Induction of oestrus by administering Inhibin antiserum along with equine chorionic gonadotropin in anoestrous bitches

As dogs experience oestrus only once or twice a year, it is necessary to establish an effective method of oestrous induction for efficient breeding. In the present study, we evaluated inhibin antiserum (IAS) on oestrous induction in anoestrous females. Bitches were administered 0.5 ml/kg IAS or a mixture of 50 IU/kg equine chorionic gonadotropin (eCG) and 0.5 ml/kg IAS and 500 IU human chorionic gonadotropin (hCG) administered 7 days after the mixture injection. As a control, bitches received 50 IU/kg eCG, with 500 IU hCG administered 7 days after eCG injection. Blood-tinged vaginal discharge, vulvar swelling, plasma progesterone concentrations and ovarian follicular development were assessed from day 0 to day 14. IAS alone injection did not induce oestrus in bitches at the anoestrous stage. Conversely, vulvar swelling, blood-tinged vaginal discharge and an estimated luteinizing hormone (LH) surge appeared on days 3–7, days 3–6 and days 7–9 after the IAS+eCG mixture injection, respectively, in all five bitches at the anoestrous stage. The average number of developing and ovulated follicles in bitches administered IAS+eCG was 8.8 and 9.6 respectively. A single eCG injection followed by hCG induced oestrous signs, with an average of 8.3 developing follicles and 4.5 ovulated follicles. This study revealed that IAS alone did not induce oestrus, but when IAS was used in combination with eCG, it induced oestrus and promoted a considerable number of ovulations in anoestrous dogs.     

THE INDUCTION OF OESTRUS AND OVULATION IN THE BITCH USING PREGNANT MARE SERUM GONADOTROPHIN AND HUMAN CHORIONIC GONADOTROPHIN

Seventeen bitches (11 anoestrous, 4 prepubertal, 1 pregnant and 1 postpartum) were treated with pregnant mare serum gonadotrophin (110 iu/kg) at weekly intervals up to the occurrence of oestrus or a maximum of 3 treatments. Oestrus was induced in 8/11 anoestrous bitches only. The between bitch ovarian response was very variable. Ovulation occurred in 7/8 PMSG induced oestrous bitches. The 3 oestrous bitches treated with human chorionic gonadotrophin (500 iu) at the start of oestrus had a better ovulatory response than those treated with PMSG alone.     

Evaluation of Cabergoline and Buserelin Efficacy for Oestrous Induction in the Bitch

The purpose of this work was to compare two different protocols of oestrous induction, using either a dopamine agonist (cabergoline) or a GnRH agonist (buserelin) in anoestrus bitches. The clinical trial involved 22 Beagle bitches, randomly allotted to two treatment groups: group A (n = 12) was orally administered cabergoline (Galastop^®; Centralvet‐Vetem, Milan, Italy; 5 μg/kg SID), until the onset of cytological oestrus or for a maximum of 30 days and group B (n = 10) was treated with buserelin acetate, (Suprefact^®; Aventis Pharma, Milan, Italy), administered subcutaneously t.i.d., at 1.5 μg/kg for 11 days and 0.75 μg/kg for the following 3 days. Blood samples were collected twice a week to measure progesterone and prolactin concentration. Both cabergoline and buserelin produced a significant early decline in prolactin concentration (p < 0.01), but the effect of cabergoline lasted longer. Progesterone concentration was significantly affected by buserelin administration, showing a significant increase (p < 0.01) from day 3 to day 6 of treatment. Cabergoline confirmed its effectiveness in inducing oestrus as 10 of 12 bitches responded to the treatment, were mated and whelped. On the contrary, oestrus was observed in only three of 10 buserelin‐treated bitches and in two of them 7 and 13 days after the end of treatment. These same two bitches accepted mating and conceived. The results suggest that in a clinical setting, dopaminergic treatment is the treatment of choice as it yields more consistent results and involves a much easier administration protocol.     

Equine Chorionic Gonadotropin and Human Chorionic Gonadotropin Stimulation Increase the Number of Luteinized Follicles and the Progesterone Level Compared with Cabergoline Stimulation in Anoestrus Bitches

In this study, ovarian morphologies and blood progesterone concentrations following oestrous induction in bitches were examined. Fifty‐three clinically healthy anoestrus bitches received cabergoline at a daily dose of 5 μg/kg of body weight per os for 21 days (group I) or subcutaneous equine chorionic gonadotropin at a dose of 20 IU/kg of body weight for five consecutive days with an additional 500 IU s.c. per bitch of human chorionic gonadotropin on the last day of treatment (group II). Twenty bitches that spontaneously displayed oestrous signs were left untreated and served as controls (group III). The induced oestrous rates and ovulation rates in groups I and II were 60.0% vs 64.3% and 86.7% vs 83.3%, respectively. Morphological assessments of the ovarian structures after ovariohysterectomy revealed an increase in the number of luteinized follicles and cysts in group II compared with the two other groups (p < 0.001). In contrast, the numbers of corpora lutea and follicles were similar in all groups. In accordance with the above‐mentioned alteration, the progesterone concentration in the gonadotropin group (II) was increased (p < 0.001) in the periovulatory period compared with the other two groups. During the entire sampling period, the progesterone profiles in the cabergoline (I) and control (III) groups were similar and typical of normally cycling bitches. In conclusion, gonadotropin treatment is associated with an increased progesterone level during the periovulatory period that probably originates from luteinized follicles, whereas cabergoline treatment induces cycles with both physiological progesterone concentrations and ovarian morphologies.     

Coat colour changes associated with cabergoline administration in bitches

Cabergoline or bromocriptine were administered orally to 60 bitches at doses of 5 microg/kg and 15 microg/kg daily, respectively, for two to 45 days for the treatment of pseudopregnancy or for oestrus induction. Seven of the dogs which received cabergoline for more than 14 days developed coat colour changes from the second week of administration to the next coat shedding. Of these, fawn-coloured bitches developed a yellowish coat colour while Argentine boar hounds became black spotted, mainly on their extremities. In previous untreated oestrous periods, these bitches had shown no coat colour changes. It is concluded that a colour shift in certain haircoats of particular breeds could be mediated through the inhibition of the secretion of melanocyte-stimulating hormone by the administration of the dopaminergic agonist cabergoline for more than two weeks. Transient coat colour changes should be considered a possible side effect when planning long-term treatment with dopaminergic agonists in dogs.     

Comparisons of different combinations of analogues of PGF2 alpha and dopamine agonists for the termination of pregnancy in dogs.

Groups of five pregnant bitches were treated to terminate the pregnancy with four combinations of drugs, starting 28 days after the estimated surge of luteinising hormone (LH), 22 to 28 days after the first mating. The treatments were: cabergoline administered orally for 10 days at a dose of 5 micrograms/kg and a single subcutaneous injection of 2.5 micrograms/kg cloprostenol at the start of the treatment; the same dose of cabergoline plus two doses of 1 microgram/kg cloprostenol administered on days 28 and 32 after the LH surge; bromocryptine administered orally at a dose of 30 micrograms/kg three times a day for 10 days plus a single dose of 2.5 micrograms/kg cloprostenol; the same dose of bromocryptine plus two doses of 1 microgram/kg cloprostenol; and a group of five pregnant bitches was left untreated. The pregnancies were terminated in all but one of the treated bitches, in each case by resorption of the fetuses. There were few side effects in the bitches treated with two doses of 1 microgram/kg cloprostenol, and were present but acceptable in those treated with one dose of 2.5 micrograms/kg. Plasma progesterone concentrations decreased to less than 1 ng/ml within 72 hours of the start of treatment and remained low except in the bitch in which pregnancy was not terminated. In the five untreated bitches, plasma progesterone remained high and they whelped normally. In the treated groups, the intervals between successive displays of oestrus were reduced by approximately 70 days in comparison with previous cycles or with the control group, but the fertility of the dogs was not affected adversely.     

Calving rates of Brahman and Brahman-cross cows to fixed-time insemination after treatment with pregnant mare serum gonadotrophin and intravaginal progesterone

In 2 experiments involving 151 non-lactating and 107 lactating Brahman or Brahman-cross cows, the effects of progesterone treatments (PRID) of 2 durations (7 v 14 days) and injections of pregnant mare serum gonadotrophin (PMSG) at 3 doses (O v 375 v 750 IU) were examined. All cows were inseminated with frozen/thawed semen 54 to 58 and 70 to 74 hours after PRID removal. Calving rates of non-lactating cows (38%) were unaffected by breed or treatment but were higher in previously cyclic than acyclic cows (44% v 19%, P less than 0.025) and in cows which exhibited oestrus after treatment (52% v 23%, P less than 0.001). Calving rates of lactating cows were not affected by these factors but were affected by treatment; PMSG produced no significant effect after a 7-day PRID treatment (33% overall) but increased calving rates after 14-day PRID treatments (22% v 46% v 37% for 0, 375 and 750 IU respectively, P less than 0.10). Comparisons of calving rates of lactating cows treated with 14-day PRID and PMSG and artificially inseminated, and untreated naturally mated cows, showed that treatment significantly increased the proportion of cows conceiving in the first 35 days of the mating period (50% v 23%, P less than 0.025). The results show that treatment with PRID for 14 days and PMSG can overcome post-partum anoestrus in lactating Brahman and Brahman-cross cows leading to significant reductions in the calving to conception interval.     

Treatment of spontaneous pyometra in 22 bitches with a combination of cabergoline and cloprostenol

Twenty-two bitches with ultrasonographically diagnosed spontaneous pyometra were treated with a combination of 5 microg/kg cabergoline per day and 5 mug/kg cloprostenol every third day, and potentiated sulphonamide twice a day. Bitches with either open-cervix or closed-cervix pyometra showed a rapid clinical improvement, associated with a reduction in plasma progesterone concentration, increased vulval discharge and a reduction in the diameter of the uterus. The haematological profiles of 21 of the bitches returned to normal within six days of treatment, and their biochemical profiles returned to normal within nine days; 19 of the bitches were managed successfully by a 10-day period of treatment. Two bitches required a further three days of treatment, and in one bitch with a partial uterine torsion the treatment was not successful. Adverse effects of the treatment were limited to the 60 minutes immediately after the administration of prostaglandin, and included retching, vomiting, mild abdominal straining, diarrhoea and panting. The incidence of adverse effects was reduced after each successive dose of prostaglandin. Eleven of the 21 successfully treated bitches were mated at the next oestrus, and seven became pregnant; their litters were smaller than the published breed averages. In four of the bitches the pyometra recurred after the next oestrus.     

The effect of the seasons on the ovarian response in sheep after the administration of the serum gonadotropin, PMSG

In the autumn oestrus season, 20 Slovak Merino ewes were exposed to synchronization of oestrus, treated with the PGF2alfa at doses 125 micrograms (Oestrophan, inj. Spofa). followed by an injection of PMSG at doses 1000 IU (Antex Leo Denmark) and 50,000 IU of Vitamin A (Axerophtol Spofa). 23 anoestrus ewes were synchronized with an intravaginal sponges containing 20 mg of chlorsuperlutine (Agelin, Spofa) for 12 days and after sponge withdrawal, the ewes were injected with 750 and 1000 IU of PMSG (Antex Leo Denmark). Ovulatory response was observed and the possibility of ova recovered from the genital organs in ewes after synchronization of oestrus and superovulation in oestrus season. Higher values of the total follicular response (CFO), and the average number of ovulation (PO) after administering equal doses of PMSG were found out both in anoestrus ewes (CFO 6.62 +/- 4.24; PO 4.25 +/- 4.52) and in oestrus ewes (CFO 2.70 +/- 2.10; PO 2.60 +/- 1.74; resp. CFO 2.80 +/- 1.83; PO 3.4 +/- 3.0), if the ewes were treated with PMSG together with vitamin A. The average number of ova flushed was higher in anoestrus ewes (3.0-0.5) than in oestrus ewes (1.67-3.75). In both trials the equal ratio in the number of released ova was gained from ewes of experimental groups (83-88% of the total number). After ova flushing from the genital organs in ewes of the experimental groups most ovas were found in the isthmatal part of the uterine tube (36-60%). On the basis of gained results it was concluded, that synchronized oestrus ewes on receiving PMSG in anoestrus season the ovarial response was more significant than in autumn breeding season.     

Reproductive performance of anoestrous high-producing dairy cows improved by adding equine chorionic gonadotrophin to a progesterone-based oestrous synchronizing protocol

This study sought to improve the reproductive performance of anoestrous high-producing dairy cows by including equine chorionic gonadotrophin (eCG) after progesterone-releasing intravaginal device (PRID) removal. In Experiment I, 806 cows at 51-57 days post-partum were randomly assigned to a PRID (treated with PRID), PRID-500 (treated with PRID plus 500 IU of eCG) or PRID-750 (treated with PRID plus 750 IU of eCG) group. In Experiment II, 422 cows showing a long anoestrus period (animals with no oestrus signs nor luteal tissue 35 days before treatment) were randomly assigned to the PRID, PRID-500 or PRID-750 groups. The dependent variables considered in binary logistic regression analyses for both experiments were the rates of oestrus, ovulation and conception after treatment, the cumulative conception rate on Day 120 post-partum and pregnancy loss. In Experiment I, interaction between treatment and season showed a significant effect on the oestrous response. Thus, during the warm season, PRID group cows were 8.9 times more likely to express oestrus than the remaining cows. Moreover, inseminated cows with two or more corpora lutea 8-14 days after treatment were more likely to become pregnant (by a factor of 2.4) than cows with a single corpus luteum. Finally, cows without luteal structures treated with PRID were 0.4 less likely to be pregnant on Day 120 post-partum, compared with the remaining cows. In Experiment II, cows in the PRID group treated during the warm or cool season were less likely to exhibit oestrus (by a factor of 0.06 or 0.2, respectively) or ovulate (by a factor of 0.004 or 0.14, respectively) than the remaining cows. In conclusion, in anoestrous cows in both experiments, the addition of eCG to the use of an intravaginal progesterone device to induce oestrus was beneficial. The recommended dose of eCG is 500 IU.     

Effects of Gonadotrophin Releasing Hormone Administration on the Pituitary-Ovarian Axis in Anoestrous vs Ovariectomized Bitches

The aim of this study was to determine the effects of gonadotrophin releasing hormone (GnRH) administration on the plasma concentrations of reproductive hormones in intact and ovariectomized (OVX) bitches. Therefore, blood samples were collected at multiple times before and after the administration of 10 microg/kg GnRH (Fertagyl)) for the determination of the plasma concentrations of luteinizing hormone (LH), oestradiol, progesterone and testosterone in six anoestrus and in six OVX bitches. The mean plasma LH concentrations before and 60 min after GnRH administration were significantly lower in the anoestrous bitches than in the OVX bitches. In both groups GnRH administration resulted in a significant increase in the plasma LH concentration. The highest plasma LH concentrations were found at 10 min after GnRH administration and these values did not differ significantly between the two groups. Only in the anoestrous bitches a significant increase in plasma oestradiol concentrations was found after GnRH administration and these values were significantly higher than those in the OVX bitches. The plasma concentrations of progesterone and testosterone were low (close to or below the limit of quantitation) both before and after GnRH administration and the differences between anoestrous and OVX bitches were not significant. It can be concluded that (i) basal plasma LH concentration is significantly higher in OVX bitches than in anoestrous bitches, (ii) plasma LH concentration increases after GnRH administration in both anoestrous and OVX bitches, (iii) GnRH administration causes a significant rise in plasma oestradiol concentration only if ovarian tissue is present and (iv) measurement of plasma progesterone and testosterone concentrations before and after GnRH administration does not aid in distinguishing between anoestrous and OVX bitches. The results of this study may provide a basis for the diagnosis of remnant ovarian tissue and verification of neuter status in the bitch.     

Use of cabergoline to treat primary and secondary anestrus in dogs

OBJECTIVE: To determine whether cabergoline would be safe and effective for induction of estrus in dogs with primary or secondary anestrus. DESIGN: Prospective case series. ANIMALS: 6 privately owned otherwise healthy pure-bred dogs with primary or secondary anestrus. PROCEDURE: Dogs were treated with cabergoline (5 microg/kg [2.3 microg/lb], p.o., q 24 h) until 2 days after the onset of proestrus. Follicular development was assessed by means of cytologic examination of vaginal smears; ovulation was assessed by measuring serum progesterone concentration 3 weeks after the onset of estrus. Five bitches were mated during behavioral estrus. RESULTS: All dogs had normal estrus periods, and all 5 dogs that were mated whelped normal litters. Mean duration of cabergoline treatment was 16 days. None of the dogs had any adverse effects associated with cabergoline administration. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that administration of cabergoline is safe and effective for treatment for primary and secondary anestrus in dogs.     

Attempted oestrus induction in four bitches using pregnant mare serum gonadotrophin

Two juvenile (9 months) and two adult (3 years) beagle bitches were injected with five doses (250 i.u. per dose) of pregnant mare serum gonadotrophin (PMSG) on alternate days. Plasma oestrogen concentrations rose in all bitches. In one adult bitch plasma progesterone concentrations remained basal and no signs of oestrus were shown; in the other there was a slight elevation of circulating progesterone values and she showed oestrus but did not conceive. Both the young bitches came into heat and had multiple ovulations, producing very high plasma progesterone concentrations. One of them conceived, and at laparotomy on the thirty-sixth day after the first mating seventeen conceptuses were seen; 14 days later ovarohysterectomy was performed and only five foetuses remained in the uterus.     

Effect of naloxone, nalbuphine, progesterone and pregnant mare's serum gonadotrophin on the sexual behaviour of ewes

Sheep were medicated with progestogen sponges, pregnant mare's serum gonadotrophin, naloxone or nalbuphine during April, May, June or September 1986. It was observed that when suckling ewes were treated three or five weeks post partum with 45 mg medroxyprogesterone acetate (incorporated on an intravaginal sponge) for 12 days followed by 500 iu of pregnant mare's serum gonadotrophin and 0.4 mg naloxone administered intramuscularly after the withdrawal of the sponge, oestrus became evident 24 to 48 hours after the sponges were withdrawn. However, when the naloxone was replaced by 10 mg nalbuphine administered intramuscularly, oestrus was not shown. When the ewes were medicated with the same combination of drugs during anoestrus, the result was similar to that observed during lactation and oestrus was displayed only in the ewes that received naloxone. Thus the opioid antagonist naloxone facilitates the expression of oestrus in the ewe during anoestrus and lactation.     

Effect of an Injectable Cabergoline Formulation on Serum Prolactin (PRL) and Milk Secretion in Early Postpartum Beagle Bitches

This study was conducted in order to evaluate effects on prolactin (PRL) concentration and mammary milk secretion of an injectable cabergoline formulation administered to five lactating Beagle bitches during early postpartum (PP). Bitches were bled twice daily (from PP day 3 to PP day 12) and then daily (from PP day 13 to PP day 16) to assay serum PRL. On PP day 6, a subcutaneous (SC) injection of 0.1 ml/kg of placebo was administered. On PP day 9, a SC 0.1 ml/kg dose of injectable cabergoline was administered. All bitches were checked for milk production, using a clinical scoring in order to quantify milk expression from each teat. A circadian variation of serum PRL was evident during the 6 days of pre-treatment monitoring. The day after cabergoline injection, an 80% decrease of PRL serum concentration was observed (p < 0.05). The circadian oscillatory pattern of PRL secretion disappeared after administration of cabergoline, and PRL values remained significantly lower than in the previous days for the first 60 h following treatment (p < 0.001). Milk production was drastically reduced when comparing pre-treatment to post-treatment scores (p < 0.001). A single dose of injectable cabergoline caused a significant reduction in serum PRL concentration and a significant reduction in milk flow. The injectable formulation of cabergoline appeared to be safe and well tolerated.     

Measurement of plasma oestradiol after an injection of a gonadotrophin as a test for neutered bitches

Twenty-eight bitches with unknown reproductive histories were injected intravenously with either human chorionic gonadotrophin (hCG) or equine chorionic gonadotrophin (eCG) (pregnant mare's serum gonadotrophin) and their oestradiol responses were measured at the time of the injection and 90 minutes later. They were at various stages of the oestrous cycle as determined by histology and a progesterone assay for luteal function. Twenty-six of them were considered to be entire because they showed either an increase in plasma oestradiol over preinjection values or steady high values. The ovaries were removed from 25 of these animals and the other probably had a remnant of ovary because it came into oestrus some weeks later. In two remaining bitches no oestradiol could be detected either before or after the injection of gonadotrophin and they were predicted to have been neutered, which was confirmed at laparotomy. In the entire bitches, the highest plasma oestradiol concentration was measured during metoestrus and the lowest during anoestrus.     

Effect of hCG Treatment on the Oestrous and Ovulation Responses to FSH in Prepubertal Gilts

To ensure sufficient numbers of pregnant females, particularly at hotter times of the year, hormonal induction of gilt oestrus may be necessary. However, the gilt oestrus and ovulation responses to gonadotrophin treatment have often proven unpredictable. The objective of this study was to examine possible reasons for this unpredictability. Prepubertal gilts (approximately 150 days of age, n = 63) were assigned to one of three treatments: injection of 300 IU hCG (n = 15); pre-treatment with 100 mg FSH in polyvinylpyrrolidinone administered as 2 × 50 mg injections 24 h apart, followed by 600 IU eCG at 24 h after the second FSH injection (n = 23); or FSH pre-treatment as above followed by 300 IU hCG at 24 h after the second FSH injection (n = 25). To facilitate oestrus detection, gilts were exposed to a mature boar for 15 min daily for 7 days. Blood samples were obtained on the day of eCG or hCG injection and again 10 days later and gilt ovulation responses determined based on elevated progesterone concentrations. The oestrus responses by 7 days were 6.7%, 17.5% and 64.0% for gilts treated with hCG, FSH + eCG and FSH + hCG, respectively (p < 0.001). The oestrous gilt receiving hCG alone and one oestrous FSH + hCG gilt did not ovulate, all other oestrous gilts ovulated. A further two anoestrous FSH + eCG-treated gilts ovulated. These data suggest that FSH pre-treatment facilitated the development of ovarian follicles to the point where they became responsive to hCG, but had little effect on the response to eCG.     

Post‐weaning anoestrus in primiparous sows: LH patterns and effects of gonadotropin injection and boar exposure

Summary

Post‐weaning anoestrus was studied in eighteen primiparous sows, selected from a breed showing a high proportion of anoestrous sows. The sows were studied from late lactation, through weaning at day 29 post‐partum (p.p.), until day 21 post‐weaning (p.w.). Blood samples were taken once daily, and frequently (every ten minutes) on several days before and after weaning.

Out of a total of ten anoestrous sows, three were exposed to a boar and seven were given gonadotropins (PG600) on day 21 p.w.. Serial blood samples were analysed for LH only and daily samples were additionally analysed for oestradio1–170 and progesterone, by validated radioimmunoassay procedures. Analysis of variance of the basal level, pulse frequency, pulse amplitude and mean level of LH showed, retrospectively, that during lactation the basal and mean levels of LH were significantly lower in anoestrous than in oestrous sows (P ≤ 0.05). Furthermore, the post‐weaning basal and mean levels of LH were also significantly lower in anoestrous than in oestrous sows (P ≤ 0.05). However, because of the small number of oestrous animals (n = 3), these results should be interpreted with caution.

Exposure of anoestrous sows to a boar did not result in oestrus and/or ovulation within seven days, but did increase LH pulse frequency. Injection of gonadotropins resulted in an LH surge, oestrus and ovulation in only three sows, but oestradiol levels were increased in six sows. From our experiments and from reports in the literature we conclude that a lowered secretion of LH may play a role in the aetiology of post‐weaning anoestrus in the sow.     

Ovulatory Response and Embryo Yield in Jakhrana Goats Following Treatments with PMSG and FSH

Superovulatory response and embryo production efficacy were investigated in adult (age 2–4 years, average body weight: 27–43 kg) cycling Jakhrana goats (n = 15) under semi-arid environmental conditions of India by administering different superovulatory regimens. Goats were reared under semi-intensive system of management in established farm conditions. To synchronize oestrus, a luteolytic dose of carboprost tromethamine (Upjohn, UK) was administered intramuscularly to all does at the dose rate of 5μg per kg body weight in a double dose schedule with an interval of 11 days. For superovulation, 750 IU of PMSG (Folligon, Intervet, Boxmeer, Holland) per goat was administered intramuscularly 24 h before administering a second dose of luteolytic agent in five does (treatment 1). FSH (Sigma, St. Louis, MO, USA) 12.50 IU per goat was administered intramuscularly in a decreasing daily dose schedule (2.50, 2.50; 1.875, 1.875; 1.25, 1.25; 0.625, 0.625) at 12 h intervals over four days, initiated 48 h before administering second dose of carboprost tromethamine in 5 does (treatment 2). FSH (Super-Ov, Ausa Intern, USA) was administered at a uniform dose rate of 8.33 units per goat intramuscularly at 24 h intervals over three consecutive days (total dose was 25 units), initiated 48 h before administering a second dose of carboprost tromethamine in 5 does (treatment 3). To synchronize ovulation in responders, human chorionic gonadotrophin (hCG, Chorulon, Intervet) was injected intramuscularly at a dose rate of 500 IU in each goat on the day of oestrus appearance. Goats were laparotomized 72–82 h following the onset of synchronized oestrus and their genitalia were flushed using a standard collection procedure. Variability (p > 0.05) in superovulatory response (number of established corpora lutea) was observed: FSH (Sigma), 11.8± 2.9; FSH (Super-Ov), 11.6±4.5; PMSG (Intervet), 8.4±2.3. A similar pattern was reflected in mean embryo and transferable embryo recovery, respectively (p > 0.05): FSH (Sigma), 8.0±1.8, 5.2±1.7; FSH (Super-Ov), 6.6±2.4, 5.4±2.4; PMSG, 5.8±1.9, 3.8±2.2. In PMSG-treated does, comparatively more unfertilized ova or retarded embryos were recovered than in FSH-treated does. The superiority of FSH preparations over PMSG was reflected in terms of total and transferable embryo production (p > 0.05). On average, five transferable embryos (excellent and good quality) were recovered per doe treated with FSH of either source. The mean ova/embryo recovery was satisfactory (55–68%). Results indicated that Jakhrana goats can be superovulated for embryo production using FSH of either source to augment productivity.     

The Effect of Gonadotrophin Releasing Hormone and Follicle Stimulating Hormone in Conjunction with Pregnant Mare Serum Gonadotrophin on the Superovulatory Response in Crossbred Sheep In India

Thirty-two mature crossbred (Fine Wool Synthetic, FWS) sheep developed for fine wool production in India were treated for superovulation and oestrus synchronization in spring season. The ewes were randomly allocated to four treatment groups in a factorially designed experiment. For induction of superovulation, pregnant mare serum gonadotrophin (PMSG) was administered alone (group 1), in combination with gonadotrophin releasing hormone (GnRH) (group 2) or with follicle stimulating hormone (FSH) (group 3) and with both (group 4). Oestrus was synchronized in all the ewes by two injections of prostaglandin F2 (PGF, 10 mg each) administered at an interval of 10 days. Superovulation treatment started 48 h prior to the second PGF injection. The proportion of ewes in oestrus did not differ significantly (p>0.05) in the four groups. The use of GnRH set the ewes into oestrus earlier than the ewes in the other groups. Treatment with PMSG (800 IU) in conjunction with 4 g of Buserilin (GnRH) increased the ovulation rate (9.1±2.6 corpora lutea (CL)) above that observed when PMSG was used alone (3.0±0.7 CL). The use of FSH (0.5 U ovagen) in conjunction with PMSG was characterized by a decrease in the proportion of ewes with 2 CL (4/8 vs 7/8; p<0.05) and in the number of ovulations, i.e. CL observed (2.4±0.6 vs 9.1±2.6), and a nonsignificant increase in the incidence of large follicles (LF) (4.6±1.28 vs 3.25±0.6; p>0.05). The interaction between treatments of FSH and GnRH was not significant (p>0.05).It is concluded that use of GnRH, in conjunction with either PMSG alone or PMSG plus FSH treatment, advanced the onset of oestrus and increased the ovulation rate in FWS sheep.