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1.
Ovarian follicular dynamics and estrous synchronization after Gonadotropin-releasing hormone (GnRH) treatment at Controlled Internal Drug Releasing device (CIDR) insertion were investigated in Japanese Black cows. CIDR was inserted for eight cows at 7 days after estrus. Cows were allocated to either Group A: 8-day CIDR insertion with GnRH treatment on d 0 (n=4, d 0=CIDR insertion) or Group B: 8-day CIDR insertion (n=4). Both groups were injected with prostaglandin F2alpha (PGF2alpha) on d 7. Ultrasonography and blood sampling were performed twice daily. Intensive sampling was performed every 15 min for 8 hr to determine the pulsatile release of LH on d -1, d 5 and d 10. Three of four cows showed intermediate ovulation within 2 days after GnRH treatment during CIDR insertion in Group A, whereas no ovulation was found in Group B. Three of four cows in Group A and all four cows in Group B ovulated after CIDR removal. Plasma progesterone concentrations from d 3 to d 7 in three intermediate ovulatory cows in Group A (8.4 +/- 1.6 ng/ml) was significantly higher than those in Group B (4.1 +/- 1.2 ng/ml; 4 cows) during CIDR insertion (P<0.01). Interval to estrus and ovulation after CIDR removal was observed at 60.0 +/- 12.0 hr and 76.0 +/- 6.9 hr in three cows in Group A, and 75.0 +/- 15.1 hr and 93.0 +/- 20.5 hr in Group B, respectively. There was a significant increase in LH pulse frequency on d 10 compared on d -1 or d 5 in both groups (P<0.05), in addition those on d 10 in Group A tended to be higher than in Group B. As a result, GnRH treatment at CIDR insertion at 7 days after estrus induced intermediate ovulation with formation of corpus luteum (CL) and rather synchronized emergence of ovulatory follicle during CIDR insertion. These induced CL increased plasma progesterone concentrations and contributed to precise synchronization.  相似文献   

2.
This study compared two types of controlled internal drug release (CIDR)-based timed artificial insemination (TAI) protocol for treatment of repeat breeder dairy cows. In the first trial of the experiment, 55 repeat breeder cows were randomly assigned to the following two treatments. (1) In the EB group, a CIDR device was inserted into the cows, and then the cows were administered an injection of 1 mg estradiol benzoate (EB) plus 50 mg progesterone (P4; Day 0). On Day 7, they were given an injection of PGF(2alpha) and the CIDR device was removed. The cows were given an injection of 1 mg EB on Day 8 and were subjected to TAI 30 h later (n=27). (2) In the gonadotrophin releasing hormone (GnRH) group, a CIDR device was inserted into the cows, and then the cows were administered an injection of 250 microg gonadorelin (GnRH; Day 0). On Day 7, they were given an injection of PGF(2alpha) and the CIDR device was removed. The cows were given an injection of 250 microg GnRH on Day 9 and were subjected to TAI 17 h later (n=28). In the second trial, 41 repeat breeder cows that were confirmed as not pregnant in the first trial were randomly assigned to the same two treatments used in the first trial (an EB group of 20 cows and a GnRH group of 21 cows). The ovaries of 15 cows from each group were examined by transrectal ultrasonography in order to observe the changes in ovarian structures, and blood samples were collected for analysis of serum P4 concentrations. The pregnancy rates following TAI in the first (18.5 vs. 32.1%) and second (40.0 vs. 38.1%) trials and the combined rates (27.7 vs. 34.7%) did not differ between the EB and GnRH groups. The proportions of cows with follicular wave emergence within 7 days did not differ between the EB (12/15) and GnRH groups (13/15). The interval to wave emergence was shorter (P<0.01) in the GnRH group than in the EB group, but there was no difference in the mean diameters of dominant follicles on Day 7 between the groups. Moreover, the proportions of cows with synchronized ovulation following a second EB or GnRH treatment did not differ between the groups. In conclusion, treatment with either EB or GnRH in a CIDR-based TAI protocol results in synchronous follicular wave emergence, follicular development, synchronous ovulation, and similar pregnancy rates for TAI in repeat breeder cows.  相似文献   

3.
We studied the effects of administering estradiol benzoate (EB) plus progesterone (P4) as part of a CIDR-based protocol during the growth or static phases of dominant follicle development on follicular wave emergence, follicular growth, synchrony of ovulation and pregnancy rate following CIDR withdrawal, treatment with PGF(2alpha) and GnRH, and fixed-time artificial insemination (TAI). Forty-one previously synchronized lactating Holstein dairy cows were randomly allocated to three treatment groups. The control group (n=14) received a CIDR on the third day after ovulation only (Day 0). The two treatment groups were administered CIDRs comprising 2 mg EB and 50 mg P4 either on the third (T1, n=14) or eighth day (T2, n=13) after ovulation (Day 0). All cows received PGF(2alpha) after CIDR removal on Day 7, GnRH on Day 9, and TAI 16 h after GnRH treatment. The proportion of cows with follicular wave emergence within 8 days of treatment differed (P<0.01) among the control (14.3%), T1 (85.7%), and T2 groups (92.9%). However, the mean intervals between treatment and wave emergence were not significantly different. There were significant differences in the diameters of the dominant follicles on Day 7 (P<0.01) and in preovulatory follicles on Day 9 (P<0.01), with the largest follicles observed in the control group and the smallest follicles observed in the T2 group. In contrast, the numbers of cows showing synchronous ovulation after GnRH treatment (92.9 to 100.0%) and pregnancy following TAI (46.2 to 50.0%) were similar between the treatment groups. The results showed that, irrespective of the phase (growth or static) of the dominant follicle, administration of 2 mg EB plus 50 mg P4 to CIDR-treated lactating dairy cows induced consistent follicular wave emergence and development, synchronous ovulation after GnRH administration, and similar pregnancy rates following TAI.  相似文献   

4.
The objectives of this study were to determine the effects of incorporating a progesterone intravaginal insert (CIDR) between the day of GnRH and PGF2alpha treatments of a timed AI protocol using estradiol cypionate (ECP) to synchronize ovulation on display of estrus, ovulation rate, pregnancy rate, and late embryonic loss in lactating cows. Holstein cows, 227 from Site 1 and 458 from Site 2, were presynchronized with two injections of PGF2alpha on study d 0 and 14, and subjected to a timed AI protocol (100 mixrog of GnRH on study d 28, 25 mg of PGF2alpha on study d 35, 1 mg of ECP on study d 36, and timed AI on study d 38) with or without a CIDR insert. Blood was collected on study d 14 and 28 for progesterone measurements to determine cyclicity. Ovaries were scanned on d 35, 37, and 42, and pregnancy diagnosed on d 65 and 79, which corresponded to 27 and 41 d after AI. Cows receiving a CIDR had similar rates of detected estrus (77.2 vs. 73.8%), ovulation (85.6 vs. 86.6%), and pregnancy at 27 (35.8 vs. 38.8%) and 41 d (29.3 vs. 32.3%) after AI, and late embryonic loss between 27 and 41 d after AI (18.3 vs. 16.8%) compared with control cows. The CIDR eliminated cows in estrus before the last PGF2alpha injection and decreased (P < 0.001) the proportion of cows bearing a corpus luteum (CL) at the last PGF2alpha injection because of less ovulation in response to the GnRH and greater spontaneous CL regression. Cyclic cows had greater (P = 0.03) pregnancy rates than anovulatory cows at 41 d after AI (33.8 vs. 20.4%) because of decreased (P = 0.06) late embryonic loss (16.0 vs. 30.3%). The ovulatory follicle was larger (P < 0.001) in cows in estrus, and a greater proportion of cows with follicles > or = 15 mm displayed estrus (P < 0.001) and ovulated (P = 0.05) compared with cows with follicles <15 mm. Pregnancy rates were greater (P < 0.001) for cows displaying estrus, which were related to the greater (P < 0.001) ovulation rate and decreased (P = 0.08) late embryonic loss for cows in estrus at AI. Cows that were cyclic and responded to the presynchronization protocol (high progesterone at GnRH and CL at PGF2alpha) had the highest pregnancy rates. Incorporation of a CIDR insert into a presynchronized timed AI protocol using ECP to induce estrus and ovulation did not improve pregnancy rates in lactating dairy cows. Improvements in pregnancy rates in cows treated with ECP to induce ovulation in a timed AI protocol are expected when more cows display estrus, thereby increasing ovulation rate.  相似文献   

5.
We compared synchronization and pregnancy rates, and the increase in blood progesterone concentrations during luteal development, between (1) Ovsynch plus an intravaginal controlled internal drug release (CIDR) device protocol followed by timed embryo transfer (timed ET), and (2) a conventional estrus synchronization method using PGF(2 alpha) and ET in suckled postpartum Japanese Black beef cows. Cows in the PGF group (n=18) received a PGF(2 alpha) analogue when a CL was first palpated per rectum at 10-d intervals after 1 to 2 month postpartum. Cows (n=11), which showed estrus (Day 0) within 5 d of the PGF(2 alpha), and had a CL on Day 7, received ET. Cows in the Ovsynch+CIDR group (n=19) underwent the Ovsynch protocol plus a CIDR for 7 d (GnRH analogue and CIDR on Day-9, PGF(2alpha) analogue with CIDR removal on Day-2, and GnRH analogue on Day 0), with ET on Day 7. The ovulation synchronization (100%) and embryo transfer (100%) rates in the Ovsynch+CIDR group were greater (P<0.01) than the estrus synchronization (66.7%) and the embryo transfer (61.1%) rates in the PGF group. The postpartum interval at ET in the Ovsynch+CIDR group (62.5 +/- 2.5 d) was shorter (P<0.01) than in the PGF group (74.9 +/- 3.9 d). The pregnancy rate in the Ovsynch+CIDR group (57.9%) did not differ significantly from that in the PGF group (50.0%). Plasma progesterone concentrations were not significantly different in the two groups on Days 0, 1, 2, 5, 7, 14 and 21. In summary, higher synchronization and transfer rates, and shorter postpartum interval to ET, can be achieved with timed ET following the Ovsynch plus CIDR protocol than after estrus with the single PGF(2 alpha) treatment followed by ET in suckled postpartum recipient beef cows. Pregnancy rates were similar. Also, the increase in blood progesterone concentrations during luteal development following ovulation synchronized by the Ovsynch plus CIDR protocol was similar to that after estrus induced by the PGF(2 alpha) treatment.  相似文献   

6.
The objectives of this observational study were to document ovarian and endocrine responses associated with the treatment of cystic ovarian follicles (COFs) in dairy cows, using gonadotropin releasing hormone (GnRH) and prostaglandin F2alpha (PGF) with or without exogenous progesterone. A secondary objective was to determine pregnancy establishment following synchronization of ovulation and timed insemination in cows diagnosed with COFs. In trial I, 18 Holstein cows diagnosed with COFs received 2 injections of 100 microg GnRH, 9 d apart, with 25 mg PGF given 7 d after the 1st GnRH. A new follicle developed in all 18 cows after the 1st GnRH, and 83% of cows ovulated following the 2nd GnRH. Cows were inseminated 16 h after the 2nd GnRH. Of the 17 cows available for pregnancy diagnosis, 7 were confirmed pregnant. In trial II, 8 cows with COFs received GnRH and an intravaginal progesterone device (CIDR) concurrently, then PGF 7 d later. The CIDR was removed 2 d after PGF administration. Plasma estradiol concentrations declined following CIDR insertion. In all cows, a new follicle developed following GnRH treatment; estradiol-surge and estrus occurred spontaneously after CIDR-removal. Seven of 8 cows ovulated the new follicle. In dairy cows diagnosed with COFs, treatment with GnRH followed by PGF 7 d later, with or without exogenous progesterone, resulted in the recruitment of a healthy new follicle; synchronization of ovulation and timed insemination resulted in a 41% pregnancy rate.  相似文献   

7.
Two experiments were conducted to evaluate whether hCG administered 7 d before initiating the CO-Synch + controlled internal drug release (CIDR) ovulation synchronization protocol (Exp. 1 and 2), or replacing GnRH with hCG at the time of AI (Exp. 1), would improve fertility to a fixed-time AI (TAI) in suckled beef cows. In addition, the effects of hCG on follicle dynamics, corpus luteum development, and concentrations of progesterone (P4) were evaluated. In Exp. 1, cows were stratified by days postpartum, age, and parity and assigned randomly to a 2 × 2 factorial arrangement of 4 treatments: 1) cows received 100 μg of GnRH at CIDR insertion (d -7) and 25 mg of PGF(2α) at CIDR removal (d 0), followed in 64 to 68 h by a TAI plus a second injection of GnRH at TAI (CG; n = 29); 2) same as CG but the second injection of GnRH at the time of insemination was replaced by hCG (CH; n = 28); 3) same as CG, but cows received hCG 7 d (d -14) before CIDR insertion (HG; n = 28); and 4) same as HG, but cows received hCG 7 d (d -14) before CIDR insertion (HH; n = 29). Pregnancy rates were 52, 41, 59, and 38% for GG, GH, HG, and HH, respectively. Cows receiving hCG (39%) in place of GnRH at TAI tended (P = 0.06) to have poorer pregnancy rates than those receiving GnRH (56%). Pre-CO-Synch hCG treatment increased (P < 0.05) the percentage of cows with concentrations of P4 >1 ng/mL at d -7, increased (P < 0.02) concentration of P4 on d -7, and decreased (P < 0.001) the size of the dominant follicle on d 0 and 3, compared with cows not treated with hCG on d -14. In Exp. 2, cows were stratified based on days postpartum, BCS, breed type, and calf sex and then assigned to the CG (n = 102) or HG (n = 103) treatments. Overall pregnancy rates were 51%, but no differences in pregnancy rates were detected between treatments. Pre-CO-Synch hCG treatment increased (P < 0.05) the percentage of cows cycling on d -7 and increased (P < 0.05) concentrations of P4 on d -7 compared with pre-CO-Synch controls. Therefore, pretreatment induction of ovulation after hCG injection 7 d before initiation of CO-Synch + CIDR protocol failed to enhance pregnancy rates, but replacing GnRH with hCG at the time of AI may reduce pregnancy rates.  相似文献   

8.
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   

9.
We investigated whether CIDR-based ovulation-synchronization protocols inhibit secretion of prostaglandin (PG) F2alpha from the uterus in the following luteal phase in non-cycling beef cows. Ten early (a month) postpartum non-cycling Japanese Black beef cows were treated with (1) Ovsynch (GnRH analogue on Day 0, PGF2alpha analogue on Day 7, and GnRH analogue on Day 9; n=3), (2) Ovsynch+CIDR (Ovsynch protocol plus a CIDR for 7 days from Day 0; n=4), or (3) estradiol benzoate (EB) Ovsynch+CIDR (EB on Day 0 in lieu of the first GnRH treatment followed by the Ovsynch+CIDR protocol; n=3). An oxytocin challenge was administered on Day 24 to examine uterine PGF2alpha secretion. Plasma concentrations of 13,14-dihydro-15-keto- PGF2alpha were lower at 30-120 min after oxytocin administration in the Ovsynch+CIDR group and 75 min after administration in the EB Ovsynch+CIDR group than in the Ovsynch group (P<0.05). Plasma progesterone concentrations were higher from Days 1 to 7 in the Ovsynch+CIDR group and from Days 1 to 5 in the EB Ovsynch+CIDR group than in the Ovsynch group (P<0.05). The progesterone concentrations were higher on Days 27 and 29 in both CIDR-treated groups than in the Ovsynch group (P<0.05). In conclusion, in non-cycling beef cows, CIDR-based ovulation-synchronization protocols inhibit uterine PGF2alpha secretion in the following luteal phase and prevent premature luteolysis as is seen with the Ovsynch protocol.  相似文献   

10.
In Exp. 1, 187 lactating beef cows were treated with injections of GnRH 7 d before and 48 h after prostaglandin F2alpha (PGF2alpha; Cosynch) or with Cosynch plus a 7-d treatment with an intravaginal progesterone (P4)-releasing insert (CIDR-B; Cosynch + CIDR). In Exp. 2, 183 lactating beef cows were treated with the Cosynch protocol or with Cosynch plus a 7-d treatment with norgestomet (Cosynch + NORG). In Exp. 1 and 2, blood samples for later P4 analyses were collected on d -17, -7 (first GnRH injection), 0 (PGF2alpha injection), and at timed artificial insemination (TAI; 48 h after PGF2alpha). In Exp. 3, 609 lactating beef cows were treated with the Cosynch + CIDR protocol or were fed 0.5 mg of melengestrol acetate (MGA) per day for 14 d before initiating the Cosynch protocol 12 d after the 14th d of MGA feeding (MGA + Cosynch). Blood samples were collected as in Exp. 1 and 2, plus additional samples on d -33 and -19 before PGF2alpha. In Exp. 4, 360 lactating beef cows were treated with a Cosynch + CIDR protocol, with TAI occurring at either 48 or 60 h after PGF2alpha, while receiving either GnRH or saline to form four treatments. Blood samples were collected as in Exp. 1 and 2. In Exp. 1, addition of P4 reduced the ability of the first GnRH injection to induce ovulation in anestrous cows with low P4 before PGF2alpha but improved (P = 0.06) pregnancy rates (61 vs 66%). In Exp. 2, the addition of NORG mimicked P4 by likewise increasing (P < 0.01) pregnancy rates (31 vs 51%) beyond those after Cosynch. In Exp. 3, the Cosynch + CIDR protocol increased (P < 0.001) pregnancy rates from 46 to 55% compared to the MGA + Cosynch protocol. In Exp. 4, administration of GnRH at TAI improved (P < 0.05) pregnancy outcomes (50 vs 42%), whereas timing of TAI had limited effects. We conclude that a progestin treatment concurrent with the Cosynch protocol improved pregnancy outcomes in all experiments, but pretreatment of cows with MGA was not as effective as the CIDR insert or NORG implants in this Cosynch-TAI model. Most of the improvement in pregnancy rates was associated with the increase in pregnancy rates of anestrous cows, regardless of whether ovulation was successfully induced in response to GnRH 7 d before PGF2alpha. Injection of GnRH at TAI following the Cosynch + CIDR protocol increased pregnancy rates in cycling cows with high P4 before the PGF2alpha injection and in anestrous cows with low P4 before PGF2alpha injection.  相似文献   

11.
The objective of this experiment was to examine the effects of varying the interval from follicular wave emergence to progestin (controlled internal drug-releasing insert, CIDR) withdrawal on follicular dynamics and the synchrony of estrus. A secondary objective was to assess the effects of causing the dominant follicle (DF) to develop in the presence or absence of a corpus luteum (CL) on follicular dynamics and the synchrony of estrus and ovulation. The experiment was designed as a 2 x 2 x 2 factorial arrangement of treatments with injection of GnRH or estradiol-17 beta and progesterone (E2 + P4) at treatment initiation, duration of CIDR treatment, and injection of PG (prostaglandin F2 alpha) or saline at the time of CIDR insertion as main effects. Estrous cycles (n = 49) in Angus cows were synchronized, and treatments commenced on d 6 to 8 of the estrous cycle. Cows were randomly assigned to receive a CIDR containing 1.9 g of P4 for 7 or 9 d. Approximately half the cows from each CIDR group received either GnRH (100 micrograms) or E2 + P4 (1 mg of E2 + 100 mg of P4) at CIDR insertion. Cows in GnRH or E2 + P4 groups were divided into those that received PG (37.5 mg) or saline at CIDR insertion. All cows received PG (25 mg) 1 d before CIDR removal. Daily ovarian events were monitored via ultrasound. The intervals from GnRH or E2 + P4 treatment to follicular wave emergence were 1.4 and 3.3 d, respectively (P < 0.05). The interval from follicular wave emergence to CIDR removal was longer (P < 0.05) for cows treated with GnRH (6.6 d) than those treated with E2 + P4 (4.7 d) and longer (P < 0.05) for those fitted with a CIDR for 9 d (6.5 d) than those with a CIDR in place for 7 d (4.8 d). Cows treated with PG or GnRH at CIDR insertion had a larger (P < 0.05) DF at CIDR removal than those treated with saline or E2 + P4. Treatment with a CIDR for 9 d also resulted in a larger (P < 0.07) DF at CIDR removal compared with cows fitted with a CIDR for 7 d. The interval from CIDR removal to estrus was shorter (P < 0.05) in cows treated with PG than those treated with saline. The synchrony of estrus and ovulation was not affected by any of the treatments (P > 0.05). Altering the interval from follicular wave emergence to progestin removal or creating different luteal environments in which the DF developed caused differences in the size of the DF at CIDR removal and the timing of the onset of estrus, but it did not affect the synchrony of estrus or ovulation.  相似文献   

12.
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   

13.
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   

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 objective of this study was to determine the effect of exogenous progesterone administration at ovulation and during the early development of the CL, on its future sensitivity to a single administration of PGF2a in mares and cows. Horse Retrospective reproductive data from an equine clinic in the UK during three breeding seasons were used. Mares were divided into: control group, cycles with single ovulations; double ovulation group cycles with asynchronous double ovulations; and PRID group: cycles with single ovulations and treatment with intravaginal progesterone device (CIDR) immediately after the ovulation. All mares were treated with d‐cloprostenol (PGF) at either: (i) 88 hr; (ii) 96 hr; (iii) 104 hr; or (iv) 112 hr after the last ovulation. Cattle A total of nine non‐lactating Holstein cows were used. All cows were administered PGF14 d apart and allocated to one of two groups control group GnRH was administered 56 hr after the second PGF administration. CIDR group CIDR was inserted at the same time of GnRH administration. All cows were administered PGF at 120 hr post‐ovulation. The complete luteolysis rate of mares with double ovulation (66.7%) and those treated with exogenous progesterone (68.4%) was significantly higher than the rate of mares with single ovulation (35.6%) at 104 hr. In the cow, however, the treatment with CIDR did not increase the luteolytic response in cows treated at 120 hr post‐ovulation. In conclusion, the degree of complete luteolysis can be influenced by increasing the concentration of progesterone during the early luteal development in mares.  相似文献   

16.
Reproductive performance of two types of timed artificial insemination (TAI) protocols with or without intravaginal progesterone insert (CIDR) was investigated in a commercial herd of Holstein heifers. A total of seventy-four heifers with 14.4 months of age were allocated to two groups; Ovsynch (n=44) and estradiol benzoate (EB) used Heatsynch (EB-Heatsynch, n=30), and each group was additionally divided into two subgroups with CIDR insertion from day 0 to 7 (n=36) and without CIDR group (n=38). Blood was collected for progesterone (P4) analysis and ovarian finding was monitored with ultrasonography. Heifers in CIDR-treated group resulted in higher pregnancy rate as compared to No-CIDR-treated group (63.9% vs 21.1%, P<0.01). Heifers with functional corpus luteum (CL) on day 0 resulted in significantly higher pregnancy rate in CIDR-treated group than No-CIDR-treated group (day 0: 67.9% vs 13.0%, P<0.01). CIDR insertion suppressed the intermediate ovulation during the first 7 days and the period from the second GnRH or EB administration to TAI as compared to No-CIDR-treated group (first 7 days: 33.3% vs. 52.6%; P<0.05, before TAI: 11.1% vs. 37.0%; P<0.05). In conclusion, the selected TAI protocols with CIDR provided acceptable pregnancy rate and contributed to the economical improvement by shortening the average age of first calving approximately for 2.5 months as compared to the previous management without TAI protocols.  相似文献   

17.
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   

18.
Four experiment stations (IL, KS, MN, and MO) conducted experiments to determine effects of introducing a CIDR (controlled internal device release) into an ovulation control program for postpartum suckled beef cows. Five hundred sixty cows were assigned randomly to two treatments: 1) 100 microg of GnRH (i.m.) followed in 7 d with 25 mg of PGF2alpha, followed in 48 h by a second injection of GnRH and one fixed-time insemination (Cosynch; n = 287) or 2) Cosynch plus one CIDR during the 7 d between the first injection of GnRH and PGF2alpha (Cosynch+P; n = 273). Cows at three stations were inseminated at the time of the second GnRH injection (n = 462), whereas 98 cows at the fourth station were inseminated 16 to 18 h after that injection. Blood samples were collected at d -17, -7, 0, and 2 relative to PGF2alpha to determine concentrations of progesterone. Ultrasonography was used to monitor follicle diameter on d 2 and to determine the presence of an embryo at 30 to 35 d after insemination. Pregnancy rates were greater (P < 0.05) for Cosynch+P- (58%) than for Cosynch-treated (48%) cows. No station x treatment interaction occurred; however, cows at MO (62%) and KS (60%) had greater (P < 0.05) pregnancy rates than those at IL (47%) and MN (44%). Cows that had follicles > 12 mm on d 2 had greater (P < 0.01) pregnancy rates than those with follicles < or = 12 mm regardless of treatment. Pregnancy rates were similar between Cosynch and Cosynch+P treatments when cycling cows had elevated concentrations of progesterone at d 0, but pregnancy rates were greater (P < 0.05) in the Cosynch+P (79%) than in the Cosynch (43%) treatment when cycling cows had low concentrations of progesterone on d 0 (at PGF2alpha injection). Similarly, among noncycling cows, pregnancy rates were greater (P < 0.05) in the Cosynch+P (59%) treatment than in the Cosynch (39%) treatment. Cows in greater body condition at the onset of the breeding season experienced improved (P < 0.001) overall pregnancy rates. Pregnancy rates for cows that calved > 50 d before the onset of the breeding season were greater (P < 0.01) than those for cows that calved < or = 50 d. Thus, treatment of suckled cows with Cosynch yielded acceptable pregnancy rates, but addition of a CIDR improved pregnancy rates in noncycling cows. Body condition and days postpartum at initiation of the breeding season affected overall efficacy of the Cosynch and Cosynch+P protocols.  相似文献   

19.
The effects of estradiol-17beta (E-17beta) or estradiol benzoate (EB) on gonadotrophin release, estrus and ovulation in beef cattle were evaluated in two experiments. In experiment 1, 16 ovariectomized cows received a previously used CIDR insert from days 0 to 7 and 1mg of EB on day 8; they also received 5mg of E-17beta on days 0 or 1, or 5mg of E-17beta+100mg of progesterone on day 0. There was only an effect of time (P<0.0001) on plasma concentrations of progesterone, estradiol, FSH, and LH. Following treatment with E-17beta, plasma FSH concentrations were suppressed for approximately 36 h, whereas plasma LH concentrations were reduced (P<0.05) for 6 h, but surged within 24 h. Injecting 1mg of EB 24 h after CIDR removal decreased (P<0.02) plasma LH concentrations for 6h, followed by an LH surge at 18 h. In experiment 2, ovary-intact heifers (n=40) received a used CIDR and 5mg of E-17beta+100mg of progesterone on day 0. On day 7, CIDR were removed, PGF given, and heifers received nothing (control) or 1mg of EB 12, 24, or 36 h later. In these groups, plasma LH peaked (mean+/-SEM) 78.0+/-23.0, 37.8+/-8.5, 44.4+/-10.3, and 51.0+/-5.1 h after CIDR removal (means, P<0.001; variances, P<0.001) and intervals from CIDR removal to ovulation were 102.0+/-6.7, 63.6+/-3.6, 81.6+/-3.5, and 78.0+/-4.1h (P<0.05). The interval from CIDR removal to ovulation was shorter and less variable in EB-treated groups; the interval from EB to ovulation was shortest (P<0.05) in the 12-h group. In summary, E-17beta or EB decreased both FSH and LH, but LH increased after 6h (despite elevated progesterone concentrations). Following CIDR removal, 1mg of EB effectively synchronized LH release, and ovulation (in intact cattle), but the interval from CIDR removal to EB treatment affected the time of ovulation.  相似文献   

20.
Ovsynch is a program developed to synchronize ovulation for timed breeding. In this paper, the authors investigate whether controlled internal drug release (CIDR)-based protocols prevent premature ovulation before timed-artificial insemination (AI) when Ovsynch is started a few days before luteolysis in cycling beef cows. Nine beef cows at 16 days after oestrus were treated with (1) Ovsynch, i.e. gonadotropin releasing hormone (GnRH) analogue on day 0, prostaglandin (PG) F(2alpha) analogue on day 7 and GnRH analogue on day 9 with timed-AI on day 10, (n=3); (2) Ovsynch+CIDR (Ovsynch protocol plus a CIDR for 7 days from day 0, n=3), or (3) oestradiol benzoate (OB)+CIDR+GnRH (OB on day 0 in lieu of the first GnRH treatment, followed by the Ovsynch+CIDR protocol, n=3). In the Ovsynch group (1) plasma progesterone concentrations fell below 0.5 ng/mL earlier (day 5) than in both CIDR-treated groups (2) and (3), where this occurred on day 8. Plasma oestradiol-17beta concentrations peaked on day 8 in the Ovsynch group and on day 9 in both CIDR-treated groups. The dominant follicle ovulated on day 10 in the Ovsynch group and on day 11 in both CIDR-treated groups. Thus, both CIDR-based protocols prevented premature ovulation before timed-AI in Ovsynch when the protocol was started a few days before luteolysis. This reflects the fact that progesterone levels remained high until the beef cattle were treated with PGF(2alpha).  相似文献   

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