Progesterone-releasing Intravaginal Device Removal Research Articles

Effect of a progesterone-releasing intravaginal device (PRID) for 8 days during a modified Ovsynch protocol on pregnancy outcomes in lactating Holstein cows

Our objective was to evaluate the effect of a progesterone-releasing intravaginal device (PRID) in a 7-d Ovsynch protocol on pregnancy per artificial insemination (P/AI) and pregnancy loss, compared with a standard 7-d Ovsynch protocol without progesterone supplementation. We hypothesized that progesterone supplementation during an Ovsynch protocol would increase P/AI and decrease pregnancy loss. Data were collected on lactating Holstein cows (n = 716) that either received a 7-d Ovsynch protocol (control: d 0, 100 µg of GnRH; d 7, 500 µg of cloprostenol; d 9, µg of GnRH; n = 360) or a modified Ovsynch protocol with addition of a PRID (PRIDsynch; d 0, 100 µg of GnRH + PRID; d 7, 25 mg of dinoprost; d 8, PRID removal; d 9, 100 µg of GnRH; n = 356). All cows received timed artificial insemination (TAI) approximately 16 h after the second GnRH treatment. Pregnancy diagnosis was performed via ultrasonography on d 38 ± 3 after TAI and rechecked on d 80 ± 7 after TAI. Reproductive performance differed between treatments, with PRIDsynch cows having greater (38.9%) P/AI compared with control cows (31.7%) at d 38 ± 3 and also at d 80 ± 7 (34.6% vs. 28.9%, for PRIDsynch and control cows, respectively). Pregnancy loss did not differ among treatments.

PSV-B-15 Comparison of the 7-day Cosynch and 8-day Estradiol-Based Protocols for Synchronization of Ovulation and Timed Artificial Insemination in Suckled Bos Taurus Cows

Abstract The objective was to compare pregnancy rates (PR) on day 30 and pregnancy loss between days 30 and 60 (PL) after timed artificial insemination (TAI; day 0) using 2 synchronization protocols, and plasma progesterone on day 18 in suckled beef cows. Angus cows were randomly assigned to either 7-d progesterone CoSynch (7-d P + GnRH) or 8-d progesterone + estradiol (8-d P + ES) synchronization protocols for TAI. On day -10, cows in the 7-d P + GnRH treatment group (n=574) received a progesterone-releasing intravaginal device (PIVD) and GnRH, on day -3 the PIVD was removed and cows received cloprostenol. On day 0 (64 h after PIVD removal), cows received GnRH and were subjected to TAI. On Day -10, cows in the 8-d P + ES treatment group (n=574) received a PIVD and estradiol benzoate, on Day -2 the PIVD was removed, and cows received cloprostenol and estradiol cypionate. On day 0 (48 h after PIVD removal), cows were subjected to TAI. The TAI pregnancy rates for each treatment were determined on day 30 and day 60. In a subset of cows [n=81, (7-d P + GnRH, n=41; 8-d P + ES, n=40)], serum progesterone concentration was evaluated on day 18. The PR (7-d P + GnRH=48.9%; 8-d P + ES=45.6%) and PL (7-d P + GnRH=3.6%; 8-d P + ES=4.6%) did not differ (P≥0.28) between treatment groups. In a subset of cows, serum progesterone concentration on day 18 did not differ (P=0.67) between treatment groups but tended to be less (P=0.07) in cows that had PL compared with cows that had no PL. In conclusion, there was no difference in PR and PL between suckled beef cows using 7-d CoSynch or 8-d estradiol-based protocols for synchronization of ovulation and TAI.

Comparison of reproductive management programs for submission of Holstein heifers for first insemination with conventional or sexed semen based on expression of estrus, pregnancy outcomes, and cost per pregnancy

Our objective was to evaluate reproductive management programs for submission of Holstein heifers for first insemination with conventional or sexed semen. In experiment 1, nulliparous Holstein heifers (n = 462) were submitted to a 5-d progesterone-releasing intravaginal device (PRID)-Synch protocol [d 0, GnRH + PRID; d 5, PGF2α - PRID; d 6, PGF2α; d 8, GnRH + TAI] and were randomly assigned for PRID removal on d 5 or 6 of the protocol followed by timed artificial insemination (TAI) with conventional semen. Delaying PRID removal decreased early expression of estrus before scheduled TAI (0.9 vs. 12.2%), and pregnancies per AI (P/AI) did not differ between treatments. In experiment 2, nulliparous Holstein heifers (n = 736) from 3 commercial farms were randomized within farm to 1 of 3 treatments for first AI with sexed semen: (1) CIDR5 [d -6, GnRH + controlled internal drug release (CIDR); d -1, PGF2α - CIDR; d 0, PGF2α; d 2, GnRH + TAI]; (2) CIDR6 (d -6, GnRH + CIDR; d -1, PGF2α; d 0, PGF2α - CIDR; d 2, GnRH + TAI); and (3) EDAI (PGF2α on d 0 followed by once-daily estrous detection and AI). Delaying CIDR removal decreased early expression of estrus before scheduled TAI (0.004 vs. 27.8%); however, CIDR5 heifers tended to have more P/AI at 35 (53 vs. 45 vs. 46%) and 64 (52 vs. 45 vs. 45%) days after AI than CIDR6 and EDAI heifers, respectively. Overall, CIDR5 and CIDR6 heifers had fewer days to first AI and pregnancy than EDAI heifers which resulted in less feed costs than EDAI heifers due to fewer days on feed until pregnancy. Despite greater hormonal treatment costs for CIDR5 heifers, costs per pregnancy were $16.66 less for CIDR5 than for EDAI heifers. In conclusion, delaying PRID removal by 24 h within a 5-d PRID-Synch protocol in experiment 1 suppressed early expression of estrus before TAI, and P/AI for heifers inseminated with conventional semen did not differ between treatments. By contrast, although delaying CIDR removal by 24 h within a 5-CIDR-Synch protocol in experiment 2 suppressed early expression of estrus before TAI, delaying CIDR removal by 24 h tended to decrease P/AI for heifers inseminated with sexed semen. Further, submission of heifers to a 5-d CIDR-Synch protocol for first AI tended to increase P/AI and decrease the cost per pregnancy compared with EDAI heifers.

Effect of ovulation synchronization program and season on pregnancy to timed artificial insemination in suckled beef cows

This study was conducted to (i) evaluate the requirement for the administration of GnRH coincident with insertion of a progesterone-releasing intravaginal device (PRID) and (ii) the effect of supplementing with 400 IU eCG at PRID removal on pregnancy per AI (P/AI) in spring and autumn calving suckled beef cows, subjected to a 7-d CO-Synch + PRID timed artificial insemination (TAI) program. Suckled beef cows (n = 1408) on 62 commercial farms were enrolled and randomly assigned to either of three treatments: 1) cows received a PRID and 100 μg GnRH on Day −10, followed by 25 mg PGF2α at PRID removal (Day −3) and 100 μg GnRH 72 h later (Day 0) at TAI (Treatment 1; n: spring = 236, autumn = 248); 2) as Treatment 1, but without GnRH at PRID insertion on Day −10 (Treatment 2; n: spring = 232, autumn = 227); 3) as Treatment 1, but cows also received 400 IU eCG at PRID removal on Day −3 (Treatment 3; n: spring = 233, autumn = 232). At Day −10, ovaries were examined by ultrasonography to evaluate the presence or absence of a corpus luteum (CL) and follicle(s) ≥ 10 mm in diameter. Body condition score (BCS) was assessed on a scale of 1–5. Pregnancy diagnosis was carried out 30–35 d after TAI by transrectal ultrasonography. Data were analyzed using the GENMOD and LOGISTIC procedures of SAS. There was a treatment by season interaction for P/AI (P < 0.001). In spring, overall P/AI was 59.1% (414/701) and was affected by treatment (59.3 v 49.6 v 68.2%, for Treatments 1, 2 and 3, respectively P < 0.05). In contrast, in autumn, overall P/AI (51.5%, 364/707) was unaffected (P > 0.05) by treatment (50.1 v 53.7 v 48.7% for Treatments 1, 2 and 3, respectively). Overall, eCG had a positive effect on P/AI for cows lacking a CL at treatment initiation (P < 0.05). In addition, in cows with low BCS (≤2.25), eCG supplementation tended (P = 0.09) to improve P/AI. Seasonal differences in response to synchronization treatment may be reflective of different management regimens (grazing v confinement) and breed type and remain to be elucidated.

The Effect of PRID on the hemodynamics of preovulatory follicular, luteal and the ovarian arteries in Egyptian buffaloes

The aim of the present investigation was to study the comparative efficacy of two estrous synchronization treatments on follicular, luteal changes, and ovarian hemodynamic associated with hormonal changes of progesterone and estrogen in addition to nitric oxide. Six cyclic buffalo cows were scanned daily along three successive estrous cycles transrectal by Doppler ultrasonography to evaluate the normal ovarian hemodynamic during normal spontaneous ovulation and before the start of experiments. Buffaloes in the current study will be categorized according to the experimental design. The buffalo cows in the first experiment were synchronized with progesterone releasing intra-vaginal device (PRID) - PGF2α (7 days inserted PRID and PGF2α injected on the 6th day, n = 6). In experiment 2 the same animals (n = 6)) were taken a rest for two successive estrous cycles. Then, buffaloes were synchronized with PRID- Modified Co- synch (PRID+GnRH) in which, 7 days inserted PRID intra-virginal then animals will receive 10μg of GnRH at day 0, 250μg of PGF2α at day 7, another 10μg of GnRH administered 48h after the PGF2α injection. Blood sampling and ovarian ultrasound examinations (color and power Doppler modes) were conducted on the day of PRID removal, estrous, and luteal phase. Results revealed that buffaloes treated with PRID - PGF2α had a higher total number of follicles and F1 dominant diameter. Color Doppler ultrasonography revealed that, F1 diameter, F1 area/pixel, F1 antrum area/pixel, F1 granulosa area, and F1 colored area/pixels significantly increased in PRID -PGF2α group as compared to normal spontaneous ovulating and PRID+GnRH group. In addition, the CL diameter and their vascularity (CL Area/pixels, CL Color area/pixels, CL Color area %) were markedly increased in PRID -PGF2α group as compared to normal spontaneous ovulating and PRID+GnRH group concurrent with a high level of plasma estrogen. The higher values of resistance index (RI) of ipsilateral and contralateral ovarian arteries were recorded in PRID -PGF2α and PRID+GnRH compared to the normal spontaneous ovulating. A similar tendency was observed in blood flow volume (BFV). However, the ovarian blood flow indices including time average mean velocity (TAMV) and peak systolic velocity PSV) did not change among different groups. A higher level of plasma estrogen was achieved in PRID -PGF2α as compared to other groups. However, the progesterone levels did not vary among groups. The nitric oxide level was significantly higher in PRID+GnRH as compared to others. In conclusion, synchronization with the PRID -PGF2α protocol could be enhanced the follicular activity and hemodynamics of Egyptian buffaloes.

Subclinical mastitis interferes with ovulation, oocyte and granulosa cell quality in dairy cows

The objective was to evaluate the effect of mastitis by somatic cell count (SCC) on follicular growth, ovulation, oocytes and cumulus cells quality and on the concentration and size of exosomes in follicular fluid of dairy cows. In the study, crossbred cows (Bos taurus – Holstein x Bos indicus – Gir) were classified for analysis as Control (SCC<200.000 cells/mL) and Mastitis (SCC>400.000 cells/mL) groups. In experiment 1 (follicular dynamics), cows (n = 57) were submitted to ultrasound evaluations every 24 h, from progesterone-releasing-intravaginal-device (PRID) removal (D8) until 48 h later (D10). Thereafter, evaluations were performed every 12 h, until ovulation or up to 96 h after PRID removal. In experiment 2 (oocyte, cumulus complexes, and follicular fluid evaluation), cows (n = 26) were submitted to follicular aspiration (OPU) for oocyte quality and cumulus cells transcript evaluation. The amount of cumulus complexes transcripts (BCL2, BAX, PI3K, PTEN, FOXO3) was determined by Real-Time Polymerase Chain Reaction. Moreover, seven days after the OPU session, the dominant follicle was aspirated. Exosomes were isolated from the follicular fluid for evaluation of particle size and concentration. Ovulation rate [Control 77.4% (24/31) and Mastitis 57.7% (15/26); P = 0.09] and viable oocytes rate [Control 59.1% (130/220) and Mastitis 41.9% (125/298); P = 0.01] were higher in Control animals. Additionally, there was a greater number of degenerate oocytes [Control 6.7 ± 1.2 and Mastitis 13.3 ± 5.5; (P = 0.001)] in subclinical mastitis cows. There was greater abundance (P = 0.003) of BAX cumulus cell transcripts and exosome mean (P = 0.03) and mode (P = 0.02) was smaller in subclinical mastitis cows. In conclusion, ovulation rate, oocyte quality, and exosome diameter were smaller in cows with SCC>400.000 cells/mL.

122 TIMED ARTIFICIAL INSEMINATION IN WOOD BISON USING FROZEN-THAWED SEMEN

Recent progress with methods to control ovulation and semen cryopreservation in Wood Bison was the impetus to test the feasibility of timed AI to facilitate reclamation of this threatened species. A 2 × 2 design was used to compare the efficacy of 2 ovulation synchronization techniques and 2 semen cryopreservation protocols. Female Wood Bison were assigned randomly to 2 groups (n = 24/group) in which ovarian synchronization was induced by ultrasound-guided ablation of follicles &gt;5 mm or intramuscular treatment with 2.5 mg of estradiol 17B + 50 mg of progesterone (E+P) in canola oil. A progesterone-releasing intravaginal device (PRID) was placed at the time of follicle ablation (for 5 days) or E+P treatment (for 8 days) in the respective groups. A luteolytic dose of prostaglandin was given at the time of PRID removal, and 2500 IU of hCG was given IM 3 days later. Bison were inseminated 24 and 36 h after hCG treatment using frozen-thawed semen. The semen was collected by electro-ejaculation from 4 Wood Bison bulls, pooled, and divided into aliquots diluted in either egg-yolk extender (EY) or cholesterol-loaded cyclodextrin extender (CLC). Half the bison in each synchronization group were inseminated with either EY- or CLC-extended semen. Bison were examined by ultrasonography every 12 h beginning on the day of hCG treatment for 3 days or until ovulation was detected, whichever occurred first. Pregnancy diagnosis was made by ultrasonography 34–36 days after insemination. Two bison were excluded during the experiment because of handling difficulty; therefore, the total number of bison used was 46. Ovulation rate and interval to ovulation were compared between synchronization groups by chi-square and t-test, respectively. Pregnancy rates were compared among groups by 2-way ANOVA after transforming data to arcsin. The ovulation rate was not different between synchronization groups [combined mean, 37/46 (80%)], nor was the degree of synchrony, as assessed by the residuals (variation from the mean) in the respective groups. However, the diameter (mean ± standard error of the mean) of the dominant follicle at the time of hCG treatment was smaller in the follicle ablation group than in the E+P group (10.5 ± 0.6 v. 13.9 ± 0.6; P &lt; 0.04), and the interval from hCG treatment to ovulation tended to be longer (35.3 ± 1.6 v. 31.8 ± 1.3 h; P ≤ 0.10). Pregnancy rate was not affected by synchronization procedure, but pregnancy was detected only in the EY-inseminated group (9/23 v. 0/23; P &lt; 0.01). Despite that post-thaw sperm motility was similar for EY and CLC semen (41.7 ± 2.9 and 44.6 ± 3.3%; respectively), CLC-treated semen failed to impregnate bison in vivo. We concluded that synchronization and timed insemination with frozen-thawed semen is feasible in Wood Bison. Of the 23 bison inseminated with EY-extended semen, 21 ovulated (91%), and of those that ovulated 9 became pregnant (43%). Both synchronization schemes were effective, but the ablation protocol may be improved by an additional day between ablation and hCG treatment. We thank Vetoquinol Canada and Merck Animal Health for providing hormone treatments.

A field investigation of a modified intravaginal progesterone releasing device and oestradiol benzoate based ovulation synchronisation protocol designed for fixed-time artificial insemination of Brahman heifers

Pregnancy rates (PR) to fixed-time AI (FTAI) in Brahman heifers were compared after treatment with a traditional oestradiol-based protocol (OPO-8) or a modified protocol (OPO-6) where the duration of intravaginal progesterone releasing device (IPRD) was reduced from 8 to 6 days, and the interval from IPRD removal to oestradiol benzoate (ODB) was increased from 24 to 36h. Rising 2 yo heifers on Farm A: (n=238 and n=215; two consecutive days AI); B (n=271); and C (n=393) were allocated to OPO-8 or OPO-6. An IPRD was inserted and 1mg ODB i.m. on Day 0 for OPO-8 heifers and Day 2 for OPO-6 heifers. On Day 8, the IPRD was removed and 500μg cloprostenol i.m. At 24h, for OPO-8 heifers, and 36h, for OPO-6 heifers, post IPRD removal all heifers received 1mg ODB i.m. FTAI was conducted at 54 and 72h post IPRD removal for OPO-8 and OPO-6 heifers. At Farm A, OPO-6 heifers, AI on the second day, the PR was 52.4% to FTAI (P=0.024) compared to 36.8% for OPO-8 heifers. However, no differences were found between OPO-8 and OPO-6 protocols at Farm A (first day of AI) (39.9 vs. 35.7%), or Farms B (26.2 vs. 35.4%) and C (43.2% vs. 40.3%). Presence of a corpus luteum at IPRD insertion affected PR to FTAI (43.9% vs. 28.8%; P<0.001). This study has shown that the modified ovulation synchronisation protocol OPO-6 may be a viable alternative to the OPO-8 protocol for FTAI in B. indicus heifers.

Effect of initial GnRH and duration of progesterone insert treatment on the fertility of lactating dairy cows.

The study compared response to prostaglandin F2α (PG), synchrony of ovulation and pregnancy per AI (P/AI) in a 5- vs a 7-day Ovsynch+PRID protocol and investigated whether the initial GnRH affects P/AI in lactating dairy cows. Two hundred and seventy-six cows (500 inseminations) were assigned to one of four timed-AI (TAI) protocols: (i) PRID-7G; 100μg GnRH im, and a progesterone-releasing intravaginal device (PRID) for 7days. At PRID removal, PG (500μg of cloprostenol) was given im. Cows received the second GnRH treatment at 60h after PRID removal and TAI 12h later. (ii) PRID-5G; as PRID-7G except the duration of PRID, treatment was 5days and PG was given twice (12h apart). (iii) PRID-7NoG; as PRID-7G except the initial GnRH, treatment was omitted. (iv) PRID-5NoG; as PRID-7NoG except the duration of PRID, treatment was 5days. Response to treatments and pregnancy status at 32 and 60days after TAI was determined by ultrasonography. The percentage of cows ovulating before TAI was greatest in PRID-7G (17.1%), and the percentage of cows that did not have luteal regression was greatest in PRID-5G (9.5%). The overall P/AI at 32 and 60days did not differ among TAI protocols. However, during resynchronization, cows subjected to the 5-day protocols had greater (p<0.05) P/AI (45.3% vs 33.6%) than cows subjected to the 7-day protocols. Pregnancy loss between 32 and 60days tended (p=0.10) to be greater in cows that did not receive initial GnRH (14.8%) compared to those that received GnRH (8.2%). In conclusion, the PRID-5G protocol resulted in fewer cows responding to PG, but P/AI did not differ among TAI protocols. A 5-day protocol resulted in more P/AI in resynchronized cows, and cows that did not receive initial GnRH tended to experience more pregnancy losses.

Successful induction of oestrus, ovulation and pregnancy in adult ewes and ewe lambs out of the breeding season using a GnRH + progesterone oestrus synchronisation protocol

A series of experiments was designed to assess the effect of a treatment protocol (U-synch) for inducing oestrus and ovulation out of the breeding season in adult ewes and ewe lambs. The protocol consisted of a 7-day treatment with an intravaginal progesterone-releasing device (IPRD), administration of GnRH at IPRD insertion on Day 0, and equine chorionic gonadotropin (eCG) and prostaglandin F2α at IPRD removal on Day 7. In Experiment 1, 50 or 100μg GnRH were sufficient to induce ovulation at the beginning of the protocol in 3/9 and 4/9 ewes, respectively; while the resulting proportion of sheep ovulating after the treatment protocol was 88.9% and 77.8% in ewes initially treated with 50 or 100μg GnRH, respectively. In Experiment 2, the proportion of Romney-cross ewe lambs ovulating was greater (P<0.0001) in the U-synch group (95.4%) than in the untreated Control group (3.2%). In Experiment 3, pregnancy rates of Dorset-cross sheep in the U-synch (60.7%) and Standard (12-day IPRD and eCG treatment; 56.5%) groups were greater (P=0.01) than in the untreated Control group (43.4%). The incidence of twin pregnancies was greater (P=0.005) in the U-synch group than in the Control group. A 7-day IPRD treatment including GnRH treatment at device insertion and eCG treatment at device removal induced oestrus and ovulation during the non-breeding season in a high proportion of mature ewes and ewe lambs. High pregnancy rates to natural mating, with a low rate of triplet pregnancies, were also observed.

Fate of follicular ovarian cysts in early postpartum dairy cows treated with PRID/PGF or PRID/PGF plus eCG.

To ultrasonographically investigate the effect of administration of exogenous progesterone using a progesterone-releasing intravaginal device (PRID), with or without the addition of equine chorionic gonadotropin (eCG), to cows with cystic ovarian disease (COD) in the first month postpartum. Thirty-three dairy cows (n=11/group) diagnosed with COD between day20 and 30 postpartum were randomly assigned to treatment groups (TG) PRID/PGF and PRID/PGF+eCG or a control group (CG). The CG remained untreated during the 20-day study period, which started on the day the diagnosis was made (day0). Cows of group PRID/PGF received a PRID, which was removed on day10, at which time PGF2α was given intravenously. Cows of the PRID/PGF+eCG group additionally received eCG on day7 intravenously. Ovarian ultrasonography and blood sampling for measurement of plasma progesterone (P4) and estradiol-17β (E2) were done on days 0, 7, 10, 13, and 20 in the TG and on days 0, 10, and 20 in the CG. On day0, all cows had follicular cysts, six of which developed into luteal cysts in the CG. The mean cyst diameter remained unchanged in the CG and decreased in the TG by day20 (p<0.01). All treated cows ovulated and formed at least one corpus luteum (CL) after PRID removal, but only two control cows ovulated (p<0.05). Of 12 ovulatory follicles in the TG dominant on day7, eight formed a CL with a cavity, whereas of 10 ovulatory follicles in the same groups, dominant on day10, only one formed a CL with a cavity (p<0.05). The diameters of follicles, that formed a CL with a cavity, were larger on day10 (p<0.01). Mean P4 concentrations on day0 were ≤1ng/ml in all groups. P4 concentration increased during treatment and decreased below 1ng/ml after PRID removal (p<0.05). Treatment with PRID alone led to resolution of COD in all cows and therefore the additional benefit of eCG could not be critically assessed. CL with a cavity more often originate from larger and older dominant ovulatory follicles.

Ovarian dynamics in response to two modified intravaginal progesterone releasing device and oestradiol benzoate based ovulation synchronisation protocols designed for use in Brahman heifers

The objective was to investigate the ovarian response of Brahman heifers to two modified ovulation synchronisation protocols developed to increase the proportion of normal synchronous ovulations. Experiment 1 characterised the growth of the ovulatory follicle in heifers (n=19) treated with an intravaginal progesterone releasing device (IPRD) and oestradiol benzoate (ODB), to determine the optimal time to induce ovulation. Using the findings from Experiment 1, Experiment 2 investigated the effect of reducing the duration of IPRD insertion and increasing the interval from IPRD removal to ODB treatment (modified protocol 1 – OPO-6; n=20), and omitting ODB treatment at the time of IPRD insertion (modified protocol 2 – PO-6; n=20). An IPRD (0.78g progesterone) was inserted at Day 0 (OPO-8) or Day 2 (OPO-6 and PO-6) and all heifers also received 1mg ODB i.m. Day 8: IPRD removed+500μg cloprostenol i.m. At 24h (OPO-8) and 36h (OPO-6 and PO-6) post IPRD removal: 1mg ODB i.m. Fixed-time AI (FTAI) occurred at 54h for OPO-8 and 72h for OPO-6 and PO-6, post IPRD removal. After IPRD treatment all OPO-6 and OPO-8 heifers initiated a new follicular wave whereas 25% of PO-6 heifers failed. Diameter of the dominant follicle was larger at FTAI in the PO-6 (11.34±0.50mm) compared to the OPO-8 protocol (9.74±0.51mm; P<0.05), but similar to the OPO-6 protocol (10.52±0.51mm). Proportion of ovulations occurring 12h prior and 24h post FTAI was similar for the PO-6 (80%) and OPO-6 (75%) protocols but numerically lower in the OPO-8 heifers (60%). The apparent improvement in ovarian response in heifers treated with the modified protocols needs to be confirmed in larger field studies.

Lengthening the superstimulatory treatment protocol increases ovarian response and number of transferable embryos in beef cows

This study determined if lengthening the superstimulation protocol from 4 to 7 days would result in an increase in the superovulatory response with no adverse effects on oocyte/embryo competence in beef cows. Follicular ablation was performed, a progesterone-releasing intravaginal device (PRID) was inserted, and cows were assigned to one of two treatment groups 5 to 8 days after ovulation: Control (4 days of follicle stimulating hormone (FSH)) or Long (7 days of FSH; n = 12 per group). The FSH treatments were initiated 1.5 days later (Day 0). A dose of 400 mg NIH-FSH-P1 (Folltropin-V) was distributed equally over 8 (Control) or 14 (Long) im injections at 12-h intervals. Prostaglandin F2α (PGF) was administered twice, 12 h apart, on Day 2 (Control) or Day 5 (Long), and PRID were removed 12 h after the second PGF. Both groups were given 25 mg pLH (lutropin-V) im 24 h after PRID removal and AI was done 12 and 24 h later. Ova/embryos were collected 7 days after the pLH injection. The mean (± SEM) number of ≥ 9 mm follicles at the time of first AI did not differ (P = 0.24) between groups, but more ovulations (30.9 ± 3.9 vs. 18.3 ± 2.9, P = 0.01) and CL (27.2 ± 2.1 vs. 20.8 ± 2.2, P = 0.04) occurred in the Long group. A higher proportion of the ≥ 9 mm follicles ovulated between 12 and 36 h after pLH in the Long group (93 vs. 69%; P = 0.001). Although numerically higher in the Long group, mean numbers of total ova/embryos, fertilized ova, transferable or freezable embryos did not differ. In conclusion, a lengthened superstimulatory treatment protocol resulted in more follicles acquiring the capacity to ovulate with an increased number of ovulations, and without a decrease in oocyte/embryo competence.

Ovarian responses in Bos indicus heifers treated to synchronise ovulation with intravaginal progesterone releasing devices, oestradiol benzoate, prostaglandin F 2α and equine chorionic gonadotrophin

The objectives were: (i) improve understanding of the ovarian responses of Bos indicus heifers treated with different ovulation synchronisation protocols, (ii) compare ovarian responses of B. indicus heifers treated with intravaginal progesterone releasing device (IPRD) + oestradiol benzoate (ODB) versus a conventional prostaglandin F 2α (PGF 2α) protocol and (iii) investigate whether reducing the amount of progesterone (P 4) in the IPRD, and treatment with equine chorionic gonadotrophin (eCG) would increase the proportion of heifers with normal ovarian function during the synchronised and return cycles. Two-year-old Brahman ( n = 30) and Brahman-cross ( n = 34) heifers were randomly allocated to three IPRD-treatment groups: (i) standard-dose IPRD (Cue-Mate ® 1.56 g P 4; n = 17); (ii) half-dose IPRD (Cue-Mate ® 0.78 g P 4; n = 15); (iii) half-dose IPRD + 300 IU eCG at IPRD removal ( n = 14), and a non-IPRD control group (iv) 2 × PGF 2α (500 μg cloprostenol) on Days −16 and −2 ( n = 18). IPRD-treated heifers received 250 μg cloprostenol at IPRD insertion (Day −10) and IPRD removal (Day −2) and 1 mg ODB on Days −10 and −1. Ovarian function was evaluated by ultrasonography and plasma P 4 throughout the synchronised and return cycles. The mean diameter of the dominant follicle observed at 54–56 h after IPRD removal, was greater for heifers which ovulated than heifers which did not ovulate ( P < 0.001; 14.5 ± 1.1 vs. 9.3 ± 0.6 mm, respectively). The prevalence of IPRD-treated heifers with ovarian dysfunction (persistent CL, failure to re-ovulate, shortened luteal phase) was 39%. This relatively high prevalence of ovarian dysfunction may explain the commonly reported, lower than expected pregnancy rates to FTAI in B. indicus heifers treated to synchronise ovulation.

Animal‐Level Factors Affecting Ovarian Function in Bos indicus Heifers Treated to Synchronize Ovulation with Intravaginal Progesterone‐Releasing Devices and Oestradiol Benzoate

The primary objective of this study was to investigate the impact of animal-level factors including energy balance and environmental/management stress, on the ovarian function of Bos indicus heifers treated to synchronize ovulation. Two-year-old Brahman (BN) (n = 30) and BN-cross (n = 34) heifers were randomly allocated to three intravaginal progesterone-releasing device (IPRD) treatment groups: (i) standard-dose IPRD [Cue-Mate(®) (CM) 1.56 g; n = 17]; (ii) half-dose IPRD [0.78 g progesterone (P(4)); CM 0.78 g; n = 15]; (iii) half-dose IPRD + 300 IU equine chorionic gonadotrophin at IPRD removal (CM 0.78 g + G; n = 14); (iv) and a control group, 2× PGF(2α) [500 μg prostaglandin F(2α) (PGF(2α))] on Day -16 and -2 (n = 18). Intravaginal progesterone-releasing device-treated heifers received 250 μg PGF(2α) at IPRD insertion (Day -10) and IPRD removal (Day -2) and 1 mg oestradiol benzoate on Day -10 and -1. Heifers were managed in a small feedlot and fed a defined ration. Ovarian function was evaluated by ultrasonography and plasma P(4) throughout the synchronized and return cycles. Energy balance was evaluated using plasma insulin-like growth factor 1 (IGF-I) and glucose concentrations. The impact of environmental stressors was evaluated using plasma cortisol concentration. Heifers that had normal ovarian function had significantly higher IGF-I concentrations at commencement of the experiment (p = 0.008) and significantly higher plasma glucose concentrations at Day -2 (p = 0.040) and Day 4 (p = 0.043), than heifers with abnormal ovarian function. There was no difference between the mean pre-ovulatory cortisol concentrations of heifers that ovulated or did not ovulate. However, heifers that ovulated had higher cortisol concentrations at Day 4 (p = 0.056) and 6 (p = 0.026) after ovulation than heifers that did not ovulate.

319 SUPEROVULATORY RESPONSE IN JAPANESE BLACK CATTLE BY A SINGLE SUBCUTANEOUS ADMINISTRATION OF PURE FOLLICLE-STIMULATING HORMONE DISSOLVED IN SALINE

The objective of this study was to evaluate the superovulatory response to a single SC administration of pFSH (Antrin R-10) dissolved in saline in Japanese Black cattle. Forty Japanese Black cows were divided into 5 groups. All cows received a progesterone releasing intravaginal device (PRID) at a random stage of the oestrous cycle except the day of oestrus (Day 0). Superovulatory treatments were initiated on Day 4 with single SC administration of 20 AU pFSH dissolved in 10 mL of saline (Group A) or 50 mL of saline (Group B), or 30 AU pFSH dissolved in 10 mL of saline (Group C) or 50 mL of saline (Group D). Conventional superovulatory treatment (Group E) was also initiated on Day 4 with 20 AU pFSH in decreasing doses in IM administration twice a day for 3 days (5/5, 3/3, and 2/2 in the am/pm). Each administration was carried out in the neck region. For oestrus induction, all animals were treated with prostaglandin F2α (750 μg of cloprostenol) on Day 4, and then the PRID was removed on Day 6 in the morning. The GnRH (10 μg of buserelin) was administrated at 31 h after PRID removal to induce ovulations. The cows were artificially inseminated at 24 h after GnRH treatment, and embryos were recovered 7 days after the insemination. Blood samples were collected at 0, 2, 4, 6, 8, 10, 24, 31, 48, 55, 72, and 79 h after the first pFSH administration, and serum pFSH concentration was measured using time-resolved fluorescence immunoassay. Percentage data were arcsine transformed before analysis, and one-way ANOVA was used for statistical analysis (P &lt; 0.05). There were no significant (P &gt; 0.05) differences among groups in the number of corpus luteum, total number of ova/embryos, number of transferable embryos, and percentage of transferable embryos. The concentrations of pFSH in serum increased in all groups 2 h after each administration and reached a peak at 8 h in Groups A and C, at 10 h in Groups B, D, and E, and then in all groups it decreased gradually. The concentrations of pFSH in serum decreased to the base level (the level at 0 h) in Group A at 55 h and in Group C at 72 h after the first pFSH administration. At 79 h, serum pFSH was still detected in Groups B, D, and E. These results suggest that the single SC administration of 20 AU pFSH that is the same dose as the conventional treatment is able to induce a superovulatory response comparable to that of conventional treatment in Japanese Black cattle. Table 1.Superovulatory responses (mean ± SE) in different treatment groups

Estrus Synchronization and Conception Rate after a Progesterone Releasing Intravaginal Device (PRID) Treatment from the Early Luteal Phase in Heifers

The objective of the present study was to evaluate estrus synchronization and conception rate after progesterone releasing intravaginal device (PRID) treatment from the early luteal phase in the presence or absence of estradiol benzoate (EB) in heifers. Heifers (n=11) were assigned randomly to two treatments; insertion of a PRID containing 1.55 g progesterone with a capsule attached including 10 mg EB (P+EB; n=6) and the PRID withdrawn the EB capsule (P-EB; n=5). The PRID was inserted into the vagina on Day 2 of the estrous cycle (Day 0 was the day of ovulation) and was left for 12 days. The proportion of heifers exhibiting standing estrus within 3 days after PRID removal was 83.3% (5/6) for the P+EB group, and 80.0% (4/5) for the P-EB group, respectively. Conception rate by artificial insemination on synchronized estrus was 80.0% (4/5) in the P+EB group, and 100% (4/4) in the P-EB treatment group, respectively. These results suggest that a PRID treatment from 2 days after ovulation for 12 days in the presence or absence of EB has an effect on the synchronization of estrus and produces a beneficial conception rate in heifers.

The therapeutic effects of a progesterone-releasing intravaginal device (PRID) with attached estradiol capsule on ovarian quiescence and cystic ovarian disease in postpartum dairy cows.

The objective of this study was to evaluate the effects of a progesterone-releasing intravaginal device (PRID) containing an estradiol benzoate capsule on ovarian dysfunction, including ovarian quiescence, follicular cyst (FC) and luteal cyst or cystic corpus luteum (LC/CCL), in postpartum dairy cows. These ovarian dysfunctions were examined by palpation per rectum relative to plasma progesterone status. The results of clinical examination and hormone assay determined ovarian quiescence in 13 cows, FC in 15 cows and LC/CCL in 7 cows. These cows were treated with PRID for 12 d and then clinical examination was performed. After PRID removal, the proportion of cows exhibiting estrous signs within 7 d and confirmed formation of CL within 7-14 d (markedly effective) were 69.2 % (n=9) for ovarian quiescence, 46.7 % (n=7) for FC, and 28.6 % (2 cows) for LC/CCL. Two cows (15.4 %) in ovarian quiescence, 5 cows (33.3%) with FC and 4 cows (57.1 %) with LC/CCL did not exhibit estrous signs but were recognized as having formed CL within 12-16 d after removal of PRID (effective). These results suggest that treatments of PRID with estradiol benzoate for 12 d have therapeutic efficacy on ovarian dysfunction including ovarian quiescence, FC and LC/CCL in postpartum dairy cows.

Ovarian follicular dynamics and hormonal profiles in heifer and mixed-parity Mediterranean Italian buffaloes ( Bubalus bubalis) following an estrus synchronization protocol

The primary objective was to elucidate ovarian follicular dynamics and hormonal profiles in nulliparous heifer (HE; n=11) and mixed-parity (MP; n=10) Mediterranean Italian water buffaloes ( Bubalus bubalis) following an estrus synchronization protocol. Both groups received a progesterone releasing intravaginal device (PRID) implant for 10 days; a luteolytic dose of synthetic prostaglandin was given 7 days after PRID insertion. Daily ultrasound monitoring and collection of blood to determine plasma concentrations estradiol and progesterone started 1 day after PRID removal and lasted for 55 and 65 days in HE and MP buffaloes, respectively. Data analysis was restricted to the first 5 days after PRID removal and to one estrus cycle following induced ovulation. The HE buffaloes were not inseminated and only one ovulated within 5 days after PRID removal; the remainder ovulated between 8 and 48 days after PRID removal (except one in which ovulation was never detected). All HP buffaloes were inseminated 72, 96 and 120 h after PRID removal; seven buffaloes ovulated within 5 days after PRID removal and two were pregnant. Mean diameter of the largest follicle was significantly smaller in HE than MP buffaloes the first 4 days after PRID removal. There was a parity by time interaction ( P=0.0047) for plasma progesterone concentrations; progesterone was higher in HE than MP buffaloes 1 day after PRID removal, but the converse was true 2 days after PRID removal. After induced ovulation, HE buffaloes exhibited a one-wave ( n=5; length of cycle, 8–12 days), two-wave ( n=4; range: 20–26 days) or three-wave cycle ( n=1; 25 days). In contrast, all non-pregnant MP buffaloes ( n=8) had a two-wave cycle (range: 19–25 days). For buffaloes with two-wave cycles, the growth rate and diameter of the largest follicle was significantly smaller in HE than MP buffaloes for both the first follicular wave (1.3 mm versus 1.7 mm per day and 10.5 mm versus 13.3 mm, respectively) and the second follicular wave (1.0 mm versus 1.3 mm per day and 11.0 mm versus 13.8 mm). In conclusion, there were many significant morphological and endocrine differences between HE and MP buffaloes.

Luteal activity at the onset of a timed insemination protocol affects reproductive outcome in early postpartum dairy cows

This study was designed to compare two timed insemination protocols, in which progesterone, GnRH and PGF2α were combined, with the Ovsynch protocol in presynchronized, early postpartum dairy cows. Reproductive performance was also evaluated according to whether cows showed high or low plasma progesterone concentration, at the onset of treatment. One hundred and six early postpartum dairy cows were presynchronized with two cloprostenol treatments given 14 days apart, and then assigned to one of the three treatment groups. Treatments for the synchronization of estrus in all three groups started 7 days after the second cloprostenol injection, which was considered Day 0 of the actual treatment regime. Cows in the control group (Ovsynch, n=30) were treated with GnRH on Day 0, PGF2α on Day 7, and were given a second dose of GnRH 32 h later. Cows in group PRID ( n=45) were fitted with a progesterone releasing intravaginal device (PRID) for 9 days, and were given GnRH at the time of PRID insertion and PGF2α on Day 7. In group PRID/GnRH ( n=31), cows received the same treatment as in the PRID group, but were given an additional GnRH injection 36 h after PRID removal. Cows were inseminated 16–20 h after the administration of the second GnRH dose in the Ovsynch group, and 56 h after PRID removal in the PRID and PRID/GnRH groups. Ovulation rate was determined on Day 11 postinsemination by detecting the presence of a corpus luteum in the ovaries. Lactation number, milk production, body condition at the onset of treatment and treatment regime were included as potential factors influencing ovulation and pregnancy after synchronization. Logistic regression analysis for cows with high and low progesterone concentration on treatment Day 0 revealed that none of the factors included in the models, except the interaction between progesterone and treatment regime, influenced the risk of ovulation and pregnancy significantly. In cows with high progesterone concentration at treatment onset, Ovsynch treatment resulted in a significantly improved pregnancy rate over values obtained following PRID or PRID/GnRH treatment. In cows with low progesterone concentration, PRID or PRID/GnRH treatment led to markedly increased ovulation and pregnancy rates with respect to Ovsynch treatment. These findings suggest the importance of establishing ovarian status in early postpartum dairy cows before starting a timed AI protocol, in terms of luteal activity assessed by blood progesterone.