Controlled Internal Drug Release Dispenser Research Articles

β-carotene Supplementation Increases Progesterone Concentration and Glutathione Peroxidase Activity Following Alternative Progesterone Primed Oestrous Synchronization Protocol in Goats

The present study evaluated the effect of β-carotene supplementation and oestrous synchronization protocol on ovarian activity and fertility of Saanen does during the breeding season. The supplemented group received 100 mg β-carotene during the breeding and all does were synchronised with Controlled Internal Drug Release dispenser (CIDR) and injected with cloprostenol at CIDR withdrawal. One group of does were injected with 300 IU of eCG, while in another group bucks wearing aprons were introduced at CIDR withdrawal. Does were artificially inseminated twice (48 and 60 h) with fresh undiluted semen. The onset and duration of oestrus, progesterone, oestrdiol-17β and glutathione peroxidase activity, oestrous response and conception rate were analysed. Synchronization protocol did not affect response to oestrus, onset and duration of oestrus and oestradiol-17β concentration. The male presence group had significantly higher conception rate (97%) than the eCG (72%) group. β-carotene supplemented group had higher progesterone concentration and glutathione peroxidase activity. Supplemental β-carotene during the breeding period therefore, could play an important role on establishment of pregnancy due to high progesterone concentration and glutathione peroxidase activity. Inclusion of male effect in progesterone based oestrous synchronization protocol improves conception rate. Therefore, male effect can be used as an alternative to equine chorionic gonadotropin in progesterone based oestrous synchronization protocols especially, where drugs for oestrous synchronization are not affordable.

Oestrous synchronisation and pregnancy rate following artificial insemination (AI) in South African indigenous goats

The study evaluated the effect of duration of progestagen treatment and breed on response to oestrous synchronisation and pregnancy rate following AI in 47 Boer and 27 unimproved indigenous goats. Each breed was subdivided into two groups, based on the duration of progestagen treatment. In the long-term progestagen treatment, controlled internal drug release dispensers (CIDRs) were inserted for 16 days, while in the short-term progestagen treatment, CIDRs were inserted for 9 days. Oestrous detection was performed for a period of 72 h, starting at CIDRs withdrawal. AI was performed 48 h following CIDRs removal with raw or frozen/thawed semen. Pregnancy diagnosis was performed at day 35 following AI. Boer goat exhibited a significantly (p <0.05) higher oestrous response (100%) than unimproved indigenous goats (88.9%). Breed had no effect on the onset of oestrus. Boer goat does recorded a longer duration of the induced oestrous period, compared to the unimproved indigenous goats. No significant difference was observed between short or long-term progestagen, with respect to the oestrous response, onset and duration of the induced oestrous period. The pregnancy rate was not affected by breed and semen cryopreservation. However, long-term progestagen treatment drastically reduced pregnancy rate. In conclusion, breed had an effect on oestrous response and the duration of induced oestrous period. The interaction of breed and duration of progestagen treatment had no effect on response to oestrus and onset of oestrus. The pregnancy rates of the current study were generally low and were affected by the duration of progestagen treatment.

Effect of Low Dose of hCG on Induction of Fertile Estrus in Shiba Goats Pretreated Intravaginally with Progesterone during the Early Postpartum Nursing Period.

The present study was conducted to determine the effect of a low dose of human chorionic gonadotropin (hCG) on the induction of fertile estrus in Shiba goats pretreated intravaginally with progesterone during the early postpartum period. Nursing Shiba goats (n=13) around 3 weeks after the parturition were pretreated with a controlled internal drug release dispenser (CIDR) containing 0.3 g of progesterone for 7 day, and 60 μg of cloprostenol 24 hr before CIDR removal. Goats in Group I (n=6) received subcutaneous injections of a low dose of hCG (1 IU/kg) after the removal of CIDR at 12-h intervals until the occurrence of estrus. Goats in Group II (n=7, control) received subcutaneous injections of saline instead of hCG. The rate of estrus induction in Group I (83.3%) tended to be higher than that in Group II (42.9%), although the difference was not significant (P=0.14). Time from the removal of CIDR to the beginning of estrus in Group I was significantly shorter than that in Group II (P<0.05). A prominent peak of estradiol-17 β concentration in plasma was observed with a maximum value at 30 h after the removal of CIDR in Group I, while two relatively small rises were detected with a maximum value at 48 h in Group II. The pregnancy rate in Group I (83.3%) was significantly higher (P<0.05) than in Group II (28.6%). These results suggest that the injections of low dose hCG after the treatment with CIDR promote follicular maturation and fertile estrus induction in the goats during the early postpartum nursing period.

Effect of Different hCG Treatments on Fertility of Estrus-Induced and Artificially Inseminated Ewes During the Non-Breeding Season

The present study was conducted to determine the effect of two human chorionic gonadotropin (hCG) treatments on the fertility of ewes which were estrus-induced and artificially inseminated during the non-breeding season. Suffolk (SF: n=68) and South-Down (SD: n=20) ewes were pretreated with a controlled internal drug release dispenser (CIDR) for 12 days and 500 IU equine chorionic gonadotropin 1 day before CIDR removal. Each breed of ewes were divided into 3 groups: Group I (n=31), an intramuscular injection of 100 IU hCG was given on Days 3, 4 and 5 after artificial insemination (AI) (Day 0=the day of AI); Group II (n=29), an injection of 300 IU hCG was given on Day 4; and Group III (n=28, Control), an injection of 0.6% saline was given on Day 4. Plasma progesterone (P4) concentrations were measured by enzyme-immunoassay in all ewes in the three groups at the time of insemination (Day 0), and Days 4, 8, 12, 16, and 20 after AI. On Day 8, the mean P4 concentrations in ewes treated with hCG (Groups I and II) were significantly higher (P<0.01) than in the control ewes (Group III). In Group II, the mean P4 values on Days 14 and 18 were also higher (P<0.05) than those in the control ewes. Pregnancy (Days 20 and 58) and lambing rates were not significantly different among the three groups (37.9%, 55.2% and 54.2% for lambing rates). Prolificacy was also not significantly different among the three groups (1.36, 1.75 and 1.62). These results indicate that the present hCG treatment did not enhance fertility of the inseminated ewes, although the treatment stimulates corpus luteum and increased P4 concentrations.

Evaluation of laparoscopic intrauterine insemination in ewes

This study was conducted at the Nimbkar Agricultural Research Institute in Maharashtra, India to evaluate the feasibility of using the technique of laparoscopic intrauterine insemination in ewes under field conditions for the first time in India. Two groups of multiparous Patanwadi ewes were synchronized into oestrus, one group with vaginal sponges and the other with Controlled Internal Drug Release dispensers (CIDRs). Both groups were injected with 500 IU pregnant mare serum gonadotrophin (PMSG) and were inseminated with the laparoscopic intrauterine technique at 56–58 h after sponge/CIDR removal. The first group of 30 ewes was inseminated in January 1992 with fresh, diluted Awassi ram semen which was not pooled. The second group of 25 ewes was inseminated in June 1992 with fresh, undiluted Awassi ram semen which was not pooled. The conception rates were 77% and 72%, respectively and the lambing rates (percentage of ewes lambing) were 77% and 60% for the two groups. In addition, 35 Patanwadi ewes, some of which were the same as those in the first two groups, were cervically inseminated on natural oestrus with fresh, undiluted Awassi ram semen (not pooled) between October 1992 and October 1993. Similarly, 18 Patanwadi ewes on natural oestrus were naturally mated with Awassi rams during the same period. The conception rates were 69% and 83%, respectively and the lambing rates were 57% and 78% for the cervically inseminated and naturally mated ewes. The technique of laparoscopic intrauterine insemination in ewes was thus used successfully under primitive conditions.

CIDR: A new progesterone-releasing intravaginal device for induction of estrus and cycle control in sheep and goats

The controlled internal drug release dispenser (CIDR) is an intravaginal device constructed of a progesterone-impregnated medical silicone elastomer molded over a nylon core. The CIDR-G is suitable for treatment of parous ewes, lambs and goats. Plasma progesterone levels increase rapidly after insertion of CIDR, reach highest concentrations on Day 3 and then gradually decrease. In an on-farm trial conducted during the breeding season, CIDR were used to synchronize estrus. The bulk of ewes lambed within 6 days of each other. A second group of ewes lambed 16 days after the first in which 20% of ewes lambed. Sponges and CIDR were compared for out-of-season breeding using pregnant mares serum gonadotropin (PMSG). Both types of pessaries were effective when used with PMSG. Percentages of ewes bred, ewes lambing and lambs born were similar for sponge and CIDR-treated ewes. Out-of-season breeding also was stimulated without PMSG. For this purpose, CIDR were applied in conjunction with the ram effect. A month before the onset of the normal breeding period, ewes were treated with CIDR and then exposed to rams. Estrus, conception and lambing were advanced in ewes that had received CIDR compared with those that had not. In a subsequent experiment, breeding was advanced, and after lambing and lactation, ewes were retreated with CIDR/ram effect in late winter/early spring. Most ewes (94%) lambed the following summer. In goats, CIDR have been substituted successfully for sponges for estrous synchronization, superovulation, artificial insemination and embryo transfer. The CIDR-G provides a convenient means to deliver exogenous progesterone to sheep and goats and offers an alternative to the progestogen sponge for reproductive management.

Time of ovulation in the South Australian Merino ewe following synchronization of estrus. 1. Variation within and between flocks

Observations were made by repeated laparoscopy to determine the time of ovulation in seven flocks of South Australian Merino ewes treated with pregnant mare serum gonadotropin (PMSG, 400 IU per ewe) and an intravaginal pessary containing 60 mg medroxy-progesterone acetate (MAP). Ovulation most often commenced within 57 h of pessary removal and was completed in all flocks within 81 h. There was, however, significant variation in the time of onset of ovulation; it did not commence until 69 h in one of three observations of Flock 1 and in two of three observations of Flock 2. On the other hand, in a flock of two-year-old nulliparous ewes (Flock 7), ovulation commenced significantly (P < 0.001) earlier than in most observations of other flocks, with 18 39 ewes ovulating within 57 h of pessary removal. The effect of the progestagen (MAP vs flugestone acetate) and the gonadotropin preparation (Pregnecol vs Folligon) on the time of ovulation were observed in separate studies. The characteristic time of ovulation was not influenced in either comparison. However, ovulation occurred significantly (P < 0.001) earlier in ewes treated with progesterone released from a controlled internal drug release dispenser (CIDR). The implications of these findings to artificial insemination and embryo transfer are discussed.

Comparison of progesterone sponges, cronolone sponges and controlled internal drug release dispensers on fertility in anestrous ewes

Three farm trials involving 581 mature ewes were conducted during April and May of 1984, 1985 and 1986. All ewes had lambed and lactated prior to treatment. In the first trial, polyurethane sponges containing 400 mg progesterone or 30 mg Cronolone were compared. On each of six farms, ewes were assigned randomly in approximately equal numbers to treatment groups. Sponges were left in place for 14 days and upon withdrawal ewes were injected with 750 IU pregnant mare serum gonadotropin (PMSG). Another PMSG injection was given 16 days later. Rams ( 1 10 ewes) were joined 2 days later. Responses to treatments were similar ( P > 0.05). Of ewes treated with progesterone and Cronolone sponges, respectively, 86 and 87% were bred, 56 and 60% lambed and 83 and 105% lambs were born. The second trial was conducted like the first except that 366 mg progesterone type S controlled internal drug release dispensers (CIDR-S) and Cronolone sponges were compared in ewes on each of 10 farms. Similar results were obtained with CIDR-S and sponges in numbers of ewes bred (92 and 93%), ewes lambing (64 and 73%) and lambs born (100 and 108%). In both trials significant differences in response rates were noted among farms. A third trial was conducted to determine whether CIDR-S without PMSG would induce fertility in anestrous Suffolk ewes. One of 25 animals was bred following dispenser removal and no ewes subsequently lambed. In conclusion, natural progesterone delivered via intravaginal sponges or CIDR-S can replace Cronolone for progestogenic priming of anestrous ewes.

Evaluation of progesterone controlled internal drug release dispensers for synchronization of estrus in sheep

Three experiments were conducted to evaluate 366 mg progesterone, type S, controlled internal drug release dispensers (CIDR-S) for estrous synchronization. In Experiment 1, synchronization of estrus was investigated in early fall. Of 129 ewes treated for 12 days, 117 (91%) were bred within 5 days of dispenser removal. A total of 118 (91%) ewes lambed with 74% of lambings occurring within 6 days of each other. In Experiment 2, duration of progesterone release from CIDR-S was examined over a 45-day period. In ovariectomized ewes, plasma progesterone levels were 2.8 ng/ml 3 days after insertion and then decreased gradually to 0.3 ng/ml by day 30. In cycling ewes, Day 3 levels were 4.5 ng/ml due to contribution of luteal progesterone. Exogenous progesterone blocked estrus and ovulation for 27 to 31 days, after which ovulation occurred without estrus. Estrus with ovulation occurred by Day 38 to 45. In Experiment 3, cycling ewes were treated for 0, 4 or 12 days and progesterone residue in adipose, liver, kidney and muscle tissues was measured. Residues differed ( P < 0.05) among treatment groups and tissue types with no interaction. Tissue progesterone levels of ewes treated for 4 days were greater than those in ewes treated for 0 and 12 days. Adipose tissue contained over 10 times as much progesterone as other tissues. Progesterone residues were related ( r = 0.5, P < 0.05) to circulating progesterone levels at time of death but with neither total nor peak levels reached during the treatment period. CIDR-S had a 92% retention rate and provided a simple and effective delivery of natural progesterone.

Effects of immunisation with polyandroalbumin (Fecundin), pasture allowance, post-mating shearing, and method of synchronisation on reproductive performance of Romney and Marshall Romney ewes

Abstract Mature Marshall Romney (MR) and control Romney (CR) ewes were used in a factorial experiment to determine the effects of immunisation with polyandroalbumin (Fecundin; Glaxo N.Z. Ltd) on reproductive performance of ewes on low or moderate pre-joining pasture allowances (0.8 and 3.0 kg green DM per ewe per day respectively). Comparisons were also made of the effects of shearing 10 days post-mating on reproductive performance and the effects of using CIDRs (controlled internal drug release dispensers) compared wlth sponges for the synchronisation of oestrus. Age and strain of ewes had no effect on the increase in ovulation rate or multiple births following immunisation. Immunisation with Fecundin increased ovulation rate by the same amount for ewes on the two pasture allowances (34–35%), and there was a 16–19% increase in ewes lambing multiples. The increase in pasture allowance from 0.8 to 3.0 kg green DM per ewe per day was associated with a 20% increase in ovulation rate and an 18% increase in ewes lambing multiples. Sheanng post-mating had no effect on the reproductive performance of the ewes. Ewes treated with the CIDRs had an earlier onset of oestrus than ewes treated with sponges. Over the first 10 days, fewer of the ewes treated with CIDRs were mated (87 v. 94%) as a result of a higher loss rate of the CIDRs (6.3%) compared with sponges (0.8%).

Synchronization of oestrus in sheep: The use of controlled internal drug release (CIDR) dispensers

The use of the CIDR (controlled internal drug release) dispenser as a progestagen-synchronizing agent was evaluated in 37 Karakul ewes during the breeding season, using the intravaginal progestagen sponge as a control (30 ewes). Although there was no significant differences in oestrous response, following intravaginal insertion for 14days, between these two progestagen devices, the time from device withdrawal to the onset of the induced oestrous period (31,2 vs 62,5 h) and the duration of the induced oestrous period (32,7 vs 47,4 h) was significantly (P<0,01) shorter in the CIDR dispenser group. The mean time from device withdrawal to the serum preovulatory LH peak and the interval from the onset of oestrus to the pre-ovulatory LH peak was significantly (P<O,Ol) earlier in the CIDR dispenser group (28,0 vs 78,0 hand 5,3 vs 17,3 h respectively). No significant difference in the serum progesterone concentrations was noted between the two groups. No significant difference in reproductive performance was obtained with conception, lambing rates and fecundities of 72,2 vs 79,3%; 75,0 vs 89% and 103,8 vs 113,0% for the dispenser and sponge treatment groups respectively. Results confirm the potential of the CIDR dispenser as an efficient synchronizing agent and the more concentrated synchrony obtained makes it ideal for fixed-time insemination.

A controlled internal drug-release dispenser containing progesterone for control of the estrous cycle of ewes

Experiments were conducted to evaluate a controlled internal drug-release (CIDR) dispenser containing progesterone to control the estrous cycle of ewes. After insertion of CIDR dispensers into the vaginae of ovariectomized ewes (Experiment 1; n = 11), the mean plasma progesterone rose from 0.74 ± 0.2 ng/ml to a peak of 5.5 ± 1.0 ng/ml within 2 h and then declined to 3.0 ± 0.5 ng/ml by 48 h. This was followed by a more gradual decline to 1.7 ± 0.3 ng/ml at the time of removal 12 or 14 d later. Following removal, the levels declined to baseline within 4 h. In Experiment 2, a 12- or 14-d treatment with CIDR dispensers was initiated in ewes 2, 9 and 16 d after synchronization of the estrous cycle with fluorogestone acetate (FGA)-impregnated intravaginal sponges. An intramuscular (i.m.) injection of 500 IU pregnant mare serum gonadotropin (PMSG) was given at the time of removal of the FGA sponge or CIDR dispenser. Based on plasma progesterone profiles, CIDR dispensers inserted 9 or 16 d after FGA sponge removal delayed the onset of a new estrous cycle until they were withdrawn. Following withdrawal, ovulation was effectively synchronized in all treatment groups and accompanied by development of functionally active corpora lutea with a normal lifespan. In Experiment 3, comparison of the mating response of ewes after treatment with CIDR dispensers (n = 192) or FGA sponges (n = 194) showed that 92% and 91% of the treated ewes, respectively, were marked by the ram within 72 h. Fertility and litter size of ewes bred at the synchronized and followup estrus were similar for both treatments. These results indicate that treatment of ewes with CIDR dispensers containing progesterone maintains plasma levels of progesterone within the range found during the normal estrous cycle. The CIDR dispenser is effective in synchronizing the estrous cycle of adult ewes and offers a promising alternative to the FGA-impregnated intravaginal sponge.

Plasma progesterone levels in ewes treated with progesterone-controlled internal drug-release dispensers, implants and sponges

Replicate experiments were conducted using ovariectomized ewes to evaluate four progesterone-releasing devices. Treatments were: (1) controlled internal drug-release (CIDR) dispensers containing 12% (w/w) progesterone, (2) CIDR dispensers containing 9% progesterone, (3) solid silastic implants containing 0.9 g progesterone, and (4) polyurethane sponges containing 0.4 g progesterone. Progesterone CIDR dispensers had an outer surface of silicone elastomer impregnated with progesterone and weighed 5.2 g. Implants and pessaries were inserted 9 days after ovariectomy and left in place for 13 days (Exp. 1). Nine days later, ewes were rerandomized and progesterone treatments reimposed for another 13 days (Exp. 2). Blood samples were taken daily beginning 1 day pretreatment. Progesterone levels were similar in replicate experiments but differed significantly between treatments and days. Pretreatment progesterone levels were generally <0.2 ng/ml. Twelve and 9% CIDR dispensers produced similar progesterone levels, which averaged (± SEM) 1.9 ± 0.1 and 1.8 ± 0.1 ng/ml, respectively. Progesterone concentrations increased within 24 h to near maximum levels, reached highest levels on day 4 (2.5 ± 0.6 and 2.2 ± 0.1 ng/ml, respectively), and then declined gradually to day 13 values of 1.6 ± 0.2 and 1.4 ± 0.2 ng/ml, respectively. Mean progesterone levels were lower ( P<0.001) in ewes with implants (0.8 ± 0.1 ng/ml) and sponges (1.0 ± 0.1 ng/ml). Dispensers, implants and sponges produced similar peak progesterone levels [treatment: (1) 3.4 ± 0.4, (2) 2.8 ± 0.1, (3) 2.9 ± 0.5, (4) 2.3 ± 0.4 ng/ml]. Twelve and 9% CIDR dispensers produced the highest and most sustained plasma progesterone levels over the 13-day period.