Ovulation rate, zygote recovery and follicular populations in FSH-superovulated goats treated with PGF(2alpha) and/or GnRH

Follicular development and ovulation were examined in superovulated Nubian and Nubian-cross dairy goats following prostaglandin F(2alpha) (PGF(2alpha)) and/or gonadotropin releasing hormone (GnRH) treatment. Estrus was synchronized with Synchromate-B((R)) implants. Superovulation was induced with follicle stimulating hormone (FSH) and augmented with GnRH and/or PGF(2alpha). The PGF(2alpha) treatment was administered on Day 2 of superovulation. Implants were removed from all goats on Day 3 of superovulation. The GnRH treatment was administered 24 h after implant removal. All does were exposed to fertile males for 48 h at the time of GnRH injection. Surgical embryo recovery and ovarian response evaluation were conducted 64 to 78.5 h after implant removal. The number of ovulations was higher with GnRH treatment (18.5 +/- 7; x +/- SEM) than that in the controls (5.3 +/- 4.1; P < 0.05). There were fewer follicles in the GnRH-treated does than in the untreated does (10.9 +/- 2.9 vs 22.1 +/- 3.2; P < 0.05). The number of follicles smaller than 4 mm in diameter (5.8 +/- 0.8) did not differ between treatments. The GnRH-treated does had fewer 4- to 8-mm follicles (4.2 +/- 2.0 vs 9.1 +/- 1.6; P < 0.05) and fewer follicles larger than 8 mm (0.7 +/- 1.4 vs 7.3 +/- 1.6; P < 0.01) than the controls. Predicted times for 1- and 2-cell embryo recoveries were 68.5 and 73.7 h following implant removal, respectively. This study demonstrates that GnRH is an effective supplement used with FSH superovulation regimens in dairy goats. Moreover, GnRH provides for enhanced early embryo collection for DNA microinjection studies.     

Effect of fluorogestone acetate on embryo recovery and quality in eCG-superovulated goats with premature luteal regression

The objective of this study was to evaluate if treatment of eCG-superovulated goats with fluorogestone acetate (FGA) would increase the number and quality of embryos recovered. Goats (n = 25) were given an intravaginal sponge containing 45 mg FGA for 12 days, with 1000 IU eCG and 7.5mg of Luprostiol (a PGF(2 alpha) analog) given -48 and 0 h relative to sponge removal. Goats were mated by natural service every 12h during estrus and surgical embryo collection was done 6 days after the last mating. There were two treatment groups; those in the FGA group (n = 13) had a FGA sponge from 8h after mating to embryo collection, whereas goats in the control group (n = 12) did not receive any post-mating treatment. Premature luteal regression occurred in 61.5% (8/13) and 83.3% (10/12) of the goats in the FGA and the control groups, respectively (P > 0.05). Corpus luteum life span averaged 4 days in goats with premature luteolysis. The mean (+/- S.E.) number of transferable embryos was 5.7 +/- 1.6 in the FGA group and 0.1 +/- 0.1 in the control group (P < 0.05). Within the FGA group, the embryo recovery rate was similar in goats with premature luteal regression compared to those with normal luteal function, although non-transferable embryos were only found in goats with premature luteal regression. In conclusion, post-breeding treatment with FGA increased embryonic survival in eCG-superovulated goats, even though it did not prevent premature luteal regression.     

Superovulation of dairy cows with purified FSH supplemented with defined amounts of LH

This study investigated the effects of a purified follicle stimulating hormone (FSH) preparation supplemented with three different amounts of bovine luteinizing hormone (bLH) and a commercially available FSH with a high LH contamination on superovulatory response, plasma LH and milk progesterone levels in dairy cows. A total of 112 lactating Holstein-Friesian crossbred dairy cows were used for these experiments; the cows were randomly assigned to treatment groups consisting of purified porcine FSH (pFSH) supplemented with bLH. Group 1 was given 0.052 IU LH 40 mg armour units (AU) FSH (n = 6); Group 2 was given 0.069 IU LH (n = 32); Group 3 received 0.423 IU LH (n = 34); while Group 4 cows (n = 36) were superovulated with a commercially available FSH-P((R)). This compound appeared to contain 8.5 IU LH 40 mg AU FSH according to bioassay measurement. All animals received a total of 40 mg AU FSH at a constant dose twice daily over a 4-d period. Levels of milk progesterone and plasma LH were determined during the course of superovulatory treatment. The Group 1 treatment did not reveal multiple follicular growth, and no embryos were obtained. Superovulation of Group 3 cows resulted in significantly (P<0.05) more corpora lutea (CL; 12.6+/-1.1) and fertilized ova (5.1+/-1.3) compared with Groups 2 and 4 (10.1+/-0.9 and 2.6+/-0.6, 9.0+/-0.9 and 2.7+/-0.5, respectively). Due to a high percentage of degenerated embryos (33%) Group 3 yielded only one more transferable embryo than Groups 2 and 4. Among groups, LH levels differed in the period prior to induction of luteolysis and were similar thereafter. The progesterone pattern following FSH LH administration reflected the amount of LH supplementation. Milk progesterone levels on the day prior to embryo collection were correlated to the number of CLs and recovered embryos. It is concluded that under the conditions of our experiment superovulation with 0.423 IU LH 40 mg AU FSH may yield a significantly improved superovulatory response in dairy cows. It is further suggested that LH supplementation exerts its effects mainly on follicular and oocyte maturation during the period prior to luteolysis.     

Fertility responses and hormonal profiles in repeat breeding cows treated with insulin

The influence of insulin treatment on conception rate and endocrine profile was studied on 21 repeat breeding cows divided randomly into two groups, i.e. insulin treatment (n = 11) and control (n = 10). Cows of the insulin treatment group were injected subcutaneously with a long acting purified form of bovine insulin at 0.2 IU/kg body weight/day on days 8, 9 and 10, and then with 0.75 mg tiaprost (PGF(2)alpha) intramuscularly on day 12 of the oestrous cycle (oestrus = day 0). The cows of the control group only received 0.75 mg tiaprost was injected intramuscularly on day 12. There was no difference (P > 0.05) in the interval to the onset of oestrus and subsequent cycle length between the treatment (84.5 +/- 6.6 h and 21.2 +/- 0.6 days, respectively) and the control (72.3 +/- 5.9 h and 19.7 +/- 0.4 days, respectively) groups. First service conception rate and overall pregnancy rate did not differ (P > 0.05) between the insulin treatment group (45.4 and 63.6%) and the control group (33.3 and 40.0%). Progesterone concentration following administration of insulin increased (P < 0.05) in the insulin treated cows (2.2+/-0.4 ng/ml versus 2.9 +/- 0.4 ng/ml) but the concentration of oestradiol-17beta did not differ. The insulin concentration was higher on day 10 of the oestrous cycle (P < 0.05) in the treatment group (71.0 +/- 12.5 microU/ml versus 38.1 +/- 4.5 microU/ml). The insulin and glucose concentrations were higher (P > 0.05) in animals, which subsequently became pregnant than in non-pregnant animals. The results may indicate that there is beneficial effect of insulin on fertility in repeat breeder cattle.     

Follicular growth, ovulation and embryo recovery in dairy cows given FSH at the beginning or middle of the estrous cycle

Variability in the superovulation response is an important problem for the embryo transfer industry. The objective of this study was to determine whether FSH treatment at the beginning of the cycle would improve the ovulation rate and embryo yield in dairy cows. Twenty-eight postpartum cyclic dairy cows were allocated at random to 4 treatment groups (A, B, C and D). Group A cows (n = 10) received FSH (35 mg) at a decreasing dose, starting on Day 9 (Day 0 = day of estrus) for 5 days followed by PGF(2alpha) (35 mg) on Day 12. Cows assigned to Groups B, C and D (n = 6 cows each, respectively) were given 35 mg FSH at a decreasing dose from Days 2 to 6 followed by PGF(2alpha) on Day 7. Group C and D cows received PRID inserts from Day 3 to Day 7. Cows in Group D additionally received 1000 IU hCG 60 hours after PGF(2alpha) treatment. Ovaries were scanned daily using a real time ultrasound scanner from the beginning of FSH treatment until embryo recovery, to monitor follicular development, ovulation and the number of unovulated follicles. Embryos were recovered from the uterus by a nonsurgical flushing technique 7 days after breeding. There were no differences (P>0.01) in the number of follicles > 10 mm at 48 hours after PGF(2alpha) treatment among the 4 groups. The mean numbers of follicles were 10.6 +/- 1.2, 9.3 +/- 1.3, 12.2 +/- 1.3 and 15.0 +/- 2.9 for Groups A, B, C and D, respectively. A significantly (P<0.001) higher number of ovulations was observed and a larger number of embryos was recovered in Group A than in the other groups. The results of this study indicate that superovulation with FSH at the beginning of the cycle causes sufficient follicular development but results in very low ovulation and embryo recovery rates.     

Prostaglandin E2 counteracts the effects of PGF2 alpha in indomethacin treated cycling gilts

Twenty crossbred gilts with at least 2 consecutive estrous cycles of 18 to 21 days in length were used to study the effects of prostaglandins E2 and F2 alpha (PGE2 and PGF2 alpha) on luteal function in indomethacin (INDO) treated cycling gilts. Intrauterine and jugular vein catheters were surgically placed before day 7 of the treatment estrous cycle and gilts were randomly assigned to 1 of 5 treatment groups (4/group). With exception of the controls (Group I) all gilts received 3.3 mg/kg INDO every 8 h, Groups III, IV and V received 2.5 mg PGF2; 2.5 mg PGF2 alpha + 400 micrograms PGE2 every 4 hr, or 400 micrograms PGE2 every 4 h, respectively. All treatments were initiated on day 7 and continued until estrus or day 23. Jugular blood for progesterone analysis was collected twice daily from day 7 to 30. Estradiol-17 beta (E2-17 beta) concentrations were determined in samples collected twice daily, from 2 d before until 2 d following the day of estrus onset. When compared to pretreatment values, estrous cycle length was unaffected (P greater than 0.05) in Group I, prolonged (P less than 0.05) in Groups II, IV and V; and shortened (P less than 0.05) in Group III. The decline in plasma progesterone concentration that normally occurs around day 15 was unaffected (P greater than .05) in Group I; delayed (P less than 0.05) in Groups II, IV and V; and occurred early (P less than 0.05) in Group III. Mean E2-17 beta remained high (31.2 +/- 4.9 to 49.3 +/- 3.1 pg/ml) in Groups III and IV, while the mean concentrations in Groups III and V varied considerably (17.0 +/- 2.0 to 52.2 +/- 3.5 pg/ml). The results of this study have shown that PGE2 will counteract the effects of PGF2 alpha in INDO treated cycling gilts. The inclusion of PGF2 alpha appeared to either stimulate E2-17 beta secretion or maintain it at a higher level than other treatments.     

Ovarian activity in progesterone treated mares following administration of pregnant mare serum gonadotropin

Twelve non-pregnant, non-lactating mares were randomly assigned to four treatment groups using a 2x2 factorial arrangement with three replicates per group. Mares were administered PGF(2alpha) (10 mg, IM) on days -14 and 0, followed by HCG (3000 IU, IM) on day 5. The following treatments were administered: Group A received PMSG on days 2 (4000 IU, IM) and 5 (1000 IU, IV); Group B received PMSG (4000 IU, IM) on day 2; Group C received PMSG (1000 IU, IV) on day; Group D received no PMSG. Mares received progesterone (25 mg, IM) on days 1 through 4. Reproductive tracts were recovered at necropsy on day 16 (10 days post-ovulation). Ovaries were weighed, CL number and weight determined, follicles counted and measured, and volume of follicular fluid quantified. Mean ovarian weight (g) and number of CL per mare, respectively were: Group A, 100.0+/-15.6, 1.7+/-.7; Group B, 128.6+/-40.4, 1.3+/-.7; Group C, 92.4+/-21.0, 2.0+/-.0; Group D, 93.3+/-12.3; .3+/-.3. Mean number of follicles >10 mm and total volume (ml) of follicular fluid per mare, respectively, were: Group A, 9.4+/-2.0, 21.8+/-10.9; Group B, 1.3+/-.3, 32.2+/-28.9; Group C, 4.3+/-1.8, 5.4+/-2.3; Group D, 6.0+/-4.5, 24.0+/-10.3. There was no difference (P>.05) in mean ovarian weight, CL number, CL weight, follicular fluid volume, number of follicles, or size of follicles between treatment groups. These results show no significant effect on ovarian activity in progesterone treated mares following administration of exogenous PMSG.     

Restoration of endocrine and ovarian function after stopping GnRH antagonist treatment in goats

We have tested if the high number of unfertilized ova and degenerated embryos found in superovulated goats previously treated with GnRH antagonist can be related to a prolongation of gonadotrophin down-regulation and/or alterations in follicular function during the period of administration of the superovulatory treatment, around 4 days after the end of the antagonist treatment. A total of 15 does were treated with intravaginal progestagen sponges and daily injections of 0.5mg of the GnRH antagonist Antarelix for 6 days, while 5 does acted as controls receiving saline. During the antagonist treatment, the mean plasma LH concentration was lower in treated than control goats (0.5 +/- 0.2 versus 0.7 +/- 0.5 ng/ml, P < 0.0005 ); however, the FSH levels remained unaffected (0.8 +/- 0.4 versus 0.8 +/- 0.5 ng/ml). In this period, treated does also showed an increase in the number of small follicles with 2-3 mm in size ( 10.7 +/- 0.7 versus 8.4 +/- 0.6, P < 0.05), and a decrease in both the number of follicles > or =4 mm in size ( 5.0 +/- 0.3 versus 6.8 +/- 0.5, P < 0.005) and the secretion of inhibin A (120.9 +/- 10.7 versus 151.6 +/- 12.6 pg/ml, P < 0.05). After cessation of the antagonist treatment, there was an increase in LH levels in treated goats from the day after the last Antarelix injection (Day 1), so that LH levels were the same as controls on Day 3 (0.6 +/- 0.1 versus 0.6 +/- 0.2 ng/ml). However, there were even greater numbers of small follicles than during the period of antagonist injections (15.4 +/- 0.6 in treated versus 8.9 +/- 0.7 in control, P < 0.0005 ). Moreover, the number of > or =4 mm follicles and the secretion of inhibin A remained lower in treated goats (3.9 +/- 0.3 follicles and 84.4 +/- 7.0 pg/ml versus 5.4 +/- 0.5 follicles, P < 0.05 and 128.9 +/- 14.2 pg/ml, P < 0.05 ). These results indicate that pituitary secretion of gonadotrophins is restored shortly after the end of antagonist treatment, but activity of ovarian follicles is affected.     

Regulation of in vitro progesterone release from caprine luteal tissues by prostaglandins E2 and F2a

Luteal slices obtained from Day-10 cyclic, sexually mature, mixed-breed, superovulated goats were used to study the effects of prostaglandins E(2) and F(2)a (PGE(2) and PGF(2)a) on the release of progesterone. The goats were synchronized for estrus using a single intramuscular injection of 5 mg PGF(2)a given during the mid-luteal phase of the estrous cycle. Multiple follicular growth and superovulation were induced using a treatment regiment of follicle stimulating hormone (FSH) and luteinizing hormone releasing hormone (LHRH) previously standardized in our laboratory (1). The luteal slices were treated with PGE(2) or PGF(2)a at concentrations of 1 and 10 ng/ml each. Untreated luteal slices continued to release significant amounts of progesterone over the entire period of incubation (30 to 360 minutes). There was a progressive increase in progesterone accumulation following treatment with PGE(2) at both concentrations. The mean progesterone values were significantly higher in the PGE(2)-treated groups at all incubation periods than in the controls. Progesterone values at 10 ng/ml were higher (P<0.05) than at 1 ng/ml. Treatment with PGF(2)a decreased (P<0.05) progesterone release at 60 to 360 minutes of incubation compared with that of the corresponding controls for each incubation period. However, there appeared to be no differences (P>0.05) in mean progesterone values between the two concentrations of PGF(2)a. The results of this study showed that PGE(2) enhanced the release of progesterone by caprine luteal tissues, whereas PGF(2)a inhibited its release.     

Preliminary report on induction of estrus with multiple eCG injections in Colored Mohair goats during the anestrus season

This trial was conducted to evaluate the effectiveness of multiple eCG injections in the induction of estrus and pregnancy in Colored Mohair goats during the anestrus season. It was also aimed to determine total dose of eCG required for induction of estrus. Ten multiparous and lactating goats were used. The goats were randomly divided into two groups and treatments were started on May 22. Group eCG (n=5) was treated with eCG intramuscularly for 6 days. Daily dosages of eCG from May 22 to May 27 were 300 IU, 200 IU, 200 IU, 100 IU, 100 IU and 50 IU, respectively. Goats in control group received no treatment. Blood samples were taken from animals in each of the two groups just before and after the beginning of the treatments and serum progesterone concentrations were assayed by RIA. Starting on the fourth day after the first treatments, goats were exposed to fertile bucks twice daily for 30 min to detect standing heat. The estrus goats were allowed to be mated by the bucks. Pregnancies were determined 40 days after mating by real-time ultrasonography. One goat on day 5 and three goats on day 7 exhibited behavioral estrus in eCG group (80%) after the first eCG injection. Three of them (75%) became pregnant. None of the goats in the control group exhibited behavioral estrus. Mean serum progesterone concentrations had prominent elevations indicating ovulation in eCG group, but not in control group, after 20 days from the first treatments. Progesterone concentrations of eCG group were significantly different than those of control group on days 20 and 28 (P<0.05). The results suggest that divided multiple injections of a total 950 IU eCG are effective without progestagen pretreatment in the induction of estrus and obtaining successful pregnancy and live kids in Colored Mohair goats during the anestrus season.     

The effect of oxytocin and PGF2alpha on the uterine involution and pregnancy rates in postpartum Arabian mares

In this study, the effects of oxytocin and an analog of prostaglandin (cloprostenol) on the uterine involution and pregnancy rates were investigated. Mares received 3 ml of 0.9% NaCl in Group C (n=10), 30 IU/mare of oxytocin in Group O (n=10) and 250 microg/mare of cloprostenol in Group P (n=10) within 12h after parturition. The gravid uterine horn's cross-sectional diameter was measured by ultrasonography. The mean uterine diameters did not differ significantly between the treatment (O and P) and the control (C) groups (p>0.05). The difference between the postpartum ovulation periods (Group C: 12.6+/-0.72 days, Group O: 15+/-1.33 days, Group P: 14.6+/-1.11 days), the pregnancy rates at foal heat (Group C: 60%, Group O: 60%, Group P: 80%) and the embryonic death rates at foal heat (Group C: 33.3%, Group O: 16%, Group P: 25%) were not found to be statistically significant between the treatment and the control groups. The mean progesterone concentrations were similar in all groups and decreased continuously from parturition to until foal heat (Group C: from 2.43+/-0.24 to 0.66 ng/ml, Group O: from 3.07+/-0.6 to 0.27+/-0.27 ng/ml and Group P: from 2.8+/-0.44 to 0 ng/ml) (p>0.05). In conclusion, it was decided that the oxytocin and PGF2alpha treatments performed on the mares with the purpose of stimulating involution had no effect on the duration of parturition-first ovulation, the shrinkage of the uterus diameter, the pregnancy and embryonic death rates.     

The effects of buck teasing on synchronization of estrus in goats after intravulvo-submucosal administration of cloprostenol

A study was conducted on 35 East African shorthorned female goats to determine if a combination of buck teasing and low doses of a prostaglandin (PGF(2) alpha) analogue, cloprostenol, given intravulvo-submucosally (i.v.s.m.) would be suitable for synchronization of estrus. Goats were allotted, with the onset of estrus, to seven groups (n = 5 goats per group). Five of the seven groups received varying doses of cloprostenol: Group 1 (125 mug cloprostenol i.m. per goat); Group 2 (62.5 mug cloprostenol i.v.s.m. per goat); Group 3 (62.5 mug cloprostenol i.v.s.m. per goat plus buck teasing); Group 4 (31.25 mug cloprostenol i.v.s.m. per goat); Group 5 (31.25 mug cloprostenol i.v.s.m. per goat plus buck teasing); Group 6 (buck teasing); Group 7, (2 ml physiological saline i.v.s.m. per goat, control group). Plasma progesterone concentration was measured on day of treatment and for 6 d thereafter. All goats in groups 1, 2, 3 and 5 exhibited estrus within 68 h. Thus, the number of goats receiving low doses of PG-cloprostenol intravulvo-submucosally observed in estrus increased (P < 0.05) with exposure to bucks. Exhibition of behavioral signs of estrus was maximal between 2 and 20 h after onset of signs of estrus. The exposure of females to males prior to intrauterine penetration was an advantage because copious mucus eased penetration.     

Effects of pregnancy, oxytocin, ovine trophoblast protein-1 and their interactions on endometrial production of prostaglandin F2 alpha in vitro in perifusion chambers

Pregnancy and intrauterine infusion of ovine trophoblast protein one (oTP-1) decrease oxytocin-induced secretion of prostaglandin F2 alpha (PGF) from the uterus. In the present study, effects of oTP-1 and pregnancy on endometrial secretion of PGF were examined in an in vitro perifusion system. In Experiment 1, endometrium from day 14 pregnant and cyclic ewes was perifused sequentially on both the lumenal and myometrial sides with Krebs Ringers Bicorbonate solution (KRB), KRB plus oxytocin (1 IU/ml) and KRB alone. Endometrium from pregnant ewes secreted more PGF from both lumenal and myometrial sides than endometrium from cyclic ewes (P less than 0.05). Oxytocin stimulated secretion of PGF from both sides of endometrium regardless of status. Secretion of PGF was greater from the lumenal surface of endometrium compared to myometrium (P less than 0.05) for pregnant and cyclic ewes. For Experiment 2, endometrium was collected from day 15 cyclic ewes and perifused sequentially with KRB, KRB plus 300 ng/ml of either Bovine Serum Albumin (BSA) or oTP-1, KRB with or without BSA or oTP-1 plus oxytocin (1 IU/ml) and then KRB alone. Oxytocin stimulated greater release of PGF from oTP-1-treated than BSA-treated endometrium. Pretreatment of endometrium with oTP-1 had the same effect on oxytocin-induced PGF secretion as cotreatment with oTP-1 and oxytocin. In Experiment 3, uterine horns of cyclic ewes were catheterized on day 10 of the estrous cycle, and infused with either oTP-1 or day 16 pregnant sheep serum proteins on days 12, 13 and 14. Endometrium was collected on day 15 and perifused sequentially with KRB, KRB plus oxytocin (1 IU/ml) and then KRB alone. Treatment of ewes with oTP-1 attenuated endometrial secretion of PGF in response to oxytocin. Results of this study indicate that: (1) pregnancy stimulates basal secretion of PGF from endometrium and has no effect on oxytocin-induced secretion of PGF in vitro; (2) short-term oTP-1 treatment enhances oxytocin-induced PGF secretion from day 15 cyclic endometrium and (3) long-term oTP-1 treatment in vivo inhibits oxytocin-induced PGF secretion in ewes.     

Effects of progesterone administered to dairy heifers on sensitivity of corpora lutea to PGF(2)alpha and on plasma LH concentration

To determine whether progesterone facilitates PGF(2)alpha-induced luteolysis prior to day 5 of the estrous cycle, 48 Holstein-Friestian heifers were assigned at random to four treatments: 1) 4 ml corn oil/day + 5 ml Tris-HCl buffer (control); 2) 25 mg prostaglandin F(2)alpha (PGF(2)alpha); 3) 100 mg progesterone/day (progesterone); 4) 100 mg progesterone/day + 25 mg PGF(2)alpha (combined treatment). Progesterone was injected subcutaneously daily from estrus (day 0) through day 3. The PGF(2)alpha was injected intramuscularly on day 3. Estrous cycle lengths were decreased by progesterone: 20.2 +/- 0.56, 19.2 +/- 0.31 (control and PGF(2)alpha); 13.2 +/- 1.40, and 11.7 +/- 1.27 (progesterone and combined). The combination of progesterone and PGF(2)alpha did not shorten the cycle any more than did progesterone alone (interaction, P>0.05). PGF(2)alpha treatment reduced progesterone concentrations on day 6 (P<0.05) and both progesterone and PGF(2)alpha reduced plasma progesterone on day 8 (P<0.01 and P<0.05, respectively). LH was measured in blood samples collected at 10- min intervals for 4 hr on day 4 from three heifers selected at random from each of the four treatment groups. Mean LH concentration for control heifers ranged from 0.35 to 0.63 ng/ml (overall mean, 0.49 ng/ml) and for progesterone-treated heifers ranged from 0.12 to 0.30 ng/ml (overall mean, 0.23 ng/ml). LH concentrations were greater in control heifers (P<0.01). The mean LH pulse rate for control heifers was 2.7 pulses/heifers/4 hr, while that for the progesterone-treated heifers was 1.7 pulses/heifer/4 hr. The mean pulse amplitude for control and progesterone treatments was 0.47 ng/ml and 0.36 ng/ml, respectively. Neither pulse amplitude nor frequency were different between treatment groups.     

Use of progestagen-gonadotrophin treatments in estrus synchronization of sheep

The main objective of this study was to investigate the effectiveness of certain progestagen-gonadotrophin treatments on synchronization of estrus in sheep. In Experiment I, 30 Chios ewes were treated at the beginning of the breeding season with medroxyprogesterone acetate (MAP) intravaginal sponges for 12 days and a single i.m. treatment of either FSH (Group 1,10 IU, n = 8; Group 2, 5 IU, n = 8; Group 3, 2.5 IU, n = 8) or eCG (Group 4, 400 IU, n = 6) at the time of sponge removal. Ten days after sponge removal laparotomy was performed to record ovarian response. Clinical estrus was observed in more (though not at a significant level) FSH treated than eCG treated sheep (62.5% versus 33.3%). Administration of 400 IU eCG resulted in the highest mean number of CL perewe ovulating (2.8 +/- 0.2), with administration of 10 IU FSH producing the next best results (2.1 +/- 0.3). Statistically significant differences in the mean number of CL per ewe ovulating were found only between ewes in Group 3 (1.7 +/- 0.4) and Group 4 (2.8 +/- 0.2) (P < 0.05). In Experiment II, 53 Chios and 30 Berrichon ewes were treated during the mid-breeding season with MAP intravaginal sponges for 12 days and a single i.m. treatment of either 10 IU FSH (27 Chios and 16 Berrichon ewes) or 400 IU eCG (26 Chios and 14 Berrichon ewes), at the time of sponge removal. Ewes that were in estrus on Days 2-4 and 19-23 after sponge removal were mated to fertile rams. No significant differences were recorded between treatment or breed groups in the proportions of ewes observed in estrus after treatment. In the Berrichon breed, FSH administration resulted in higher lambing rates (93.8% versus 57.1%, P < 0.05) and higher mean number of lambs born per ewe exposed to rams (1.4 +/- 0.2 versus 0.8 +/- 0.2, P < 0.05) than that of eCG. After treatment with eCG, the mean number of lambs born per ewe exposed to rams was higher in the Chios than the Berrichon breed (1.4 +/- 0.2 versus 0.8 +/- 0.2, P < 0.05). After treatment with FSH, the lambing rate was higher in the Berrichon than the Chios breed (93.8% versus 63.0%, P < 0.05). In conclusion, a single FSH treatment (5 or 10 IU) at the end of progestagen treatment appears to be more effective than eCG for the induction of synchronized estrus in sheep at the beginning of the breeding season, with no cases of abnormal ovarian response observed. During the mid-breeding season FSH (10 IU) appears to be equally as effective as eCG (400 IU) in respect of lambing rate and mean number of lambs born per ewe.     

Effects of pregnancy, oxytocin, ovine trophoblast protein-1 and their interactions on endometrial production of prostaglandin F2α in vitro in perifusion chambers

Pregnancy and intrauterine infusion of ovine trophoblast protein one (oTP-1) decrease oxytocin-induced secretion of prostaglandin F2α (PGF) from the uterus. In the present study, effects of oTP-1 and pregnancy on endometrial secretion of PHF were examined in an in vitro perifusion system. In Experiment 1, endometrium from day 14 pregnant and cyclic ewes was perifused sequentially on both the lumenal and myometrial sides with Krebs Ringers Bicorbonate solution (KRB), KRB plus oxytocin (1 IU/ml) and KRB alone. Endormetrium pregnant ewes secreted more PGF fro both lumenal and myotrial sides than endometrium from cyclic ewes (P<0.05). Oxytocin stimulated secretion of PGF was greater from the lumenal surface of endometrium compared to myometrium was collected from day 15 cyclic ewes and perifused sequentially with KRB, KRB plus 300 ng/ml of either Bovine Serum Albumin (BSA) or oTP-1, KRB with or without BSA or oTP-1 plus oxytocin (1 IU/ml) and then KRB alon. Oxytocin stimulated greater release of PGF from oTP-1-treated than BSA-treated endometrium. Pretreament of endometrium with oTP-1 has the same effect on oxytocin-induced PGF section was cotreatment with oTP-1 and oxytocin. In Experiment 3, uterine horns of cyclic ewes were catheterized on day 10 of the estrous cycle, and infused with either oTP-1 or day 16 pregnant sheep serum proteins on days 12, 13 and 14. Endometrium was collected on day 15 and perifused sequentially with KRB, KRB plus oxytocin (1 IU/ml) and then KRB alone. Treatment of ewes with oTP-1 attenuated endometrial secretion of PGF in response to oxytocin. Results of this study indicate that: (1) preganancy stimulates basal secretion of PGF from endometrium and has no effect on oxytocin-induced secretion of PGF in vitro; (2) short-term oTP-1 treatment enhances oxytocin-induced PGF secretion from day 15 cyclic endometrium and (3) long-term oTP-1 treatment in vivo inhibits oxytocin-induced PGF secretion in ewes.     

Plasma concentrations of luteinizing hormone and progesterone during superovulation of dairy cows using follicle stimulating hormone or pregnant mare serum gonadotrophin

Eighteen lactating Holstein cows were randomly divided into three groups of equal size. Six cows were not superovulated; the remaining cows were superovulated using either FSH-P or PMSG beginning on Day 12 of the estrous cycle (day of ovulation = Day 0). Animals treated with FSH-P were injected intramuscularly (i.m.) with 4 mg FSH-P every 12 h for 5 d. PMSG was administered i.m. as a single injection of 2350 IU. Cloprostenol (PG, 500 ug) was injected i.m. 56 and 72 h after commencement of treatment and at the same time in the cycle of controls. All cows were inseminated 56, 68 and 80 h after the first PG injection. Blood samples (5 ml) were collected daily and every 15 min for a period of 9 h on Days -1, 0, 2, 8 and 10, with continuous blood sampling at 15-min intervals during Days 3 to 6. Ovulation rate was 27.7 +/- 8.22 in animals treated with PMSG, and 8.0 +/- 3.2 embryos per donor were recovered. In the FSH group, ovulation rate was 8.3 +/- 1.48 and 3.0 +/- 1.1 embryos per donor were recovered. Progesterone concentrations were similar in all three groups until the onset of the LH surge, when progesterone concentrations were greater (P<0.05) in animals of the PMSG group. After the preovulatory LH surge, concentrations of progesterone started increasing earlier (44 h) in cows treated with PMSG, followed by FSH-treated cows (76 h) and controls (99 h). The LH surge occurred earlier (P<0.05) in PMSG-treated cows (37 h after first PG treatment), than in animals treated with FSH-P (52 h) or controls (82 h). In animals treated with FSH-P, the magnitude of the preovulatory LH surge (24.2 +/- 1.02 ng/ml) was higher (P<0.05) than in the other two groups (PMSG = 17.1 +/- 2.04 ng/ml; control, 16.7 +/- 1.24 ng/ml). Superovulation with FSH-P or PMSG did not affect either mean basal LH concentration, frequency or amplitude of LH pulses during Days -1, 0, 2, 3, presurge periods, or Days 8 and 10 post-treatment. At ovariectomy, 8 d post-estrus, more follicles > 10 mm diam. were observed in the ovaries after treatment with PMSG (8.5 +/- 5.66) than after treatment with FSH-P (0.7 +/- 0.42) (P<0.05). Maximum concentrations of PMSG were measured 24 h after administration. Following this peak, PMSG levels declined with two slopes, with half-lives of 36 h and 370 h.     

Endocrine and superovulatory responses in heifers pretreated with FSH or bovine follicular fluid

This study examined the effects of altered serum FSH concentration on subsequent ovarian response to superovulation. Synchronized heifers were assigned randomly on Day 1 of the cycle (estrus = Day 0) to three pretreatment groups that consisted of 6-d of saline (7ml, s.c., b.i.d.; Group I), FSH-P (0.5 mg, i.m., b.i.d.; Group II) or charcoal-extracted bovine follicular fluid (BFF; 7 ml, s.c., b.i.d.; Group III) injections. Superovulation was initiated on Day 7 and consisted of FSH-P in decreasing dosages over 4 d (4,3,2,1 mg; i.m., b.i.d.), with cloprostenol (500 mug) on the morning of the third day. A second replicate with 14 heifers was conducted using the same protocol but twice the pretreatment dosage of FSH-P (1 mg) and BFF (14 ml). Endogenous plasma FSH decreased during BFF and FSH-P pretreatments compared to controls (P < 0.02). Endogenous FSH concentrations in both primed groups (II and III) were similar to control values (Group I) 12 h after the start of superovulation. Basal LH concentrations were not different between pretreatment groups. The interval from cloprostenol treatment to the preovulatory LH surge in Group III was 21.3 and 23.9 h longer (P < 0.0001) than it was in Groups I and II. The postovulation progesterone rise was delayed in Group III. The number of corpora lutea (CL) was lowest in the BFF-primed group (4.2 +/- 0.8) compared with the FSH-primed (7.4 +/- 1.3) and the control (12.0 +/- 1.8; P < 0.003) groups. In the FSH-primed group (0.68 +/- 0.06 cm(3)), CL volumes were larger than in the control group (0.45 +/- 0.03 cm(3)), whereas in the BFF-primed group (0.27 +/- 0.02 cm(3)) CL volumes were smaller compared with the control group (P < 0.0001). Mean FSH concentrations for 48 h preceding superovulation and the number of CL per cow were positively correlated (r = 0.55; P < 0.004; n = 26). We concluded that both FSH-P and BFF pretreatments decreased the superovulatory response of heifers to FSH-P. The mechanism for this would appear to be associated with reduced endogenous FSH prior to the start of superovulation.     

In vitro and in vivo viability of vitrified and non-vitrified embryos derived from eCG and FSH treatment in rabbit does

This study aimed to evaluate the in vitro and in vivo viability of vitrified and non-vitrified embryos derived from eCG and FSH treatments in rabbit does. Ninety-six nulliparous does were randomly subjected to consecutive superovulation treatments with eCG (20 IU/kg body weight intramuscularly (i.m.), eCG group), FSH (3 x 0.6 mg/doe at 24 h intervals i.m., FSH group), or without superovulation treatment (control group). Does were artificially inseminated 3 days later and ovulation was induced immediately by hCG (75 IU/doe intravenous). Seven experimental groups were differentiated: first FSH and eCG treatment, second FSH and eCG treatment, eCG-interchanged group (does with previous FSH treatment), FSH-interchanged group (does with previous eCG treatments) and control group. Embryos were collected in vivo by laparoscopy 76-80 h post-insemination in the first and second recovery cycles and post mortem in the third recovery cycles. The ovulation rate was significantly higher in does treated with the first-FSH than in those treated with eCG or in control does (25.2+/-2.0 versus 19.2+/-1.4 to 11.0+/-1.5, and 12.2+/-1.2, first-FSH, first-eCG to second-eCG and control groups, respectively, P < 0.05). Significant differences were observed in the total recovery influenced by ovulation rate in each group (20.3+/-2.2 to 9.4+/-1.2, first-FSH to control groups). Embryo donor rate (donor with at least one normal embryo) was similar among groups with an overall of 75.1%. The number of normal embryos recovered per doe with at least one normal embryo increased significantly in relation to ovulation rate (17.7+/-2.2 to 8.41+/-3, first-FSH and control groups). The vitrification of embryos negatively affected their in vitro development to hatched blastocyst in all groups (88.1% versus 48%, P > 0.05). However, after embryo transfer, this negative effect was only observed in superovulated vitrified embryos (16.8 and 12.8% versus 39.4% total born rate from eCG, FSH and control vitrified groups, P < 0.05). Results indicated that the primary treatments with eCG or FSH increased the number of normal embryos recovered per donor doe, but these embryos are more sensitive to vitrification protocols.     

Decreased pulsatile LH secretion in heifers superovulated with eCG or FSH

This study was designed to test the hypothesis that treatment with super-ovulatory drugs suppresses endogenous pulsatile LH secretion. Heifers (n=5/group) were superovulated with eCG (2500 IU) or FSH (equivalent to 400 mg NIH-FSH-P1), starting on Day 10 of the estrous cycle, and were injected with prostaglandin F(2alpha) on Day 12 to induce luteolysis. Control cows were injected only with prostaglandin. Frequent blood samples were taken during luteolysis (6 to 14 h after PG administration) for assay of plasma LH, estradiol, progesterone, testosterone and androstenedione. The LH pulse frequency in eCG-treated cows was significantly lower than that in control cows (2.4 +/- 0.4 & 6.4 +/- 0.4 pulses/8 h, respectively; P<0.05), and plasma progesterone (3.4 +/- 0.4 vs 1.8 +/- 0.1 ng/ml, for treated and control heifers, respectively; P<0.05) and estradiol concentrations (25.9 +/- 4.3 & 4.3 +/- 0.4 pg/ml, for treated and control heifers, respectively; P<0.05) were higher compared with those of the controls. No LH pulses were detected in FSH-treated cows, and mean LH concentrations were significantly lower than those in the controls (0.3 +/- 0.1 & 0.8 +/- 0.1, respectively; P<0.05). This suppression of LH was associated with an increase in estradiol (9.5 +/- 1.4 pg/ml; P<0.05 compared with controls) but not in progesterone concentrations (2.1 +/- 0.2 ng/ml; P>0.05 compared to controls). Both superovulatory protocols increased the ovulation rate (21.6 +/- 3.9 and 23.0 +/- 4.2, for eCG and FSH groups, respectively; P>0.05). These data demonstrate that super-ovulatory treatments decrease LH pulse frequency during the follicular phase of the treatment cycle. This could be explained by increased steroid secretion in the eCG-trated heifers but not in FSH-treated animals.