cattle; 2) evaluate ovarian and hormonal events associated with CO-Synch + CIDR and CO-Synch without CIDR; and 3) determine estrual and ovulatory distributions in cattle synchronized with Select-Synch + CIDR. The CO-Synch + CIDR regimen included insertion of a controlled internal drug-releasing device (CIDR) and an injection of GnRH (GnRH-1) on d 0, removal of the CIDR and injection of PGF2alpha (PGF) on d 7, and injection of GnRH (GnRH-2) and TAI 48 h later. For Exp. 1, predominantly Brahman x Hereford (F1) and Brangus females (n = 335) were stratified by BCS, parity, and day postpartum (parous females) before random assignment to CO-Synch + CIDR or TM. To maximize the number of observations related to TAI conception rate (n = 266), an additional 96 females in which TM controls were not available for comparison also received CO-Synch + CIDR. Conception rates to TAI averaged 39 +/- 3% and were not affected by location, year, parity, AI sire, or AI technician. Cumulative pregnancy rates were greater (P < 0.05) at 30 and 60 d of the breeding season in CO-Synch + CIDR (74.1 and 95.9%) compared with TM (61.8 and 89.7%). In Exp. 2, postpartum Brahman x Hereford (F1) cows (n = 100) were stratified as in Exp. 1 and divided into 4 replicates of 25. Within each replicate, approximately one-half (12 to 13) received CO-Synch + CIDR, and the other half received CO-Synch only (no CIDR). No differences were observed between treatments, and the data were pooled. Percentages of cows ovulating to GnRH-1, developing a synchronized follicular wave, exhibiting luteal regression to PGF, and ovulating to GnRH-2 were 40 +/- 5, 60 +/- 5, 93 +/- 2, and 72 +/- 4%, respectively. In Exp. 3, primiparous Brahman x Hereford, (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. These results indicate that the relatively low TAI conception rate observed with CO-Synch + CIDR in these studies was attributable primarily to failure of 40% of the cattle to develop a synchronized follicular wave after GnRH-1 and also to inappropriate timing of TAI/GnRH-2.  相似文献   

17.
This study aimed to evaluate the effectiveness of hormonal treatments on ovarian activity and reproductive performance in Barki and Rahmani ewes during non‐breeding season. Forty‐eight multiparous ewes, 24 Barki and 24 Rahmani ewes were divided into two groups, 12 lactating and 12 dry ewes for each breed. Controlled internal drug release (CIDR) device was inserted in all ewes for 14 days in conjunction with intramuscular 500 IU equine chronic gonadotrophin (eCG) at day of CIDR removal. Data were analysed using PROC MIXED of SAS for repeated measures. Breed, physiological status and days were used as fixed effects and individual ewes as random effects. Barki ewes recorded higher (p < .05) total number of follicles, number of large follicles, serum estradiol concentration and estradiol: progesterone (E2:P4) ratio compared to Rahmani ewes. Lactating ewes recorded higher (p < .05) number of small follicles and lower concentration of total antioxidant capacity (TAC) compared to dry ewes. Number and diameter of large follicles recorded the highest (p < .05) values accompanied with disappearance of corpora lutea at day of mating. Serum progesterone concentration recorded lower (p < .05) value at day of mating and the highest (p < .05) value at day 35 after mating. CIDR‐eCG protocol induced 100% oestrous behaviour in both breeds, but Rahmani ewes recorded longer (p < .05) oestrous duration compared to Barki. Conception failure was higher (p < .05) in Barki compared to Rahmani ewes. In conclusion, CIDR‐eCG protocol was more potent in improving ovarian activity in Barki compared to Rahmani ewes, but this protocol seems to induce hormonal imbalance in Barki ewes that resulted in increasing conception failure compared to Rahmani ewes.  相似文献   

18.
Synchronization of estrus and ovulation is essential for AI of ewes during a predetermined time frame, and progestogen-eCG treatments are typically used to prepare the ewes. However, eCG is not readily available in the United States, but P.G. 600 (400 IU of eCG and 200 IU of hCG) is available. Thus, we conducted a study to determine the effects of eCG and P.G. 600 on the timing of estrus and ovulation after progestogen withdrawal. Ewes were assigned to two replicates of an experiment with the following treatments: 1) 3-mg norgestomet implant (i.e., one-half of a Syncro-Mate-B [SMB] implant) for 10 d, plus 2 mL of saline i.m. at SMB removal (n = 11); 2) 3-mg SMB implant for 10 d, plus 400 IU of eCG i.m. at SMB removal (n = 13); and 3) 3-mg SMB implant for 10 d, plus P.G. 600 i.m. at implant removal (n = 9). On d 6 after SMB insertion, PGF2alpha was used to induce luteolysis. Beginning 12 h after implant removal, vasectomized rams were used at 12-h intervals to check for estrus. When a ewe was detected in estrus, each ovary was evaluated ultrasonically. Ovaries were evaluated again 16 h later and then at 8-h intervals until ovulation. Treatment altered the interval from implant removal to estrus (less [P < 0.05] in SMB + eCG than in the other two groups) and to ovulation (greatest [P < 0.05] in SMB). However, the treatment x replicate interaction was significant for the intervals from implant removal to estrus (P < 0.03) and from implant removal to ovulation (P < 0.05). An inconsistent response in the SMB-treated ewes seemed to be primarily responsible for the interaction. The intervals to estrus and to ovulation for the SMB-treated ewes were shorter (P < 0.05) in Replicate 1 than in Replicate 2. Also, both intervals seemed to be less consistent between replicates for the SMB + P.G. 600- than for the SMB + eCG-treated ewes; that is, eCG seemed to increase the predictability of the intervals to estrus and to ovulation. Neither the main effects of treatment and replicate nor their interaction were significant for the interval from estrus to ovulation (38.4 /- 3.3 h), size of the ovulatory follicle (7.7 +/- 0.8 mm), or ovulation rate (1.6 +/- 0.2). We concluded from this experiment that eCG is a better choice than P.G. 600 as the gonadotropin to use at the time of progestogen withdrawal to prepare ewes for AI during a predetermined interval.  相似文献   

19.
Application of AI in extensive beef cattle production would be facilitated by protocols that effectively synchronize ovarian follicular development and ovulation to enable fixed-time AI (TAI). The objectives were to determine whether use of a controlled internal drug release (CIDR) device to administer progesterone in a GnRH-based estrous synchronization protocol would optimize blood progesterone concentrations, improve synchronization of follicular development and estrus, and increase pregnancy rates to TAI in beef cows. Beef cows (n = 1,240) in 6 locations within the US Meat Animal Research Center received 1 of 2 treatments: 1)?an injection of GnRH [100 μg intramuscularly (i.m.)] followed by PGF(2α) (PGF; 25 mg i.m.) 7 d later (CO-Synch), or 2) CO-Synch plus a CIDR during the 7 d between GnRH and PGF injections (CO-Synch + CIDR). Cows received TAI and GnRH (100 μg i.m.) at 60 h after PGF. Progesterone was measured by RIA in blood samples collected 2 wk before and at initiation of treatment (d 0) and at PGF injection (d 7). Estrous behavior was monitored by Estrotect Heat Detectors. Pregnancy was diagnosed by ultrasonography 72 to 77 d after TAI. Plasma progesterone concentrations did not differ (P > 0.10) between synchronization protocols at first GnRH injection (d 0), but progesterone was greater (P < 0.01) at PGF injection (d 7) in cows receiving CO-Synch + CIDR vs. CO-Synch as a result of fewer CIDR-treated cows having progesterone ≤1 ng/mL at PGF (10.7 vs. 29.6%, respectively). A greater (P < 0.01) proportion of CO-Synch + CIDR vs. CO-Synch cows were detected in estrus within 60 h after PGF (66.7 vs. 57.8 ± 2.6%, respectively) and a greater (P < 0.01) proportion were pregnant to TAI (54.6 vs. 44.3 ± 2.6%, respectively). For both synchronization protocols, cows expressing estrus within 60 h before TAI had a greater pregnancy rate than cows without estrus. For cows with plasma progesterone ≤1 ng/mL at PGF injection, CO-Synch + CIDR increased pregnancy rate (65.2 ± 5.9 vs. 30.8 ± 3.4% with vs. without CIDR), whereas pregnancy rates did not differ (P > 0.10) between protocols (52.1 ± 2.1 vs. 50.0 ± 2.4%, respectively) when progesterone was >1 ng/mL (treatment × progesterone; P < 0.01). Inclusion of a CIDR in the synchronization protocol increased plasma progesterone concentration, proportion of cows detected in estrus, and pregnancy rate; however, the increase in pregnancy rate from inclusion of the CIDR was primarily in cows with decreasing or low endogenous progesterone secretion during treatment.  相似文献   

20.
At the initiation of most controlled internal drug-releasing (CIDR) device protocols, GnRH has been used to induce ovulation and reset follicular waves; however, its ability to initiate a new follicular wave is variable and dependent on stage of the estrous cycle. The objectives of the current studies were to determine 1) if inducing luteal regression before the injection of GnRH at time of insertion of a CIDR resulted in increased control of follicular development, and 2) if removing endogenous progesterone by inducing luteal regression before insertion of the CIDR decreased variation in LH pulse frequency. In Exp. 1 and 2, Angus-cross cycling beef heifers (n = 22 and 38, respectively) were allotted to 1 of 2 treatments: 1) heifers received an injection of PGF(2α) on d -3, an injection of GnRH and insertion of a CIDR on d 0, and a PGF(2α) injection and CIDR removal on d 6 (PG-CIDR) or 2) an injection of GnRH and insertion of a CIDR on d 0 and on d 7 an injection of PGF(2α) and removal of CIDR (Select Synch + CIDR). In Exp. 3, Angus-cross beef heifers (n = 15) were assigned to 1 of 3 treatments: 1) PG-CIDR; 2) PGF(2α) on d -3, GnRH on d 0, and PGF(2α) on d 6 (PG-No CIDR); or 3) Select Synch + CIDR. Follicular development and ovulatory response were determined by transrectal ultrasonography. Across all experiments, more (P = 0.02) heifers treated with PG before GnRH initiated a new follicular wave after the injection of GnRH compared with Select Synch + CIDR-treated heifers. In Exp. 1, after CIDR removal, interval to estrus did not differ (P = 0.18) between treatments; however, the variance for the interval to estrus was reduced (P < 0.01) in PG-CIDR heifers compared with Select Synch + CIDR heifers. In Exp. 3, there was a tendency (P = 0.09) for LH pulse frequency to be greater among PG-CIDR and PG-No CIDR compared with the Select Synch + CIDR, but area under the curve, mean LH concentrations, and mean amplitude did not differ (P > 0.76). In summary, induction of luteal regression before an injection of GnRH increased the percentage of heifers initiating a new follicular wave. Removal of endogenous progesterone tended to increase LH pulse frequency, and the modified treatment increased the synchrony of estrus after CIDR removal.  相似文献   

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