Controlled Internal Drug Release Group Research Articles

Timing of ovulation in the fat-tailed Qezel ewes after synchronization with vaginal devices containing endogenous or exogenous synthetic progestogens during out of the breeding season.

Wide range of ovulation distribution is the main restricting factor in establishing the pregnancy following oestrus synchronization (ES) and fixed time insemination (FTI) in sheep. Determining the ovulation time (OVT) following ES with two different vaginal devices, its relation to progesterone and conception upon FTI with frozen/thawed semen. Oestrus was synchronized using either controlled internal drug release (CIDR) (ewe, n=6; ewe lamb, n=5) or vaginal sponge (ewe, n=6; ewe lamb, n=5) insertion for 12 days, plus Equine chorionic gonadotropin (eCG) at devices removal (Day 0). Sizes of the ovarian follicles were measured using transvaginal probe at -12, 0 and 30-33, 53h and continued every 3-4h until 75h after eCG treatment. Serum progesterone amounts were measured at -12, 0, +2 and +11. Laparoscopic FTI was done at 60.5±0.5h. The CIDR-treated group initiated and completed ovulations earlier compared to sponge-treated females (median: 64 vs. 71h; p<0.05). Ewe lambs were ovulated earlier compared to ewes in the sponge-treated group (66.71 vs. 71.5; p=0.017). Mean sizes of ovulatory follicles and corpora lutea were not affected by device types. Higher amounts of progesterone were observed in CIDR group compared to sponge-treated group at device removal (2.68±0.12 vs. 0.30±0.01ng/mL; p<0.001). The conception was confirmed in 2/10, and 5/11 females of sponge and CIDR-treated females, respectively. Types of progestogens influence the OVT, and consequently the result of FTI with frozen/thawed semen. The optimum timespan for FTI should be chosen according to the device types during non-breeding season.

ESTROGEN HORMONE PROFILE AND ESTRUS RESPONSE OF THIN TAILED EWES SYNCHRONIZED WITH CONTROLLED INTERNAL DRUG RELEASE

This research was conducted to identify the estrogen hormone profile and estrus response in the thin tailed ewes synchronized with controlled internal drug release (CIDR) implant. This research was carried out by employing 8 thin tailed ewes, CIDR, and estrogen kit. The ewes were distributed into: 3 ewes as control group and 5 ewes as treated group (with 12 days-CIDR implantation). Ewes were raised in the Sidomukti farm group, Sleman Regency, Yogyakarta. The data obtained were estrogen hormone profile during estrus examined by using ELISA method and estrus response marked with the reddening and oedema of vulva, mucus vaginal discharge, behavioral changes, vaginal pH, and superficial cells population. The data were analyzed by applying independent sample T-test. The result did not show any significant difference (P0.05) in the normal range between the control and CIDR group in estrogen hormone profile, estrus response, and pH level, but showed significant differences with positive correlation (P0.05) in population of superficial cells. In conclusion, CIDR was an effective tool for estrus synchronization at the farmer group, and gave positive estrus response towards thin tailed ewes with estrogen hormone profile, pH level, and superficial cell percentage on the normal range.

Controlled Internal Drug Release (CIDR) Based Hormonal Protocols Effect upon Estrus Response and Pregnancy Outcome in Anestrous Cows

Controlled internal drug release (CIDR) based hormonal protocols CoSynch + CIDR, OvSynch + CIDR and CIDR + PGF2α were applied to 25 crossbred anestrous Holstein and Jersey cows to improve the fertility at the farm of National Cattle Research Programme, Rampur, Chitwan. All three protocols were found equally effective (P&gt;0.05) with 100% estrus expression rate, out of which, 80% (8/10), 85.7% (6/7) and 75% (6/8) had estrus expression with well cervix open at fixed time artificial insemination in CoSynch + CIDR, OvSynch + CIDR and CIDR + PGF2α protocols respectively and rest had estrus expression with partial cervix open. Statistically non-significant (P&gt;0.05) pregnancy outcome that is 14.3 % (1/7) in CIDR+PGF2α group and 12.5 % (1/8) in OvSynch group while none in CoSynch + CIDR group were pregnant following fixed time artificial insemination. Poor pregnancy outcome of the anestrous cows in all protocols might not only have hormonal problem but also could have various other reasons which was beyond the objective of this research findings. Hence, study concludes anestrous cows respond well to the CIDR based hormonal protocols to revive the estrus.&#x0D;

Comparison of 4- versus 5-day Co-Synch + controlled internal drug release (CIDR) + timed artificial insemination protocols in dairy heifers

The objective of this study was to compare the pregnancy rate after timed artificial insemination (P/TAI) in dairy heifers treated with 4- versus 5-day Co-Synch + controlled internal drug release (CIDR) protocols. A total of 120 Holstein heifers were randomly assigned to one of two groups. The heifers received an intravaginal CIDR insert containing 1.38 g of progesterone for 4 days (Monday–Friday 4-day Co-Synch + CIDR; n = 60) or 5 days (5-day Co-Synch + CIDR; n = 60). At the time of CIDR removal, 25 mg of PGF2α was injected intramuscularly, and 72 hours after CIDR removal, the heifers received 100 μg of GnRH intramuscularly and were artificially inseminated. Artificial insemination was performed by an experienced technician, using commercial frozen–thawed semen from a single sire. Pregnancy diagnosis was performed by ultrasonography per rectum 32 days after TAI. Categorical data were analyzed using proc logistic and the chi-square test, whereas continuous variables were analyzed using the t-test of Statistical Analysis Systems. Heifers in the 4-day Co-Synch + CIDR group had an acceptable P/TAI32 (55.0%, 33 of 60), which was not different (P = 0.35) from that observed in the 5-day Co-Synch + CIDR group (63.3%, 38 of 60). Progesterone concentration at CIDR insertion or estradiol concentration at TAI did not influence the pregnancy outcomes. Interestingly, estradiol concentration at TAI was greater in the 4-day Co-Synch + CIDR group compared to the 5-day Co-Synch + CIDR group (P < 0.01). In conclusion, the Monday to Friday 4-day Co-Synch + CIDR protocol resulted in adequate P/TAI in dairy heifers, which was similar to that of the 5-day Co-Synch + CIDR protocol. This novel protocol might represent a promising hormonal treatment for TAI in dairy heifers, facilitating their reproductive management routine, while maintaining an adequate fertility.

Use of fluorogestone acetate sponges or controlled internal drug release for estrus synchronization in ewes: Effects of hormonal profiles and reproductive performance

This study was carried out using 300 multiparous Najdi ewes during breeding season to compare the effects of fluorogestone acetate (FGA) sponges and controlled internal drug release (CIDR) dispensers to synchronize estrus on reproductive performance and hormonal profiles. Ewes were equally and randomly allotted into group A (FGA) and group B (CIDR); intravaginal progestagen was administered for 14-day period with intramuscular administration of 600-IU eCG at withdrawal time. Estrus was detected using a vasectomized ram starting 12 hours after progestagen withdrawal and repeated every 12 hours up to 84 hours. Blood samples were collected at the time of progestagen withdrawal (0 hour), 24 hours, and 48 hours. Follicle-stimulating hormone, LH, estradiol, and progesterone serum concentrations were measured using commercial ELISA kits and microtitrimetric plates. Timed laparoscopic insemination was performed 48 hours after progestagen withdrawal. Pregnancy and the number of fetuses were diagnosed by ultrasonography on Day 23 after insemination and confirmed on Days 35 and 60. The results revealed that the retention, vaginal discharge, and drawstring breakage rates after progestagen removal were significantly (P ≤ 0.05) higher in the FGA group (94.00, 98.58, and 9.22, respectively) than those in the CIDR group. On the other hand, pregnancy, fertility, twinning rates, and fecundity were significantly (P ≤ 0.05) higher in the CIDR group (77.86, 75.57, 34.34, and 1.02, respectively) than in the FGA group. Estrus responses in FGA and CIDR groups increased gradually to attain their significantly (P ≤ 0.05) higher percentages after 48 hours of progestagen withdrawal (91.49 and 92.37, respectively); thereafter, they decreased. The overall estrus responses and prolificacy did not differ between the FGA and CIDR groups. Follicle-stimulating hormone was significantly higher in the FGA group at 24 and 48 hours after progestagen withdrawal, whereas LH was significantly higher in the CIDR group at 48 hours after progestagen withdrawal. Estradiol and progesterone were significantly higher in the CIDR group at 0, 24, and 48 hours after progestagen withdrawal. These results indicated that although FGA and CIDR devices are efficient in synchronizing estrus in ewes, CIDR provided higher pregnancy, fertility, twinning rates, and fecundity than FGA.

OVARIAN RESPONSE OF DAIRY COWS TO PROGESTERONE COMBINED ON

The objective of this study was to evaluate the response of ovaries in estrus synchronizationprotocol using GnRH-PGF2α based protocol combined progestin in a herd with tie-stall housing system.A total of 20 Holstein Friesian cows at different stages of estrus cycle in a dairy herd were enrolled inthe present study. The cows were randomly allocated into two treatment groups; with and without CIDR(Controlled internal drug release) insertion. All cows received 100 μg of GnRH I.M. at the beginning ofthe treatment (d 0) without regard to the stages of the estrus cycle followed by 25 mg PGF2α IM 7dayslater. Cows in CIDR group were inserted CIDR into the vagina at the time of GnRH administration andwere removed on the day of PGF2α administration. estrus signs were checked twice daily starting onday-2 after initiation of the protocol, except cows in CIDR group the estrus signs were checked startingon day-8 of the protocol. The animals showing estrus signs were noted. Blood samples were collectedfrom all animals on the days of GnRH and PGF2α treatments and on day-10 after initiation of protocolfor progesterone concentration. The results of this study showed that 30% animals in cows withoutCIDR insertion showed estrus signs prior to PGF2α injection. Involving CIDR to synchronized estruswith GnRH-PGF2α based protocol avoided the occurrence of premature estrus and maintained highprogesterone concentration on the day of PGF2α administration. It is concluded that ovarian responseafter involving CIDR in the protocol for estrus synchronization especially using combination of GnRHand PGF2α were much effective to synchronize the initiation of estrus in dairy cows. Likewise, the useof progesterone avoided premature estrus.

Fertility in Angus cross beef cows following 5-day CO-Synch + CIDR or 7-day CO-Synch + CIDR estrus synchronization and timed artificial insemination

The present study determined whether a 5-day CO-Synch + controlled internal drug release (CIDR) protocol with two doses of PGF2α would improve timed artificial insemination (AI) pregnancy rate compared with 7-day CO-Synch + CIDR protocol in beef cows. Angus cross beef cows (N = 1817) at 12 locations were randomly assigned to 5-day CO-Synch + CIDR or 7-day CO-Synch + CIDR groups. All cows received 100 μg of GnRH and a CIDR insert on Day 0. Cows (n = 911) in the 5-day CO-Synch + CIDR group received two doses of 25 mg PGF, the first dose given on Day 5 at CIDR removal and the second dose 6 hours later, and 100 μg GnRH on Day 8 and were inseminated concurrently, 72 hours after CIDR removal. Cows (n = 906) in 7-day CO-Synch + CIDR group received 25 mg of PGF at CIDR removal on Day 7, and 100 μg GnRH on Day 10 and were inseminated concurrently, 66 to 72 hours after CIDR removal. All cows were fitted with a heat detector aid at CIDR removal and were observed twice daily until insemination for estrus and heat detector aid status. Accounting for estrus expression at or before AI (P < 0.0001) and body condition score (P < 0.01), cows in the 5-day CO-Synch + CIDR group had greater AI pregnancy rate compared with cows in the 7-day CO-Synch + CIDR group (58.1% vs. 55.1%; P = 0.04). More cows that exhibited estrus at or before AI became pregnant compared with cows that did not [65.7% (681/1037) vs. 44.5% (347/780); P < 0.0001]. The AI pregnancy rate was lesser for cows with body condition ≤4 [≤4 − 49.3% (101/219), 5–6 − 57.9%; >6 − 55.8%]. The mean AI pregnancy rate difference between treatment groups and projected economic outcome varied among locations. In conclusion, cows synchronized with the 5-day CO-Synch + CIDR protocol had greater AI pregnancy rate than those that received the 7-day CO-Synch + CIDR protocol.

Intravaginal Progesterone Devices in Synchronization Protocols for Artificial Insemination in Beef Heifers

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.

Comparison of the effects of gonadotropin-releasing hormone, human chorionic gonadotropin or progesterone on pregnancy per artificial insemination in repeat-breeder dairy cows

Three different treatments were compared to improve pregnancy per artificial insemination (P/AI) in repeat-breeder (RB) dairy cows. All cows ( n = 103) were assigned to one of four groups: (1) gonadotropin-releasing hormone (GnRH); (2) human chorionic gonadotropin (hCG); (3) once-used controlled internal drug release (CIDR) device; and (4) control. All treatments performed 5–6 days after artificial insemination (AI) and milk samples were collected just before treatment for progesterone assays. There were no significant differences in milk fat progesterone concentration among trial groups. Cows were observed for estrus signs thrice daily. Pregnancy per AI on day 45 in hCG and CIDR groups were significantly higher than GnRH and control groups (60.0% and 56.0% vs. 26.9% and 29.6%, respectively), but there were no differences in P/AI between GnRH and control groups. There were also no significant differences between hCG and CIDR groups. Milk fat progesterone concentrations were compared between pregnant and non-pregnant cows in each group and only in the hCG group it was significantly lower in pregnant cows. In conclusion, treating repeat-breeder cows with hCG or once-used CIDR 5–6 days after AI improved P/AI.

Effects of Breed and Progestin Source on Estrus Synchronization and Rates of Fertility and Fecundity in Iranian Sanjabi and Lori Ewes

A trial was conducted to evaluate the effects of FGA (Fluorogestone acetate) and CIDR (Controlled internal drug release) on the induction of estrus and pregnancy and fecundity rates of the Sanjabi and Lori sheep. A total of 360 Sanjabi and Lori sheep were randomly grouped into two treatments with intravaginal devices inserted for 13 days: Group FGA (40 mg FGA, n = 180) and Group CIDR (n = 180). All ewes received an i.m. injection of 400 IU eCG (equine chorionic gonadotrophin) at devices removal. Estrous was assessed by exposing all ewes to vasectomized rams at 12 h intervals. Cervical artificial insemination was performed 12 h after estrus onset. The overall estrus response was 72.5%. The source of progestin did not influence the efficiency of estrus response but a significant difference (p<0.05) was found between the breed groups (Lori: 88.6%, Sanjabi: 58.3%). Among the sheep that received either CIDR or FGA, estrus response was significantly (p<0.05) higher in the Lori (CIDR: 82.2%, FGA: 91.1%) than in the Sanjabi (CIDR: 64.4%, FGA: 52.2%) breed. The lambing and fecundity rates for all groups were 60.2% and 1.2 +/- 0.03, respectively. No significant differences in term of the lambing and fecundity rates were recorded between CIDR and FGA groups and among Lori and Sanjabi breed. The results of this study indicate the source of progestin or sheep breed did not influence the pregnancy and fecundity rates. The sheep breed influences the estrous response rate while the source of progestin did not affect the estrous response.

Comparison of progestin-based protocols to synchronize estrus and ovulation before fixed-time artificial insemination in postpartum beef cows1

This experiment was designed to compare pregnancy rates in postpartum beef cows resulting from fixed-time AI (FTAI) after treatment with 1 of 2 protocols to synchronize estrus and ovulation. Cross-bred, suckled beef cows (n = 650) at 4 locations (n = 210; n = 158; n = 88; and n = 194) were assigned within a location to 1 of 2 protocols within age group by days postpartum and BCS. Cows assigned to the melengestrol acetate (MGA) Select treatment (MGA Select; n = 327) were fed MGA (0.5 mg x head(-1) x d(-1)) for 14 d, GnRH (100 microg of Cystorelin i.m.) was injected on d 26, and prostaglandin F2alpha (PG; 25 mg of Lutalyse i.m.) was injected on d 33. Cows assigned to the CO-Synch + controlled internal drug release (CIDR) protocol (CO-Synch + CIDR; n = 323) were fed a carrier for 14 d, were injected with GnRH and equipped with an EAZI-BREED CIDR insert (1.38 g of progesterone, Pfizer Animal Health, New York, NY) 12 d after carrier removal, and PG (25 mg of Lutalyse i.m.) was injected and the CIDR were removed on d 33. Fixed-time AI was performed at 72 or 66 h after PG for the MGA Select or CO-Synch + CIDR groups, respectively. All cows were injected with GnRH (100 microg of Cystorelin i.m.) at the time of insemination. Blood samples were collected 8 and 1 d before the beginning of MGA or carrier to determine estrous cyclicity status of the cows (estrous cycling vs. anestrus) before treatment [progesterone > or = 0.5 ng/mL (MGA Select, 185/327, 57%; CO-Synch + CIDR, 177/323, 55%); P = 0.65]. There was no difference (P = 0.20) in pregnancy rate to FTAI between treatments (MGA Select, 201/327, 61%; CO-Synch + CIDR, 214/323, 66%). There was also no difference (P = 0.25) between treatments in final pregnancy rate at the end of the breeding period (MGA Select, 305/327, 93%; CO-Synch + CIDR, 308/323, 95%). These data indicate that pregnancy rates to FTAI were comparable after administration of the MGA Select or CO-Synch + CIDR protocols. Both protocols provide opportunities for beef producers to utilize AI and potentially eliminate the need to detect estrus.

Comparison of progestin-based estrus synchronization protocols before fixed-time artificial insemination on pregnancy rate in beef heifers1

The objective of the experiment was to compare pregnancy rates resulting from fixed-time AI after administration of either 1 of 2 controlled internal drug release (CIDR)-based protocols. Heifers at 3 locations (location 1, n = 78; location 2, n = 61; and location 3, n = 78) were assigned to 1 of 2 treatments within reproductive tract scores (1 = immature to 5 = cycling) by age and BW. Heifers assigned to CIDR Select received a CIDR insert (1.38 g of progesterone) from d 0 to 14 followed by GnRH (100 mug, i.m.) 9 d after CIDR removal (d 23) and PGF2alpha (PG, 25 mg, i.m.) 7 d after GnRH treatment (d 30). Heifers assigned to CO-Synch + CIDR were administered GnRH and received a CIDR insert on d 23 and PG and CIDR removal on d 30. Heifers at location 1 were fitted with a HeatWatch estrus detection system transmitter from the time of PG until 24 d after fixed-time AI to allow for continuous estrus detection. Artificial insemination was performed at predetermined fixed times for heifers in both treatments at 72 or 54 h after PG for the CIDR Select and CO-Synch + CIDR groups, respectively. All heifers were administered GnRH at the time of AI. Blood samples were collected 10 d before and immediately before treatment initiation (d 0) to determine pretreatment estrous cyclicity (progesterone > or = 0.5 ng/mL). At location 1, the estrous response during the synchronized period was greater (P = 0.06; 87 vs. 69%, respectively), and the variance for interval to estrus after PG was reduced among CIDR Select- (P < 0.01) compared with CO-Synch + CIDR-treated heifers. Fixed-time AI pregnancy rates were significantly greater (P = 0.02) after the CIDR Select protocol (62%) compared with the CO-Synch + CIDR protocol (47%). In summary, the CIDR Select protocol resulted in a greater and more synchronous estrous response and significantly greater fixed-time AI pregnancy rates compared with the CO-Synch + CIDR protocol.

Evaluation of Progesterone Supplementation in a Prostaglandin F2α-Based Presynchronization Protocol Before Timed Insemination

The objective of the study was to determine the effects of treatment with a controlled internal drug-release (CIDR) insert containing progesterone in a PGF2α-based presynchronization protocol on pregnancy rates at first service in lactating Holstein cows. A total of 1,318 (656 treatment and 662 control) cows from 5 farms were used in the analysis. Cows received a CIDR insert as part of the presynchronization protocol of 2 PGF2α injections given 14 d apart. The CIDR insert was applied during 7 d before the second PGF2α injection, whereas control cows received no CIDR insert. Serum progesterone concentrations were measured in samples collected at 37±3 d in milk (DIM; 7 d after the first PGF2α injection) and at 58±3 DIM, just before initiation of the Ovsynch protocol. According to serum concentrations of progesterone, cows were classified as having either high (≥1 ng/mL) or low (<1 ng/mL) progesterone. The proportion of cows with low progesterone at 37±3 DIM was similar for cows treated later with the CIDR insert (60.7%; n=654) and for control cows (59.2%; n=657). In contrast, use of the CIDR insert resulted in fewer low-progesterone cows (17.4%; n=402) compared with control cows (30.6%; n = 399) at 58±3 DIM. No significant effect of the CIDR insert was detected on overall pregnancy rates. Pregnancy rates, as measured by the percentage of cows pregnant at 37±3 d post timed artificial insemination, for control cows having high or low progesterone at 58±3 DIM were 46.6 and 22.1%, respectively. For the CIDR group, pregnancy rates were 40.4 and 11.4%, respectively, for high- and low-progesterone cows at 58±3 DIM. Overall pregnancy rates were 36.4 and 34.5% for control cows and cows receiving the CIDR insert, respectively. A significant decreasing trend was observed in the proportion of cows having low progesterone as the body condition score increased, at 37±3 and 58±3 DIM. A significant increasing trend in the pregnancy rate was observed as body condition score increased. In conclusion, incorporation of CIDR inserts into a presynchronization protocol reduced the proportion of cows having low progesterone; however, the pregnancy rate did not differ between control cows and those receiving the CIDR insert. Earlier expression of estrus after the second PGF2α injection, and consequently improper timing of initiation of the Ovsynch protocol, could have negatively affected fertility in the CIDR-treated cows.

Ovsynch Plus CIDR Protocol for Timed Embryo Transfer in Suckled Postpartum Japanese Black Beef Cows

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.

Effects of Bovine Somatotropin (bST) Administration Combined with Controlled Internal Drug Release (CIDR) on Embryo Quality and Pregnancy of Hanwoo (Korean Native Beef Cattle) during Commercial Embryo Transfer Program

Effects of recombinant bovine somatotropin (bST) on plasma hormonal concentration, embryo quality, and pregnancy rate were examined during the superovulation and synchronization treatment in donor and recipient cows. Hanwoos (Korean native beef cattle) were treated with controlled internal drug release (CIDR) combined with bST (CIDR+bST) or without bST (CIDR) as donor cows. The embryos recovered from donors were transferred into Holstein recipient heifers treated with bST (CIDR+bST) or without bST (CIDR) for synchronization. The correlation between IGF-I and P4 showed a positive pattern in the CIDR+bST group (r = 0.44, p<0.01), but a negative pattern was shown in the CIDR group (r = -0.59, p<0.02) at day 7 of estrous cycles. Although the number of recovered, transferable, and degenerated embryos was not different, quantities of grade 1 (excellent) embryos in CIDR+bST group were significantly higher than those of the CIDR group (p<0.01). The pregnancy rate was higher in the CIDR+bST recipient group compared to CIDR group (p<0.05), when the embryos were recovered from the donors treated with CIDR. However, the pregnancy was maintained highly in both recipient groups, when the embryos were produced by CIDR+bST treated donors. It can be concluded that bST administration combined with CIDR is an effective method for superovulation and synchronization treatment to stabilize plasma hormonal levels, to obtain excellent quality of embryos, and to get higher pregnancy rate.

Comparison of Estrus Induction and Subsequent Fertility with Two Different Intravaginal Devices in Ewes during the Non-Breeding Season

Two experiments were conducted to compare the effect of estrus induction by controlled internal drug release (CIDR) and intravaginal cream containing 500 mg progesterone (P cream) in ewes during the non-breeding season. In the first experiment, twenty-four ewes were randomly grouped for two treatments with the different intravaginal devices for 12 days: Group A was the CIDR group and Group B was the P cream group. Blood was collected from all treated ewes, and progesterone (P(4)), estradiol 17-beta (E(2)) and luteinizing hormone (LH) concentrations were measured by enzyme immunoassay. In the second experiment, the conception rates from natural mating, estrus-detected AI (inseminated 12 h after estrus detection), or fixed-time AI (inseminated 42 h after removal of an intravaginal device) in 127 ewes treated with CIDR or P cream were compared. In Experiment 1, the rate of estrus induction and the time of estrus onset after device removal were 91.7% and 36.3 +/- 15.7 h in Group A, and 100% and 35.0 +/- 12.6 h in Group B, respectively. There were no significant differences between the devices. The mean plasma P(4) concentration in Group B was significantly (P < 0.01) lower than Group A between day -9 and day -1 (Day 0: the day of device removal). However, no significant differences were found in the mean E(2) concentrations of the two groups after treatment. The mean time of estrus onset in ewes with an observed LH surge and the time of LH surge after treatment were 23.3 +/- 8.7 h and 30.3 +/- 5.0 h for Group A and 27.6 +/- 6.5 and 26.3 +/- 8.0 h for Group B, respectively, and there were no significant differences. However, a significant difference (P < 0.05) was found in the mean time from the time of estrus onset to LH surge between Group A (6.4 +/- 6.7 h) and Group B (-1.3 +/- 4.1 h). In Experiment 2, the conception rates for natural mating, estrus-detected AI, and fixed-time AI were 55.0, 29.4, and 25.0% for Group A and 40.7, 25.0, and 42.1% for Group B, respectively, and there were no significant differences. These results suggest that the effect of induction of estrus and ovulation and the rate of conception after treatment were comparable to CIDR even though the plasma P(4) concentration of the P cream method tended to be low during the insertion period.

Synchronisation of oestrus in goats: the use of different progestagen treatments

The efficiency of medroxyprogesterone acetate (MAP), fluorogestone acetate (FGA) sponges and controlled internal drug release (CIDR) devices for synchronising oestrus in goats was evaluated during the natural breeding season. Ninety does (42 boer goat and 48 indigenous goats) were assigned to Group A ( n=30) 60 mg MAP, Group B ( n=30) 40 mg FGA and Group C ( n=30) CIDR devices. Intravaginal progestagen was administered for a 16-day period. Upon progestagen withdrawal, does received 300 IU PMSG intramuscularly. Cervical inseminations with fresh diluted semen at a fixed time (48 and 60 h) followed progestagen withdrawal. The three progestagen treatments did not show significant differences in oestrous response (97%) and duration (33.3±13.4) of the induced oestrous period. Time to the onset of oestrus significantly advanced in the CIDR (27.2±0.4 h) group, when compared to FGA the (30.9±0.4 h) and MAP (32.2±0.5 h) groups. The mean serum progesterone concentrations in the CIDR group were higher ( P<0.05) between days 4 and 16 of progestagen treatment, compared to the MAP and FGA groups. No significant difference was observed with respect to pregnancy rate 40 days after AI (52, 60 and 47% for CIDR, MAP and FGA groups, respectively). Results indicate that the use of MAP, FGA and CIDR intravaginal progestagen treatments are equally efficient in synchronising oestrus in goats.

Estrus synchronization and artificial insemination of hair sheep ewes in the tropics

Hair sheep ewes (St. Croix White and Barbados Blackbelly) were used to evaluate 3 methods of estrus synchronization for use with transcervical artificial insemination (TAI). To synchronize estrus, ewes (n = 18) were treated with PGF2α (15 mg, im) 10 d apart, with controlled internal drug release (CIDR) devices containing 300 mg progesterone for 12 d (n = 18), or with intravaginal sponges containing 500 mg progesterone for 12 d (n = 18). On the day of the second PGF2α injection or at CIDR or sponge removal, sterile rams were placed with the ewes. Jugular blood samples were collected from the ewes at 6-h intervals until the time of ovulation, and daily for 16 d after estrus (Day 0). Plasma was harvested and stored at −20°C until LH, and progesterone concentrations were determined by RIA. There was no difference (P > 0.10) in time to estrus among the CIDR-, PGF2α- or sponge-treated ewes. All of the ewes in the CIDR group and 94.4% of the sponge treated ewes exhibited estrus by 36 h after ram introduction, while only 72.2% of PGF2α-treated ewes showed signs of estrus by this time (P < 0.06). The time from ram introduction to ovulation was not different (P > 0.10) among the CIDR-, PGF2α- or sponge-treated ewes. The time to the preovulatory LH surge was similar (P > 0.10) among CIDR, PGF2α and sponge treated ewes. Progesterone levels through Day 16 after the synchronized estrus were not different (P > 0.10) among treatment groups. Hair sheep ewes (n = 23) were synchronized using PGF2α and bred by TAI using frozenthawed semen 48 h after the second injection. The conception rate to TAI was 2 23 (8.7%) and produced 3 ram lambs. In a subsequent trial, 17 ewes were synchronized with CIDR devices and bred by TAI using frozen-thawed semen 48 h after CIDR removal, resulting in a conception rate of 52.9 % ( 9 17 ). It is possible to synchronize estrus in hair sheep using either CIDRs, sponges or PGF2α. Even though there were no significant differences in the timing of ovulation or the LH surge among the treatment groups, a higher conception rate was achieved in ewes synchronized with CIDR devices during the second trial. This may reflect an increase in the skill level of the TAI technician.