Effects of intravulvo-submucosal cloprostenol injections on hormonal profiles and fertility in subestrous cattle

Eighty-two subestrous cattle were treated with different doses of cloprostenol through intramuscular (i.m.) and intravulvo-submucosal (i.v.s.m.) injections to study hormonal profile and fertility. The study was divided into two experiments. In Experiment I, 13 cows were treated with one of three doses of cloprostenol (500 mug i.m., 125 and 62.5 mug i.v.s.m.) to measure response of progesterone (P(4)) and estradiol (E(2)). P(4) decreased abruptly and E(2) levels increased from basal levels following injections of the two larger doses of cloprostenol. P(4) decreased to<5 nmol/l approximately 72 h after treatment. E(2) levels increased to >300 pmol/l 24 h after cloprostenol injections except in cows treated with 62.5 mug dose. Close agreement was observed between P(4) profiles and clinical findings following 500 and 125 mug of cloprostenol treatment. In Experiment II, 69 subestrous cows were treated with either 500 mug i.m. or 250, 125 or 62.5 mug i.v.s.m. doses of cloprostenol. The percent of cows in estrus 96 h following treatment were 60, 80, 67.8 and 18%, respectively. A total of 29 cows were artificially inseminated and 41.3% conceived. We concluded that i.v.s.m. injections of cloprostenol at the dosage of 125 mug and above causes luteolysis, induces estrus and establishes fertility in subestrous cattle. The method is economical but time consuming when compared to the intramuscular route.     

Possibility of reducing the luteolytic dose of cloprostenol in cyclic dairy cows

The administration of cloprostenol by intravulvosubmucous (i.v.s.m.) injection at 1 2 and 1 4 of the dose usually given by intramuscular (i.m.) injection, was tested in dairy cows for luteolysis and estrus synchronization. The i.m. injection was used in ten adult cows at the usual dose of 500 mug/animal. Eleven adult cows and 11 heifers were treated i.v.s.m. with a dose equivalent to 250 mug/animal and 125 mug/animal, respectively. Two injections of cloprostenol were administered 11 days apart to the cows not detected in oestrus after a single injection. Forty-three out of the total 46 animals were detected to be in dioestrus at the time of at least one of the injections, as reflected by the plasma progesterone concentrations at the time of treatments. Three out of the 43 animals injected during dioestrus were refractory to the luteolytic effect of cloprostenol; this appeared to be independent of the dosage and the route of administration (refractory cows were: one adult cow treated i.m. and two treated i.v.s.m. with 125 mug of cloprostenol). The mean time interval from injection to the onset of heat was 82.8 hours with a confidence limit for 95% of probability between 67.9 hours and 92.7 hours. The difference between treatments is not significant. The results suggest that in heifers and adult cows cloprostenol can be given i.v.s.m. route at a reduced dose of 1 4 of the usual 500 mug i.m. dosage without affecting the luteolytic effect of the drug or fertility.     

Effects of cloprostenol, human chorionic gonadotropin and estradiol benzoate treatment on estrus synchronization in dairy cows

Two consecutive experiments were conducted. In Experiment 1, 24 Friesian lactating cows were randomly assigned to two groups. Cows in Group I received intramuscularly (i.m.) 500 mcg of cloprostenol, 1250 IU of human chorionic gonadotropin (hCG) and 5 mg of estradiol benzoate 12 h after cloprostenol treatment. Cows in Group II received 750 IU i.m. of hCG and 3 mg of estradiol benzoate 12 h after cloprostenol treatment. Treatment was given on Day 16 after estrus in both groups. All animals showed estrus within 24 to 48 h after cloprostenol treatment. The average interval from cloprostenol injection to the onset of estrus was not influenced by treatments. Four cows in Group I failed to ovulate and became cystic. In Experiment 2, 71 Friesian lactating cows were randomly assigned to two groups. Cows in Group I received 500 mcg i.m. of cloprostenol after corpus luteum detection by palpation per rectum. Cows in Group II received 500 mcg of cloprostenol plus 750 IU of hCG and 3 mg of estradiol benzoate 12 h after. When estrus ready for service was confirmed by rectal examination, cows were inseminated. The percentage of cows ready for service tended to be lower (P < 0.06) between cows in Group I (88%) and those in Group II (100%). The average interval from cloprostenol treatment to service was longest (P < 0.001) in Group I (78.7 h +/- 14.9, X +/- SD) vs Group II (48 h +/- 2.9). The degree of readiness for service synchrony was lowest (P < 0.001) in Group I (59.3%) vs Group II (94.2%). The pregnancy rates of cows synchronized or treated were not altered by hCG-estradiol benzoate treatment (P > 0.25). These results suggest that in dairy cows treated with cloprostenol following palpation per rectum of a corpus luteum and then with 750 IU of hCG and 3 mg of estradiol benzoate 12 h later, a single fixed-time insemination at 48 h after cloprostenol treatment should be performed.     

Doses of prostaglandin analogue “cloprostenol” by intravulvo-submucosal (IVSM) injections effective for the induction of oestrus in goats

In order to ensure that all goats responded equally to varying dosages of cloprostenol (Clo.) without considering the stage of the oestrous cycle, 25 goats were injected (treatment A) between days 11 and 14 of the oestrous cycle with 125 μg Clo./goat intramuscularly (IM). At the time of the second injection, given 11 days later, five different treatments (treatment B), consisting of 125 μg Clo.IM, 125 μg Clo. IVSM, 62.5 μg Clo. IVSM, 31.25 μg Clo. IVSM and saline IM, were given to groups 1, 2, 3, 4 and 5, respectively. Oestrus was monitored by teaser bucks. Blood samples taken at the time of treatment B and daily for 6 days thereafter were assayed for progesterone to confirm that luteolysis had occurred as expected. All goats in groups 1, 2 and 3, and one out of five in group 4 exhibited oestrus within 68 h of treatment B. Serum progesterone levels exhibited values below 1 ng/ml within 24 h of treatment B in groups 1, 2 and 3 and decreased to nadir levels within 48 h of treatment B. Lack of luteolysis in goats of groups 4 and 5, as shown by progesterone concentrations, was the reason for failure of synchronization in these groups. It is concluded that a small dose of cloprostenol given by intravulvo-submucosa injection is effective in inducing oestrus in dioestrous cycling goats.     

Reproductive performance of dairy cows following treatment with cloprostenol 26 and/or 40 days postpartum: a field trial

One hundred and seventy Holstein Friesian cows were randomly assigned to receive either 500 ug cloprostenol or saline placebo on Day 26 postpartum followed by 500 ug cloprostenol or saline on Day 40 postpartum. Four treatment groups were formed: Group 1 - saline (Day 26)/saline (Day 40); Group 2 - cloprostenol/(Day 26) saline (Day 40); Group 3 - saline (Day 26)/cloprostenol (Day 40); Group 4 - cloprostenol (Day 26)/cloprostenol (Day 40). Double blind techniques were used in administering treatments and in assessing the response to treatment. Palpation of the reproductive tract per tectum and uterine biopsies were performed on 92 cows prior to each treatment at Day 26 and Day 40 postpartum. Progesterone concentrations were determined on milk samples collected prior to treatment. There were no significant differences among treatment groups with respect to services per conception, number of heats detected before first service and culling for infertility. Cloprostenol treatment at Day 26 appeared to delay the first estrus, but it reduced the number of days to conception after the first service. Cows receiving cloprostenol at Days 26 and/or 40 had a decreased calving-to-conception interval compared to controls (P = 0.01). Sequential therapy with two doses of cloprostenol resulted in slightly better reproductive performance than either treatment on Day 26 or 40 alone. Treatment with cloprostenol resulted in a decrease in the subsequent incidence of pyometra (P < 0.05). It is concluded that in the herd studied, cloprostenol therapy at Day 26 and/or 40 postpartum was beneficial to reproductive performance. Although it was anticipated that cloprostenol would be more effective in cows with elevated progesterone levels, the opposite was observed at the Day 26 cloprostenol treatment. Uterine biopsy at Days 26 and/or 40 had a detrimental effect on subsequent reproductive performance.     

Effects of dose and route of administration of cloprostenol on luteolysis,estrus and ovulation in beef heifers

Four experiments were conducted (with crossbred beef heifers) to determine the effects of dose and route of administration of cloprostenol on luteolysis, estrus and ovulation. In Experiment 1, 19 heifers with a CL > or = 17 mm in diameter were randomly allocated to receive cloprostenol as follows: 100 microg s.c., 250 microg s.c., or 500 microg i.m. Heifers given 100 microg s.c. had a longer (P<0.03) interval (120.0 h+/-10.7 h; mean+/-S.E.M.) from treatment to ovulation than those given either 250 microg s.c. or 500 microg i.m. (92.0 h+/-7.4 h and 84.0 h+/-8.2 h, respectively). In Experiment 2, 28 heifers were given porcine LH (pLH), followed in 7 days by cloprostenol (same doses and routes as in Experiment 1), and a second dose of pLH 48 h after cloprostenol. Luteolysis occurred in all heifers, and no difference was detected among treatment groups in the interval from cloprostenol treatment to ovulation (mean, 101 h; P<0.9). In Experiment 3, 38 heifers at random stages of the estrous cycle (but with plasma progesterone concentrations > or =1.0 ng/ml) received 500 or 125 microg cloprostenol by either i.m. or s.c. injection (2/2 factorial design). There was no difference (P<0.4) among groups in the proportions of heifers that were detected in estrus or that ovulated. However, the interval from cloprostenol treatment to estrus was shorter (P<0.02) in the group that received 500 microg i.m. (58.5h) than in the other three groups (500 microg s.c., 75.0 h; 125 microg i.m., 78.0 h; and 125 microg s.c., 82.3h). In Experiment 4, 36 heifers were treated (as in Experiment 3) on Day 7 after ovulation. The proportions of heifers detected in estrus and ovulating after 125 microg s.c. (33 and 44%, respectively) or 125 microg i.m. (55 and 55%) were lower (P<0.05) than in those that received 500 microg s.c. (100 and 100%), but not different from those receiving 500 microg i.m. (78 and 89%, respectively). Overall, ovulation was detected in 9/18 heifers given 125 microg and 17/18 heifers given 500 microg of cloprostenol, on Day 7 (P<0.01) and was detected in 17/20 heifers given 125 microg and 18/18 heifers given 500 microg of cloprostenol, at random stages of the estrous cycle (P>0.05). Although there was no significant difference in luteolytic efficacy between i.m. and s.c. injections of the recommended dose (500 microg) of cloprostenol, variability in responsiveness to a reduced dose depended upon CL sensitivity, therefore, reduced doses cannot be recommended for routine use.     

The effects of different PMSG doses on estrus behavior and pregnancy rate in Angora goats

Artificial insemination protocols depend on efficient behavioral estrus detection and insemination time in Angora goat. Therefore, we aim to determine the accuracy of an estrus scoring system in Angora goats with different PMSG doses during the breeding season. Does (n: 260) were randomly divided into three groups: group-1 (n: 93), group-2 (n: 85) and group-3 (n: 82). All animals received an intravaginal sponge on day 0 for 11 days, and on the day of sponge insertion 150 μg prostaglandin F2Α was administered. Pregnant mare’s serum gonadotropin was injected 300, 400 and 500 IU intramuscularly 24 h before sponge removal to groups 1, 2 and 3, respectively. Estrus signs were detected with a teaser buck, 24 h after sponge removal according to a visual scoring system. Artificial insemination was performed with 0.25 ml fresh diluted semen at 43 to 45 h after sponge removal. Differences were observed within PMSG groups in terms of standing, tail wagging, courtship behavior, vaginal discharge and vaginal hyperemia (P<0.001). Nevertheless, the most accurate indicators of estrus that result in pregnancy were tail wagging and courtship behavior followed by standing estrus (P<0.05). According to the results obtained, 300 IU PMSG dose is sufficient, both to inseminate at a fixed time (43 to 45 h after sponge removal) and to record the estrus behavior by teaser male 24 h after sponge removal. Higher PMSG doses (400 to 500 IU) altered the timing of ovulation; specifically, 500 IU dose shortened the duration of estrus behaviors. In conclusion, even though the different doses of PMSG displayed similar effects on estrus synchronization and pregnancy rates, we concluded that tail wagging, courtship behavior and standing heat are the most reliable estrus signs for artificial insemination in Angora goat.     

Effect of service on estrus duration in dairy goats

The objective of this research was to determine the effect of sterile service on estrus duration in multiparous and nulliparous dairy goats. Twenty Nubian goats (10 multiparous and 10 nulliparous) were randomly assigned to of 4 treatment groups (n = 5 animals per group). Group MNS, multiparous without service; Group MS, multiparous with service; Group NNS, nulliparous without service and Group NS, nulliparous with service. Estrus was synchronized by utilization of fluorogestone acetate intravaginal pessaries (40 mg.) over a 12-day period plus 250 IU, i.m. of pregnant mare serum gonadotropin (PMSG) at pessary removal. Estrus was detected with the aid of a vasectomized buck for 5 days after pessary removal for 6-hour intervals (0600, 1200, 1800 and 2400 hours). In the groups that were not serviced the teaser was equipped with an apron and was only allowed to mount. In the serviced groups, the teaser was permitted to mount and service each female on 2 occasions during the first 12 hours of estrus. Estrus initiation for Groups NNS, NS, MNS and MS were (mean +/- SD) 61.5 +/- 29.5, 61.2 +/- 35.4, 63.0 +/- 22.2 and 69.6 +/- 32.5 hours, respectively (P>0.05). Estrus duration for the same groups were (mean +/- SD) 42.0 +/- 12.0, 30.0 +/- 6.0, 42.0 +/- 7.3 and 28.8 +/- 10.7 hours, respectively. These results show that estrus duration was shortened by serving (P<0.01), and that there were no differences between multiparous and nulliparous goats with or without serving (P>0.05). It is concluded that estrus duration in goats is shortened by serving and that no differences in duration exist between multiparous and nulliparous.     

Uterine motility in the cow during the estrous cycle. II. Comparative effects of prostaglandins F(2alpha), E(2), and cloprostenol

Intrauterine pressure (IUP) changes were recorded in nonlactating, cyclic dairy cows using transcervically placed intraluminal pressure microtransducers. Spontaneous activity was recorded for the first 30 min. Prostaglandins (PG) F(2alpha) (5 mug/kg), E(2) (5 mug/kg), or cloprostenol (0.1 mug/kg) were then injected intravenously (i.v.) at diestrus, proestrus, estrus, and metestrus, and their effects were recorded. The drug administrations did not alter the duration of the estrous cycle of the cows. Single doses of PGF(2alpha) and E(2) significantly increased uterine activity at all stages of the estrous cycle, while cloprostenol had no effect. PGF(2alpha) and PGE(2) increased IUP, frequency, and amplitude during all stages of the estrous cycle. The spontaneous pattern resumed within 20 min postinjection. Partial uterine refractoriness occurred with both PGs. The results indicate that low doses of natural prostaglandins stimulate uterine activity during the estrous cycle in cattle.     

Synchronization of estrus and fertility in goats with norgestomet ear implants

Estrus was synchronized in 64 dairy goats in July with norgestomet ear implants. Half the does received ear implants that contained 6 mg norgestomet and the remaining does received implants that contained 3 mg. Implants were left in place for 11 days. Each doe received i.m. injections of 400 IU PMSG and 50 mug cloprostenol 24 hours prior to implant removal. Twenty-eight of 32 does (87.5%) that received 6 mg or 3 mg norgestomet exhibited onset of estrus within 24 hours of implant removal. All does had exhibited onset of standing estrus by 43 hours after implant removal. Does were hand-mated to fertile bucks twice daily while in standing estrus. There were no differences between does implanted with 6 mg or 3 mg in fertility to the induced estrus (74.2% vs 75% kidding), mean length of gestation (151.0 +/- 3.2 vs 151.6 +/- 2.0 days), mean number of kids per doe (2.1 +/- 0.8 vs 2.3 +/- 0.7) or in mean kid weights (3.10 +/- 0.80 vs 3.06 +/- 0.86 kg) (6 mg vs 3 mg, respectively). It was concluded that ear implants that contained 3 mg of norgestomet were equally as effective as implants that contained 6 mg for synchronization of estrus in dairy goats.     

New estrus synchronization and artificial insemination protocol for goats based on male exposure, progesterone and cloprostenol during the non-breeding season

This study assesses the effectiveness of a method designed to induce and synchronize ovulation in goats during the non-breeding season, allowing for systematic timed artificial insemination (AI), without the need for prior estrus detection. This method (IMA.PRO2) induces ovulation through the "male effect" and a single 25 mg dose of progesterone given at the time of buck exposure, and early lysis of the induced corpus luteum by the administration of 75 microg of cloprostenol 9 days later. The method was tested in three separate experiments. In experiment 1, estrus was detected in 87.5% of the treated goats 37.0 +/- 1.4 h after cloprostenol administration, with the preovulatory LH surge occurring 40.5 +/- 1.6 h after the cloprostenol injection. In experiment 2, data from 503 does revealed no significant differences in fertility rates between two groups inseminated 48 h (65.5+/-4.0%) or 52 h (63+/-3.0%) after receiving cloprostenol. In experiment 3, 2184 does, comprising 37 replicate groups on 12 farms, were randomly assigned to two trial subgroups. Does in the first subgroup were treated with the IMA.PRO2 method and goats from the second group were given intravaginal progestagens for 11 days, plus 350 IU of eCG and 75 microg of cloprostenol on Day 9 of this treatment. Goats from both subgroups were cervically inseminated at the same time, 50 h after cloprostenol administration in the first group and 46 h after sponge removal in the second. The pregnancy rate achieved with the new method was 64.6%, significantly higher than the yield observed for the use of progestagens plus eCG (46.8%, P<0.01). The simple method proposed as an alternative to the use of progestagen-eCG treatment provides good pregnancy rates to AI undertaken at a fixed time point, and reduces the amount of hormone needed to synchronize estrus in the animals.     

Superovulation in the cow using estradiol 17beta or GnRH in conjunction with FSH-P

A study was designed to evaluate the superovulatory response in the cow when either estradiol 17beta or gonadotrophin releasing hormone (GnRH) was used in a superovulatory regimen with follicle stimulating hormone (FSH-P). Fifty-four cyclic crossbred females were superovulated in replicates between Days 8 and 12 of their cycle. All animals were treated with 28 mg of FSH-P in twice-daily decreasing doses, each receiving 500 mug cloprostenol (PGF) 48 h after initiation of treatment. Group 1 served as FSH-P controls, Group 2 received FSH-P and 400 mug of estradiol 17beta 36 h after PGF, and Group 3 received FSH-P and 250 mug GnRH 48 h after PGF. Inseminations with one vial of frozen semen were done at 12, 24 and 36 h after the onset of estrus. Ova/embryos were collected nonsurgically at Day 7 postestrus. Numbers of corpora lutea (CL) were recorded after palpation per rectum and the recovered ova and embryos were evaluated. All females were bled for endocrine examination. There were no differences in ovarian response among these treatments. Mean total ova/embryos collected in Group 3 was significantly higher than in Groups 1 or 2 (P < 0.05); however, no significant difference existed between groups in the mean numbers of fertilized or transferable embryos. Similarly, no significant differences existed between groups for recovery rate, fertilization rate, or percentage of transferable embryos. Serum estradiol levels were significantly higher at the expected end of ovulation in Group 2, and this tended to be associated with higher fertilization and transferable embryo rates. Furthermore, a significant positive correlation was found to exist between CL numbers and each of the ova/embryo parameters and the estradiol levels at estrus.     

Synchronization of estrus and fertility in beef cattle with two injections of buserelin and prostaglandin

Postpartum beef cows and heifers in Group 1 received 8 mug of buserelin on Day 0 (the beginning of the experiment) and 500 mug of cloprostenol (PGF) on Day 6 (GnRH I, n = 54). In Group 2 (GnRH II, n = 54), the females were injected with buserelin on Day 0 (8 mug) and Day 3 (4 mug), and PGF on Day 6 and Day 9 for females not detected in estrus previously. Animals were bred by AI 12 hours after the onset of estrus. Blood samples were collected on Day -11 and Day 0 to assess cyclicity and on Day 3 and Days 6 to 12 to examine luteal activity. Progesterone levels did not differ between the 2 groups between Days 0 to 9. In both groups, the proportion of spontaneous estruses from Days 0 to 6 was reduced. Precision of estrus was higher (P < 0.005) in the GnRH II group than in the GnRH I group of cows that were detected in estrus between Days 6 and 9. The synchronization rate, interval to estrus, pregnancy and conception rates were similar in GnRH I and GnRH II groups. The conception rate and interval to estrus were similar in cyclic and acyclic cows. Increasing the number of buserelin injections enhanced the precision of estrus, but not the conception rate, without any detrimental effect on luteal activity and induced more estruses in postpartum acyclic beef cattle.     

Use of Chronogest implants and Folltropin for estrus synchronization and superovulation in goats.

Six Barbari goats each were assigned randomly to treatments 1,2 or 3, comprising im injections of FSH (folltropin) at 12, 14 or 16 mg dose level respectively. Estrus was synchronized with intravaginal sponge impregnated with flugestone acetate (30 mg; chronogest) inserted for 12 days and cloprostenol (125 micrograms) im at the insertion as well as at removal of sponge. FSH treatment started 48 hr before the sponge removal as 4-day declining dose scheme. Estrus could be effectively synchronized in all goats under the study, with significant difference (P less than 0.05) in the onset of estrus between the treatment groups. All goats were administered with 750 IU hCG i.v. at estrus. Recording of ovarian response and embryo recovery was done 45 hr after the onset of estrus. The prime aim of superovulation was effectively achieved in Barbari goats with the use of chronogest implants and folltropin. There was no difference (P greater than 0.05) between the treatment groups in recovery of transferable embryos, however, 14 mg folltropin appeared to be near optimal dose. There was no adverse effect on the quality of recovered embryos with high doses of folltropin.     

Induction and synchronization of estrus in goats: the relative efficiency of one versus two fluorogestone acetate-impregnated vaginal sponges

The purpose of the experiment was to test the hypothesis that a variable and/or insufficient level of progestagen at the end of a treatment to synchronize estrus in goats could explain variability in the onset of estrus. The experiment was performed during the anestrous season on 2 herds, one of Alpine (n = 49) the other of Saanen (n = 53) dairy goats. The animals were allocated to 1 of 3 treatments: Group 1 received a vaginal sponge impregnated with 45 mg of fluorogestone acetate (FGA) on Day 0; Group 2 received a sponge on Day 0 plus a second sponge on Day 7; Group 3 received a sponge on Day 0 plus a second sponge on Day 9. The sponges were withdrawn on Day 11. All goats received 400 or 500 IU eCG and 50 mug PGF(2alpha) analog 48 h prior to sponge removal. They were inseminated with frozen-thawed semen 24 h after the onset of estrus. Among treatment groups no difference (P > 0.05) was observed for the following parameters: percentage of goats in estrus, percentage of goats ovulating, mean time and variability of onset of estrus. The fertility of Alpine goats in Group 3 was significantly decreased (P < 0.05). No effect on prolificacy was noticed. These observations show that to increase progestagen level at the end of treatment did not improve estrus synchronization. They provide further evidence that treatments with too high progestagen amounts can decrease fertility.     

Reproductive performance of dairy cows following treatment with fenprostalene, dinoprost, or cloprostenol between 24 and 31 Days post partum: a field trial

Three hundred and one Holstein cows (n=301), calving at a commercial free-stall dairy farm, were randomly assigned to 1 of 3 prostaglandin treatment groups or a placebo group. The placebos were packaged 3 ways to mimic the 3 commercial prostaglandin preparations. Group 1 received 1 mg fenprostalene and 1.6 mg oxytetracycline; Group 2 received the fenprostalene placebo (2 ml polyethylene glycol and 1.6 mg oxytetracycline); while Group 3 was given 25 mg dinoprost. Group 4, the dinoprost placebo received 5 ml saline; Group 5 received 500 ug cloprostenol; and Group 6 the cloprostenol placebo received 2 ml saline. The treatments were administered between Days 24 and 31 post partum. Double blind techniques were used in administering treatments and in assessing the response to treatment. There were no significant differences among treatment groups with respect to incidence of retained fetal membranes, endometritis, pyometra, anestrus, number of services per pregnancy, calving-to-first estrus interval, services per conception, number of prostaglandin treatments other than those administered between Days 24 and 31 post partum, the percentage culled for reproductive reasons and all factors combined. Cows receiving fenprostalene, dinoprost or cloprostenol had a decreased calving-to-conception interval compared with that of the controls (P = 0.05). It is concluded that, in the herd studied, treatment with any of the 3 commercially available prostaglandin products between Days 24 and 31 post partum was beneficial for reproductive performance.     

Effects of estradiol-17β and hCG supplementation on superovulatory responses and embryo quality in swamp buffalo (Bubalus bubalis) implanted with norgestomet

Twenty-four cycling swamp buffaloes with normal reproductive histories and 2–3 months postpartum were used to investigate the effect of addition of estradiol-17β and human chorionic gonadotrophin (hCG) to the superovulation regime on the level of ovarian stimulation and embryo production.The estrous cycles of buffaloes were synchronized by prostaglandin injection and then divided into two groups for superovulatory treatment. Those in Group 1 (n = 12) received a implant containing 3 mg norgestomet (Syncro-Mate-B) for 9 days (insertion day is Day 0), with 4000 IU of equine chorionic gonadotrophin (eCG) and 500 μg cloprostenol i.m. given at Day 7. Group 2 (n = 12) received the same regime as Group 1, together with 7.5 mg estradiol-17β given in three intramuscular injections on Days 3, 5 and 7 in decreasing doses (4.0, 2.5 and 1.0 mg, respectively) and 5000 I.U hCG i.v. coincidentally with the first insemination. Estrus was monitored visually and by placing treated animals with bulls. Each animal was inseminated twice with frozen sperm after standing estrus. The numbers of corpora lutea (CL) and follicles greater than 8 mm in diameter were recorded via palpation per rectum at 6 days after implant removal. Two days later 11 animals from Group 2 and two from Group 1 were slaughtered for direct observation of ovarian responses and for embryo collection.The mean number of CL were 0.91 ± 0.66 and 9.08 ± 5.0 for Groups 1 and 2, respectively. The average recovery rate based on CL counts at slaughter was 60% in Group 2. No embryos were recovered from the two animals in Group 1. Seventy-nine percent of the collected ova were fertilized and more than 60% of them had developed into hatched blastocysts. The percentages of buffalo with excellent and good estrus were 41.6 and 91.6% for Groups 1 and 2, respectively.These results showed that the supplementation of estradiol-17β and the hCG treatment significantly improved the level of ovarian stimulation in swamp buffalo.     

Effect of service number on estrus duration in dairy goats

The object of this research was to study the effect of sterile service number on estrus duration in dairy goats. Twenty-four Nubian goats (20 nulliparous and 4 multiparous) were randomly assigned to 1 of 4 treatment groups (n = 6 animals per group). The following Groups were formed: no service (GS-0); 1 service (GS-1); 2 services (GS-2); 3 services (GS-3). Estrus was synchronized by using fluorogestone acetate intravaginal pessaries (40 mg) over a 12-d period plus 400 IU im pregnant mare serum gonadotropin (PMSG) at pessary removal. Estrus was detected by using a vasectomized buck at 6-h intervals over 5 d after pessary removal (at 0600, 1200, 1800 and 2400 h). In the GS-0 group the teaser was outfitted with an apron and was permitted to mount. In the GS-1, GS-2 and GS-3 groups, the teaser was permitted to mount and service 1, 2 and 3 times, respectively, within the first 12 h after initiation of estrus. The duration of estrus for the 4 groups (GS-0, GS-1, GS-2 and GS-3) was (mean +/- SD) 41.0 +/- 5.9, 24.0 +/- 5.4, 22.0 +/- 4.9 and 22.0 +/- 7.2 h, respectively. These results show differences between the serviced groups and the nonserviced group (P<0.01), but they fail to show differences among the serviced groups (P>0.05). It is concluded that sterile service shortens estrus duration and that service number (1, 2 or 3) does not affect estrus duration.     

Influence of GnRH administration on timing of the LH surge and ovulation in dwarf goats

This study was conducted to determine whether or not exogenous gonadotropin releasing hormone (GnRH) alters the timing or improves the synchrony of estrus, the LH surge, and ovulation following estrous synchronization in dwarf goats, and to assess the effects of season on these parameters. In January and June, estrus was synchronized in 12 Pygmy and Nigerian Dwarf goats with a 10-day progestagen sponge, 125 microg cloprostenol i.m. 48 h before sponge removal, and 300 IU equine chorionic gonadotrophin (eCG) i.m. at sponge removal. Six of the 12 goats were given 50 microg GnRH i.m. 24h after sponge removal. Onset of estrus was monitored using two males. Samples for plasma LH were collected at 2 h intervals beginning 22 h after sponge removal and ending at 48 h in January and at 58 h in June. Time of ovulation time was confirmed by laparoscopy at 36, 50, 60, and 74 h in January and at 50, 60, and 74 h in June. Administration of GnRH had no significant effect on the onset of estrus; however, it reduced the interval from sponge removal to the LH surge and improved the synchrony of the LH surge (P<0.05). Treatment with GnRH also reduced the interval from sponge removal to ovulation and improved the synchrony of ovulation (P<0.05). Season had a significant effect on the timing and the synchrony of estrus with and without GnRH treatment (P<0.05). A seasonal shift was also observed in the timing of the LH surge in the absence of GnRH treatment (P<0.05). Further research is required to determine the optimum time for GnRH administration and the minimum effective dose in dwarf goats.