Progesterone Sponges Research Articles

Effect of fasting on luteal function, leptin and steroids concentration during oestrous cycle of the goat in natural photo-status

The effect of fasting during oestrous cycle on the occurrence of oestrous and concentration of leptin and steroid hormones was investigated in goats. Sixteen Ardi goats of 10–12 month of age were split into two groups (control and fasting). Oestrous was synchronized with intravaginal progesterone sponges and detected 24 h after sponge removal. Blood samples were collected at the days 5, 10, 15 of each cycle. Fasting of mature goats twice for 4 days starting on day 10 of two successive oestrous cycles inhibited oestrous behaviour and resulted in reduced concentration of leptin, progesterone and testosterone with different timing. Day 5 of the second cycle showed significant decrease in the plasma level of leptin (1.6 ± 0.15 ng/ml) and progesterone (1.6 ± 0.1 ng/ml) as compared to control group (3.2 ± 0.15 ng/ml and 4.1 ± 0.2 ng/ml, respectively). Testosterone started to decrease from day 10 of the second cycle (35.0 ± 12.0 pg/ml) as compared to control group (65.0 ± 15.0 pg/ml); the decrease in this hormone was significant in day 15 of the second cycle (65.0 ± 16.0 pg/ml) as compared to the control (320.0 ± 50.0 pg/ml). These data suggest that fasting-induced inadequate corpus luteum function, hence, lowering progesterone plasma level may partly be more leptin-dependent than the following decrease in plasma level of testosterone.

Proteinase-activated receptors in ovine cervical function

In sheep, inflammation not only functions in cervical dilation at parturition, but also plays an important part in the non-pregnant ewe cervix, as demonstrated by the high level of expression of interleukin (IL)-8 at oestrus. Ewes artificially induced to ovulate have significantly lower levels of IL-8 gene expression at oestrus compared with natural oestrus, indicating an inhibition of inflammation and function, offering an explanation for the low rates of conception in vaginally inseminated synchronised ewes. To identify potential pro-inflammatory agents to combat the anti-inflammatory effects of hormonal synchronisation of oestrus, we have investigated the role of proteinase-activated receptor (PAR)-1 and PAR-2. To localise and measure the level of expression of these receptors, ovine-specific probes were derived for PAR-1 and PAR-2 and used for quantitative in situ hybridisation in the ovine cervix. Both PAR-1 and PAR-2 were expressed in the luminal epithelium of the cervix throughout the oestrous cycle, with expression being highest at oestrus. The gene expression of PAR-2 at oestrus was approximately 30% higher than that of PAR-1. Artificial synchronisation of oestrus by either an intravaginal progesterone sponge or prostaglandin F2+/- injections did not inhibit PAR-1 or PAR-2 expression at oestrus; rather, in the case of PAR-2, progesterone synchronisation increased it. Both synchronising procedures increased the expression of PAR-1 and PAR-2 during the luteal phase of the cycle. Therefore, agonists of PAR-1 and PAR-2 may be potentially useful pro-inflammatory agents countering the inhibition of inflammation by hormonal synchronisation.

Temperament and sexual experience affect female sexual behaviour in sheep

Our aim was to study the effect of temperament and sexual experience on female sexual behaviour. We used ewes from a flock that had been genetically selected for ‘calm’ or ‘nervous’ temperament, in which oestrus was synchronized by a 14-day treatment with intravaginal progesterone sponge. Using standardized behavioural tests to measure the proceptivity (initiative in establishing interaction with the male and active sexual solicitation) and the receptivity (acceptance of the male nudges and adoption of mating posture), we compared the sexual behaviour of females from four groups that differed in their temperament (calm or nervous) and their sexual experience (2–4 years experienced or 1–2 years naive). Compared to nervous ewes, calm ewes were significantly more proceptive 32 h after sponge withdrawal ( P<0.05) and more receptive 48 and 72 h after sponge withdrawal ( P<0.05). Experienced ewes, both calm and nervous, were more receptive than inexperienced ewes 64 h after sponge withdrawal ( P<0.05). We conclude that temperament and lack of sexual experience and/or age can affect female sexual behaviour in sheep and that these two factors should be taken into consideration for flock management.

Reproductive responses following royal jelly treatment administered orally or intramuscularly into progesterone-treated Awassi ewes

An experiment was conducted to determine whether natural royal jelly (RJ) paste administered orally or intramuscularly (i.m.) in conjunction with exogenous progesterone is associated with improved reproductive responses in ewes. Thirty 3–6-year-old Awassi ewes were randomly allocated into three (RJ-capsule, RJC; RJ-injection, RJI and control, CON) groups of 10 ewes each. All ewes were treated with intravaginal progesterone sponges for 12 days. Ewes in the RJC and RJI were administered orally or i.m. with a total of 3 g of RJ given in 12 equal doses of 250 mg per ewe per day starting at the time of sponge insertion. At the time of sponge withdrawal (day 0, 0 h), ewes were exposed to three rams and checked for breeding marks at 6-h intervals for 3 days. Blood samples were collected from all ewes for analysis of progesterone concentrations. Pretreatment progesterone levels were <0.5 ng ml −1 in 16/30 and >1.3 ng ml −1 in the remaining ewes indicating luteal function and cyclicity. Similar reproductive responses and progesterone levels occurred in ewes of the RJC and RJI; therefore, data of the two groups were pooled. Following sponge insertion, progesterone levels increased rapidly and reached maximum values of 5.8±0.2 ng ml −1 within 2 days among ewes of the three groups, and then declined gradually to day 0 values of 1.6±0.1 and 1.9±0.1 ng ml −1 for the RJ-treated and CON ewes, respectively. The rate of progesterone decline was greater ( P<0.001) in RJ-treated than in CON. Mean progesterone levels during the 12-day period were lower ( P<0.001) in RJ-treated than in CON (2.8±0.2 ng ml −1 versus 3.3±0.2 ng ml −1). Treatment with RJ resulted in greater ( P<0.05) incidence of oestrus and shorter ( P<0.05) intervals to onset of oestrus than CON. Based upon progesterone levels, ovulation occurred following day 0 in all ewes. Progesterone increased on day 3 in RJ-treated and on day 4 in CON ewes. Progesterone remained elevated through day 18 in 8/20 RJ-treated and 1/10 CON ewes ( P=0.09). All pregnant ewes exhibited oestrus 14 h earlier ( P<0.02), ovulated approximately 1 day earlier and had higher ( P<0.001) luteal phase progesterone levels than non-pregnant ewes. Non-pregnant had higher ( P<0.04) body weights than pregnant ewes. In conclusion, results demonstrate that both RJ treatments in conjunction with exogenous progesterone were equally capable of improving oestrus response and pregnancy rate.

Reproductive Responses of Awassi Ewes Treated with either Naturally Occurring Progesterone or Synthetic Progestagen

The objective was to identify the appropriate form of progesterone, which exhibits compact reproductive responses in Awassi ewes during mid to late seasonal anestrous period. Forty-eight Awassi ewes were randomly allocated into four groups to be treated with 60 mg medroxyprogesterone acetate (MAP), 30 mg fluorogestone acetate (FGA), 40 mg FGA, or 600 mg progesterone sponges. After a 12 day period, sponges were removed and ewes were administered i.m. with 600 IU PMSG (d 0, 0 h). Five harnessed Awassi rams were turned-in with the ewes to detect heat. Ewes were checked for breeding marks at 6 h intervals for 5 days. Blood samples were collected from all ewes for analysis of progesterone concentrations. Pretreatment (d -13 and -12) progesterone concentrations were ≤0.2 ng/mL among all ewes and were indicative of seasonal anestrous period. On d 0, progesterone concentrations were elevated to 1.4±0.1 ng/mL in ewes received progesterone sponges only and were higher (p 0.1) among all ewes. Incidence of estrus was similar (p>0.1) among the four groups and occurred in 75% (9/12), 82% (9/11), 67% (8/12) and 58% (7/12) of the ewes receiving MAP, 30 mg FGA, 40 mg FGA and progesterone sponges, respectively. Estrous responses occurred 14.7, 20 and 13.6 h earlier in progesterone-sponge-treated ewes than those of MAP- (p 0.1) among ewes of the four treatment groups. Ewes that returned to estrus 16 to 20 days following d 0 were 5/12, 5/11, 6/12 and 4/12 ewes treated with MAP, 30 mg FGA, 40 mg FGA and progesterone sponges, respectively, and all lambed 169 days later. Overall lambing rates were 75% (9/12), 82% (9/11), 75% (9/12) and 58% (7/12) ewes treated with MAP, 30 mg FGA, 40 mg FGA and progesterone sponges, respectively. Results demonstrate that applications of MAP, 30 mg FGA, 40 mg FGA and progesterone sponges Awassi ewes were equally effective in induction of estrus and tended to favor both types of FGA and MAP in overall lambing rates over progesterone sponges during the seasonal anestrous period. (Asian-Aust. J. Anim. Sci. 2002. Vol 15, No. 9 : 1257-1262)

Effect of two doses of progesterone on estrus response and fertility in acycling crossbred Bharat Merino ewes in a semi-arid tropical environment

The efficacy of two doses of progesterone (P4), i.e. 350 and 300 mg was evaluated in acycling crossbred ewes (50) during the autumn breeding season. Ewes were treated with intravaginal progesterone sponges with either 350 mg or 300 mg for 12 days. At standing estrus, ewes were hand mated (three cycles). Progesterone (350 mg) gave a better ( P<0.05) estrus response (75%), compared to 300 mg dose (42%). Ewes treated with 350 mg P4 also showed better ( P<0.05) synchronization response (93%) than those treated with 300 mg (56%) at 72 h after sponge removal. Lower doses of progesterone (300 mg) significantly delayed ( P<0.01) the onset of estrus. However, dose had no significant influence( P>0.05) on estrus length, conception rate and the proportion of ewes lambing at term. This study indicates that dose of progesterone may have an effect on estrus exhibition and response time without altering the conception rate and lambing in acycling crossbred Bharat Merino ewes during the major breeding season in a semi-arid tropical environment.

A comparison of the effects of progesterone sponges and ear implants, pgf2alpha, and their combination on efficacy of estrus synchronization and fertility of mashona goat does

Efficacy of estrus synchronization and fertility after synchronization of 60 multiparous Mashona goat does using intravaginal progesterone (P 4) sponges (Group 1), norgestomet ear implants (Group 2), cloprostenol (Group 3), or a combination of P 4 sponges and cloprostenol (Group 4) was compared with untreated does (Group 5). At the end of treatments, all does were mated to intact fertile bucks for 21 d. The number of does bred within 11 to 96 h was significantly higher (P < 0.05) in the treated groups than the untreated control, with rates of 80, 80, 64, 67 and 30% for Groups 1 to 5, respectively. There were no differences (P > 0.05) among treated does. Kidding rates ranged from 64 to 83% but were not different (P > 0.05) between groups. Prolificacy and overall fecundity were similar (P > 0.05) among the groups. The results indicate that all 4 treatment methods were effective in synchronizing estrus and that none of the methods affected overall fertility of the does.

The effect of dietary molybdenum and sulphate on the oestrus cycle and ovulation in ewes after manipulation with exogenous progesterone alone or in combination with FSH and LH

Sixteen adult South African Mutton Merino ewes ( Ovis aries) were divided in two groups. The diet of the experimental animals was supplemented with molybdenum (Mo: 38 mg/kg feed) and sulphur (S: 0.34%) to induce a secondary copper deficiency. Two trials were conducted with four control and four experimental animals in each trial. After synchronisation with progesterone sponges during Trial 1, all the control ewes showed behavioural oestrus with subsequent corresponding ovarian and hormonal reactions. Only one of the experimental ewes showed signs of oestrus. During Trial 2, the ewes were superovulated using progesterone sponges and e-FSH. All control ewes showed signs of behavioural oestrus as opposed to 50% of the experimental animals. The ovarian weight (g) (3.52 ± 0.89 versus 1.50 ± 0.57) and number of follicles (7.52 ± 7.35 versus 14.5 ± 4.93) were reduced ( p < 0.05) compared to the control animals. According to the hormonal profiles the progesterone, FSH and LH concentrations were lower ( p < 0.05) in ewes suffering from a Cu deficiency compared to control animals. It is suggested that a Mo and S induced Cu deficiency inhibits GnRH release or the production of FSH and/or LH to such an extent that cyclicity in the ewe is suppressed.

Foetal cross-protection experiments between type 1 and type 2 bovine viral diarrhoea virus in pregnant ewes

A flock of 82 non-pregnant ewes was split into three immunisation groups and given an intranasal dose of either cell culture medium, or a type 1 or a type 2 bovine viral diarrhoea virus (BVDV-1 or BVDV-2). Two months later the flock was reconstituted and after a further three weeks, the ewes were bred to pestivirus negative rams after synchronisation of oestrus using progesterone sponges. Fifty-five ewes were segregated into three challenge groups, each of which comprised ewes from different immunisation groups. At 7 weeks gestation, one challenge group was given an intranasal dose of cell culture medium, whilst the other two were given intranasal doses of either BVDV-1 or BVDV-2, using the same inocula as for the immunisations. Three weeks later, the ewes were killed and their foetuses tested for the presence of BVDV-1 and BVDV-2. The results showed that immunisation of six ewes without subsequent challenge did not lead to infection of any of their 11 foetuses. Challenge with BVDV-1 or BVDV-2 in the absence of immunisation lead to 15 out of 15 or 11 out of 14 foetuses becoming infected, respectively. Immunisation with the homologous virus to that used for challenge resulted in complete protection of 32 foetuses from 15 ewes. Heterologous protection was one way. All 12 foetuses from ewes immunised with BVDV-1 were protected from challenge with BVDV-2, whereas 18 foetuses from ewes immunised with BVDV-2 were all infected after challenge with BVDV-1. This provides evidence that a recent exposure to infection with one pestivirus does not necessarily induce foetal protection against another. The one-way result suggests that factors other than antigenic differences are involved in cross-protection.

Comparison of Fertility of Estrous Synchronized Ewes with Four Different Intravaginal Devices during the Breeding Season.

Comparative studies of four different intravaginal devices containing progesterone or synthetic progestogens on estrous incidence, LH surge and fertility of synchronized ewes by an intrauterine insemination with frozen semen by laparoscopy were conducted during the breeding season. A total of 161 Suffolk or Suffolk-crossed ewes at two sheep farms (Farms A and B) were used. In Farm A, the mean times of estrous onset after the removal of four intravaginal devices were 27.3, 31.2, 21.8 and 22.8 h for MAP, FGA, CIDR and P sponge (self-made progesterone sponge), respectively. The progesterone-impregnated intravaginal devices (CIDR and P sponge) induced estrus significantly earlier (P 2.0 ng/ml) on Day 21 (Farm B) and lambing rates (Farms A and B) of ewes inseminated once on a fixed-time basis between 44 and 52 h after removal of intravaginal devices were not significantly different: 45.0, 41.5, 57.9 and 39.5% in lambing rates for MAP, FGA, CIDR and P sponge, respectively. Also, no significant differences in prolificacy were observed among the four intravaginal devices. These results indicate that the fertility of ewes treated with the four different intravaginal devices including a self-made P sponge and inseminated with frozen semen is similar, although the onset time of estrus and the LH surge varies with the use of progesterone- or progestogen-impregnated intravaginal devices.

Effect of eCG on the pregnancy rate of ewes transcervically inseminated with frozen-thawed semen outside the breeding season

An experiment was conducted to determine whether factors affecting pregnancy rate out-of-season are associated more with transcervical artificial insemination (T-AI) procedures or with the reproductive state of the ewe. Twenty Finncross ewes were treated with progesterone sponges, and at sponge removal (0 h) 10 ewes were treated with eCG. Blood samples were collected for LH and progesterone analyses, and follicular development was monitored using ultrasonography. Ewes were inseminated from 48 to 52 h with 200 million motile frozen-thawed spermatozoa. The incidence of estrus, LH surges and ovulation was greater (P<0.01) and intervals to these responses were shorter (P<0.01) in the eCG-treated ewes. The number of follicles >5 mm was higher (P<0.05) in eCGtreated than control ewes. Progesterone concentrations increased and remained elevated through Day 19 in 7 eCG-treated and in 1 control ewe, and these ewes were pregnant based upon ultrasonographic examination. The results demonstrate that the T-AI technique using frozen-thawed semen produces a relatively high (70%) pregnancy rate out-of-season. The pregnancy rate was found to reflect primarily the reproductive condition of the ewe.

Regulation of prostaglandin endoperoxide H synthase 1 and 2 by estradiol and progesterone in nonpregnant ovine myometrium and endometrium in vivo.

PG endoperoxide H synthase-2 (PGHS-2) messenger RNA (mRNA) and protein levels are increased dramatically in ovine myometrium and endometrium during both glucocorticoid-induced premature labor and spontaneous term labor. In this study, we examined estradiol and progesterone regulation in vivo of PGHS-1 and PGHS-2 expression at both mRNA and protein levels using a nonpregnant ovariectomized sheep model. We determined the differential distribution of PGHS-2 and PGHS-1 in ovine myometrium and endometrium with immunocytochemistry. Twenty ovariectomized ewes were treated with saline (n = 5) or estradiol infused i.v. for 2 days (50 microg/day; n = 5) or an intravaginal progesterone sponge for 10 days (containing 0.3 g progesterone; n = 5) or an intravaginal progesterone sponge for 10 days with estradiol (50 microg/day) administered on days 9 and 10 with the progesterone sponge still in place (EP; n = 5). PGHS-1 and -2 mRNA and protein were measured by Northern and Western blot analyses, respectively. PGHS-2 mRNA and protein abundance increased significantly in myometrium after estradiol treatment (P < 0.01). In contrast, progesterone was a more potent stimulator than estradiol of PGHS-2 protein abundance in endometrium (P < 0.01). PGHS-1 concentration did not change after estradiol and/or progesterone administration (P > 0.05). PGHS-2 was immunolocalized in myometrial cells and endometrial glandular epithelial cells, whereas immunoreactive PGHS-1 was located in the myometrial cells, endothelial and smooth muscle cells of blood vessels, as well as epithelial cells of glands and stromal cells in endometrium. Estradiol-dependent activation of PGHS-2 gene expression resulted in increased PGHS-2 levels in sheep myometrium in vivo. Progesterone did not have any effect on PGHS-2 gene expression in the myometrium. In contrast, progesterone was a more potent stimulator of endometrial PGHS-2 abundance than estradiol. Estradiol and progesterone did not regulate PGHS-1 expression in either endometrium or myometrium. The distribution and differential regulation of PGHS-1 and -2 in myometrium and endometrium are consistent with the differential functions of both enzymes.

Reproductive performance and productivity of Menz sheep in the Ethiopian highlands

Ewe lambs attain puberty at 10 months and 16.9 ± 0.1 kg (56% of mature weight) and first lamb at 15 months. Postpartum anoestrus is 76 days, lambing interval is 8.4 months and 65% of ewes lamb three times in 2 years with a gestation period of 149 days. Ewes cycle year-round but oestrus activity declines from June to September due to increased silent ovulations. Fertilisation rates are high (⩾90%) but lambing rate is 72%, suggesting moderate embryonic mortality. Conception rates to first, second and third oestrus postpartum are 78%, 18% and 4%, respectively. Litter size (prolificacy) is 1.12 but can be increased by 10–40% through premating ewe nutrition management or treatment with gonadotropins. Ewe oestrus activity can be synchronised by ram introduction after a period of isolation and with progesterone sponges or prostaglandin F 2α therapy. Lambs average 2.0 ± 0.1 kg at birth but preweaning mortality (15%) and slow growth, resulting in 8.6 kg weaning weight, still limit overall productivity index to 11.0 ± 0.87 kg per ewe per year, and the annual reproductive rate to 1.4 lambs per ewe. In the traditional management system, where most animals are raised, further studies are required into better nutrition and control of diseases (endoparasitism) in young animals to increase reproductive efficiency, flock productivity and number of animals for finishing and slaughter. This could serve as a model for interventions in other ruminants in the agroecological zone.

Seasonal Variation in the Timing of Estrous Behavior LH Surge and Ovulation Following the Treatment with Progesterone and PMSG in Suffolk Ewes.

Forty-two ewes were treated with intravaginal insertion of progesterone sponge and single injection of pregnant mare serum gonadotropin (PMSG) either in May (mid-anestrus; Group 1, n=14), in July (late-anestrus; Group 2, n=13) or between October and December (breeding season; Group 3, n=15). The sequence of estrus, LH surge and ovulation, thus induced in each group was compared with that in untreated cycling ewes during the breeding season (Group 4, n=10). Although intervals from the sponge removal to the onset of estrus (22.3-25.5 h) and to the LH peak (23.3-28.5 h) were not different among groups, the duration of estrus in Group 1 (19.3 ± 4.4 h) was shorter (P<0.05) than Groups 3 and 4. The intervals between the onset of estrus and the peak of cervical mucus secretion were also shorter in Groups 1 and 2 as compared with Group 4. The number of ewes ovulated during the period between 40-50 h after sponge removal was less (P<0.05) in Group 1 than Groups 2 and 3 . The conception rates were 62.5, 83.3, 100 and 100 % in Groups 1, 2, 3 and 4, respectively. The present results suggest that synchrony among timing of estrous behavior, LH surge and ovulation following the progesterone and PMSG treatments become less coordinated during anestrous season, which could be one of the primary factors responsible for low conception rate in these animals.

The influence of monensin and lasalocid on the breeding performance of ewes and the endocrine status of ewe lambs

Two experiments were performed, in December and August, to determine the effects of dietary ionophores on the breeding performance of ewes and the endocrine status of ewe lambs. Experiment 1 employed 127 mixed-parity ewes fed diets containing 33 ppm monensin (M, n = 43), 45 ppm lasalocid (L, n = 43) or no additive (C, n = 41). Estrus was synchronized with progesterone sponges and the ewes were allowed to breed. The proportion of ewes conceiving at their first estrus was higher (P &lt; 0.05) for control ewes than for L ewes (70.7 vs. 51.2%) M ewes being intermediate (53.5%). Litter size of ewes conceiving at first estrus was not affected by treatment. Experiment 2 employed 57 ewe lambs allocated in a 3 × 2 factorial arrangement to be fed rations containing 33 ppm M, 45 ppm L or no additive for 26 d and to receive, or not, an injection of 50 μg GnRH at 21 d. For lambs receiving GnRH, blood samples were taken every 15 min for 2 h from 30 min pre-injection. At 72 h after GnRH injection, all lambs received an injection of 50 μg estradiol-17β. Further blood samples were taken from all lambs at 4-h intervals for 48 h. Serum LH and FSH concentrations increased from pre-injection means of 1.6 ± 0.2 and 7.8 ± 1.2 ng mL−1 to 20.9 ± 1.9 and 13.4 ± 1.4 ng mL−1, respectively, by 15 min after GnRH injection. These responses were not affected by either ionophore. The estradiol-induced LH surge height was reduced (P &lt; 0.01) in lambs that had received GnRH. These data indicate that at the dietary inclusion levels employed, ionophores may be contra-indicated in the breeding ration. Key words: Ionophores, ewes, reproduction

Further Characterization of the Electromyographic Activity of the Myometrium and Mesometrium in Nonpregnant Sheep under Estrogen Supplementation1

The effects of estrogen administration on uterine contractility varies with animal species. In nonpregnant ovariectomized sheep, estrogen administration has been reported either to inhibit, inhibit then stimulate, or only stimulate uterine contractility. The aim of the present study was to determine the effects of prolonged estrogen administration in the electromyographic (EMG) activity recorded from the myometrium and mesometrium in nonpregnant ovariectomized sheep after estrous synchronization by inserting vaginal progesterone sponges 14 days before surgery. Surgery was performed on four ewes under halothane anesthesia. Bilateral oophorectomy was performed, and stainless steel EMG electrodes were sewn to the mesometrium and myometrium in both left and right horns of the uterus. Blood samples were taken at 1000 h from the uterine vein for 13,14-dihydro-15-keto-prostaglandin F2 alpha determination, and from the femoral artery for estradiol determination. Starting on Day 7 after surgery, estradiol 17 beta (50 micrograms/24 h) was infused continuously into the jugular vein. Estrogen administration had a different effect on the EMG activity recorded from myometrium and mesometrium. The myometrial response to estrogen was an increase in the frequency of short EMG events from 19.0 +/- 8.7 to 57.0 +/- 5.0 (p less than 0.05) for events less than 60 sec, and from 2.70 +/- 0.83 to 10.30 +/- 1.36 (p less than 0.05) for events lasting greater than 60 sec but less than less than 180 sec. In contrast, there was no stimulatory effect of estrogen on mesometrial EMG for both types of short events less than 60 sec, and greater than 60 but less than less than 180 sec.(ABSTRACT TRUNCATED AT 250 WORDS)

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.

Radioimmunoassay and enzymeimmunoassay of plasma progesterone as monitors of progesterone sponge treatment in ewes

The daily plasma progesterone (P) concentrations achieved during insertion of P (750 mg) sponges into two groups of ewes were examined. Group I received prostaglandin (PG) treatment, which was required to suppress the P production (to levels of < 0.3 ng hormone/ml plasma) from the corpora lutea (CL) of a previous superovulation treatment, following which these Group I ewes and the anestrous Group II ewes were sponge treated. Radioimmunoassay (RIA) and enzymeimmunoassay (EIA) were used to measure the P levels in both groups. Progesterone (750 mg) sponges with and without citric acid impregnation were inserted into all the ewes for 12 days (d). Citric acid lowered the P levels reaching the plasma from the sponges, but it did not mask the characteristic profile (during the treatments) determined by the states of the ewes (single PG and double PG injected, Group I or in the anestrous Group II). The plasma P levels in Group I and II ewes rose to at least 7.0 ng/ml at intervals during treatment. The duration and magnitude of the P concentrations in the plasma were higher in the single PG compared with the double PG ewes during sponge insertion in Group I. The anestrous Group II ewes showed two major peaks (Day 1, P<0.01 and Days 11 to 12, P<0.05) during sponge treatment. A P level > 2.0 ng/ml was maintained over the entire treatment in the single PG and in the anestrous hormone-treated ewes, and was of shorter duration (7 d) in the double PG-treated animals. These endogenous patterns in P profiles of the ewes indicate that the hormone level during sponge insertion varies in magnitude and duration, parameters determined by the physiological/endocrinological state of the ewes at the start of the treatment. The EIA correlated significantly (P<0.001) with the RIA for the measurement of P concentration, when analyzed daily on an individual animal basis.

Effects of progesterone-impregnated sponge treatment on peripheral plasma hormone levels and fertility in the cyclic ewe

Cyclic ewes were treated with 500-mg progesterone-impregnated sponges for the synchronization of oestrus. In the first experiment, the sponges were removed from 79 ewes at intervals over a 17-day treatment and the residual amount of progesterone was measured in order to assess the rate of absorption of the hormone from the sponges by the animals. The residual progesterone was found to decrease linearly with the duration of sponge insertion but there was also a significant quadratic component indicative of a slowing down in the rate of progesterone absorption towards the end of the treatment period. In the second experiment, 13 cyclic ewes were treated with 500-mg progesterone sponges for 17 days and the eight ewes in oestrus following spongewithdrawal were mated. The peripheral plasma progesterone was assayed at intervals during sponge insertion and at weekly intervals after sponge withdrawal. The residual progesterone levels on the sponges and the plasma progesterone levels of the treated ewes were examined in relation to their oestrous response and fertility. There was a significantly higher residual level of hormone remaining on sponges from ewes that mated than on sponges from those that did not (P < 0.01). The 13 ewes exhibited luteal phase levels of plasma progesterone when assayed during the period of sponge insertion regardless of their response to treatment. The mated, fertile ewes had significantly higher plasma hormone levels than the non-mated and the mated infertile ewes, after sponge withdrawal.

Induction of oestrus in Saanen goats at early breeding season by intravaginal progesterone sponges (MAP) or by prostaglandin F 2α injections. Effect on different age groups

Twenty-one maiden and 29 pluriparous milking Ankara Saanen goats received either two i.m. injections of PGF 2α (n=25) or intravaginal MAP sponges (n=25) early in November at the start of the breeding season. About twice as many pluriparous goats as maiden goats exhibited estrus after either treatment (87% vs. 47%). Breeding after this induced estrus caused pregnancies in 62% of the pluriparous goats, but only in 24% of the maiden animals. Maximal concentrations of progesterone were reached 11 days after the start of the MAP treatment. Progesterone declined to basal levels two to four days after sponge withdrawal. A significant slower progesterone increase also resulting in lower maximal concentrations could be observed in maiden goats. Luteolysis was evident in all animals within 24 h after PGF 2α injection. Nine goats (six maiden and three pluriparous) did not exhibit Heat after the second injection and showed only a slow increase of progesterone. It seems that noncyclic animals are less sensitive to MAP treatment than to the first PGF 2α injection. Goats at the beginning of the breeding season may react after a premature interruption of corpus luteum function (after second PGF 2α injection) with delayed or inadequate follicular function.