We evaluated the ovaries of 34 cows cross-bred of the Slovak Pied and Lowland Black-pied breeds which were culled and intended for slaughter during the winter type of feed rations. For superovulation treatment we used PMSG in the preparation Serum Gonadotropin (Bioveta, Nat. Ent., Ivanovice na Hané) and cloprostenol in the preparation Oestrophan inj. Spofa. We weighed the excised ovaries, fixed them in formalin 10% and made a quantitative evaluation of the surface follicles and differentiated them into recruited and selected or dominant follicles. We determined the concentration of 17 beta-estradiol and testosterone with the aid of the 3H RIA set from the firm Sorin after extraction by diethylether with separation of free and bound hormone with active charcoal. 72 hours after the giving of cloprostenol 43% reacted positively to superovulation treatment and after seven days a 50% positive response was recorded. After a dose of 2000 i. u. of PMSG (n = 6) embryo was obtained, whereas after 3000 i. u. of PMSG (n = 8) we flushed out eight embryos, of which four zygotes were suitable for transfer. After a higher dosage of PMSG there was an increase in the average weight of the ovaries, in right-hand ovaries significantly with P less than 0.05. After super-ovulation treatment the concentration of 17 beta-estradiol (E2) in the follicular fluid from follicles seven days after insemination was found to be so low as to be below the limit of detection, with the exception of four samples (mean = 8.60 nmol.l-1). The greatest concentration of E2 was from animals (n = 5) 72 hours after the giving of cloprostenol--1099.61 nmol.l-1) of follicular fluid. The concentration of testosterone was lower in the follicles of untreated cows in the follicular phase (mean = 5.92 nmol.l-1) compared with the follicles of super-ovulated animals the seventh day after insemination (mean = 14.12 nmol.l-1). The number of recruited and especially selected surface antral follicles 72 hours (n = 7) after the giving of cloprostenol and seven days (n = 8) after insemination was significantly higher in the group of brood cows reacting positively to superovulation in comparison with the animals which did not respond. It appears that the simultaneous monitoring of hormonal and morphological changes in the follicular system will help in objectivising the evaluation of the functional activity of stimulated follicles.

Electroejaculation (EE) is a widely used semen collection technique; but, it is stressful and painful for the animals. Considering these concerns, it may be important to develop practices to decrease the negative implications of EE on animals. Oxytocin and prostaglandin-F2alpha (PGF2α) stimulate the contractions of the muscles of the male genital tract. Therefore, the aim of this study was to analyze the effectiveness of the administration of oxytocin and/or a PGF2α analogue (cloprostenol) to bucks in relation to their stress response and sperm parameters before semen collection by EE was performed. Semen was collected with EE from 12 Gabon bucks in a 2 × 2 factorial arrangement (factors: with or without oxytocin, with or without cloprostenol). Each treatment was applied to different animals every 3 to 6 days, allowing all the animals to receive all the four treatments. The treatments applied to bucks before EE were as follows: 1) control (ConT), bucks received no hormonal treatment; 2) oxytocin (OxyT), bucks received 10 IU of oxytocin intramuscularly (IM) 30 s before beginning the EE; 3) PGF2α (PgT), bucks received 250 μg of cloprostenol IM 5 min before beginning the EE; and 4) oxytocin plus PGF2α (OxPgT), animals received treatment with both OxT and PgT. The number of electrical pulses, time length needed to achieve ejaculation, number of vocalizations, creatine kinase (CK) concentration and sperm parameters in goat bucks were recorded. The administration of cloprostenol and oxytocin before EE shortened the procedure and decreased the number of pulses and the pulse/voltage applied (P = 0.02 for all). This treatment also tended to decrease the number of vocalizations (P = 0.067). There were no treatment effects in the initial values; neither were there increases in heart rate and rectal temperature, or CK concentration. Seminal variables were not affected by the treatments. In conclusion, it would be important to consider the combined application of cloprostenol and oxytocin before EE, as it can shorten the process, reducing the electrical stimulus with positive effects on animal welfare and without affecting seminal quality in goat bucks.

The aim of the present study was to evaluate the effects of the PGF2α treatment given at the onset of a synchronization of ovulation protocol using a norgestomet (NORG) ear implant on ovarian follicular dynamics (Experiment 1) and pregnancy per AI (P/AI; Experiment 2) in cyclic (CL present) Bos indicus heifers. In Experiment 1, a total of 46 heifers were presynchronized using two consecutive doses of PGF2α 12 days apart. At first day of the synchronization protocol the heifers received implants containing 3mg of NORG and 2 mg of estradiol benzoate (EB). At the same time, heifers were randomly assigned to receive 150 mg of D-cloprostenol (n=23; PGF2α) or no additional treatment (n=23; Control). When the ear implants were removed 8 days later, all heifers received a PGF2α treatment and 1 mg of EB was given 24 h later. The follicular diameter and interval to ovulation were determined by transrectal ultrasonography. No effects of PGF2α treatment on the diameter of the largest follicle present were observed at implant removal (PGF2α=9.8±0.4 vs. Control=10.0±0.3 mm; P=0.73) or after 24 h (PGF2α=11.1±0.4 vs. Control=11.0±0.4 mm; P=0.83). No differences in the time of ovulation after ear implant removal (PGF2α=70.8±1.2 vs. Control=73.3±0.9 h; P=0.10) or in the ovulation rate (PGF2α=87.0 vs. Control=82.6%; P=0.64) between treatments were observed. In Experiment 2, 280 cyclic heifers were synchronized using the same experimental design described above (PGF2α; n=143 and Control; n=137), at random day of the estrous cycle. All heifers received 300 IU of equine chorionic gonadotropin (eCG) and 0.5 mg of estradiol cypionate (as ovulatory stimulus) when the NORG ear implants were removed. Timed artificial insemination (TAI) was performed 48 h after implant removal and the pregnancy diagnosis was conducted 30 days later. No effects on the P/AI due to PGF2α treatment were observed (PGF2α=51.7 vs. Control=57.7%; P=0.29). In conclusion, PGF2α treatment at the onset of NORG-based protocols for the synchronization of ovulation did not alter the ovarian follicular responses or the P/AI in cyclic Bos indicus beef heifers synchronized for TAI.

Nonlactating Leccese ewes (n = 61) were used during seasonal anestrus to investigate the effects on ovarian response and embryo production of adding defined amounts of p-LH to purified p-FSH as well as decreasing the FSH/LH ratio during treatment. The ewes were synchronized with FGA-impregnated intravaginal pessaries for 9 days and prostaglandin F2 alpha (Cloprostenol) injected on the seventh day. They were divided into six treatment groups in a 3 x 2 factorial design: three amounts of purified p-LH (100, 50 or 25% equivalent to 525, 262 or 131 IU p-LH) x 2 regimen of p-FSH and p-LH administration (constant or decreasing FSH/LH ratio). Each ewe received a total of 525 IU p-FSH at a decreasing dose, twice daily over a 3-day period. Group I (n = 11), Group II (n = 10) and Group III (n = 10) were treated with p-FSH supplemented with p-LH at 100%, 50% and 25%, respectively, of p-FSH dose and a constant FSH/LH ratio throughout the treatment period. Group IV (n = 10), Group V (n = 10) and Group VI (n = 10) were treated with p-FSH supplemented with p-LH at 100%, 50% and 25%, respectively, of p-FSH dose but with a decreasing FSH/LH ratio over the 3 days of the treatment: 1.7-0.86-0.43 for Group IV; 3.4-1.7-0.86 for Group V; 6-3-1.5 for Group VI. Embryos were flushed surgically on Day 6 after estrus. The ovulation rate did not differ among the groups (8-12.8). Superovulation with 100% p-LH and decreasing the FSH/LH ratio (Group IV) resulted in: (i) the highest ova recovery (9.8 +/- 1.7), and this was significantly different (P < 0.05) from the 25% p-LH treated group (Group VI; 5.0 +/- 1.7), (ii) the highest fertilization rate (90.6 +/- 9.2%), with a significant (P < 0.01) difference compared with the constant ratio regimen (Group I; 62.6 +/- 8.3%); (iii) the highest transferable embryo yield (6.4 +/- 1.1), differing significantly (P < 0.01) from Group VI (2.2 +/- 1.1) and Group I (2.7 +/- 1.0). It is concluded that decreasing the amount of p-LH added to purified p-FSH did not improve the superovulatory response of ewes during the anestrous period. Transferable embryo production was significantly improved when ewes were treated with p-LH equivalent to 100% p-FSH, with the FSH/LH ratio decreasing during treatment.

In this study we determined 1) if the immunoneutralization of PMSG affected the ovulatory response, the number of large follicles and embryo yield compared with that of PMSG alone or pFSH, and 2) whether the stage of the estrous cycle at which PMSG was injected affected the ovulatory response and yield of embryos in superovulated heifers. Estrus was synchronized in 99 (Experiment 1) and 71 (Experiment 2) heifers using prostaglandin F2alpha (PG) analogue, cloprostenol, given 11 d apart in replicate experiments over 2 yr. In Experiments 1 and 2, heifers were randomly allocated to 1 of 3 treatments (initiated at mid-cycle): Treatment 1--24 mg of pFSH (Folltropin) given twice daily for 4 d; Treatment 2--a single injection of 2000 IU PMSG; Treatment 3--2000 IU PMSG followed by 2000 IU of Neutra-PMSG at the time of first insemination. In Experiment 3, 116 heifers were given 2000 IU PMSG on Day 2 (n = 28), Day 3 (n = 27), Day 10 (n = 41) or Day 16 (n = 20) of the estrous cycle. The PG was given at 48 h (500 microg cloprostenol) and 60 h (250 microg cloprostenol) after the first gonadotropin treatment. Heifers were inseminated twice during estrus, and embryos were recovered on Day 7, following slaughter and graded for quality. The numbers of ovulations and large follicles >> or =10 mm) were also counted. There was no effect of treatment on ovulation rate in Experiment 1, but in Experiment 2 it was greater (P < 0.002) in heifers given PMSG (14.7 +/- 1.5) than pFSH (7.5 +/- 1.4) or PMSG-neutra-PMSG (8.7 +/- 1.5). The number of large follicles was higher following PMSG than pFSH treatment in Experiment 1, and it was higher (P < 0.004) in heifers given PMSG (5.5 +/- 0.8) than pFSH (1.12 +/- 0.7) or PMSG-neutra-PMSG (2.7 +/- 0.8) in Experiment 2. The use of Neutra-PMSG did not affect the numbers of embryos recovered or numbers of Grade 1 or 2 embryos, but it did decrease the number of Grade 3 embryos in both experiments. In Experiment 3, the ovulation rate decreased (P < 0.004) when PMSG was given on Day 3 (5.7 +/- 1.46) of the cycle rather than on Day 2 (12.3 +/- 1.64), Day 10 (13.4 +/- 1.45) or Day 16 (12.5 +/- 1.87). There was no effect of day of treatment on the numbers of large follicles. The mean numbers of embryos recovered were lower (P < 0.01) in heifers treated on Day 3 (2.1 +/- 0.67) than on Day 2 (6.8 +/- 1.0), Day 10 (6.4 +/- 0.86) or Day 16 (7.8 +/- 1.87). It is concluded that Neutra-PMSG given to heifers treated with PMSG did not improve embryo yield or quality and that treatment with PMSG early in the cycle can result in acceptable embryo yields provided sufficient time elapses between treatment and luteolysis.

Twenty-four Scottish Blackface ewes (mean weight 50.0 +/- 0.1 kg with ovulation rate 1.3 +/- 0.1) were randomly divided into 4 groups of 6 animals. Under general anesthesia, following the collection of a timed sample of ovarian venous blood, the ovaries of these animals were collected either on Day 10 of the luteal phase or 12, 24, and 48 h after a luteolytic dose of a prostaglandin (PG) F2 alpha analogue (cloprostenol 100 micrograms i.m.) administered on Day 10. All follicles greater than 3 mm were dissected from the ovaries and incubated in Medium 199 (M199) at 37 degrees C for 2 h, following which the granulosa cells were harvested and incubated in triplicate for 24 h in M199 with or without ovine FSH or ovine LH. Plasma and culture media samples were assayed for inhibin, estradiol (E2), androstenedione (A4), and testosterone (T) by specific RIA. After correcting for hematocrit, ovarian secretion rates were calculated from the product of the plasma concentration and flow rate. The rate of ovarian inhibin secretion during the luteal phase was similar from ovaries categorized on the basis of presence of luteal tissue (1.0 +/- 0.3 and 0.9 +/- 0.5 ng/min for CL present and absent, respectively), confirming that the ovine CL does not secrete appreciable amounts of inhibin. Inhibin secretion was higher (p less than 0.05) at 12 h after PG-induced luteolysis but not at 24 or 48 h compared to values for luteal phase control ewes. Although ovaries containing large estrogenic follicles (greater than or equal to 4 mm in diameter and classified as estrogenic from in vitro criteria) secreted the most inhibin (55%; p less than 0.05), both ovaries containing large nonestrogenic follicles (33%) and small (11%; less than 4 mm in diameter) follicles secreted appreciable amounts of inhibin. This contrasted strongly with E2 where greater than 80% of the steroid was secreted by large estrogenic follicles. The rate of ovarian inhibin secretion was positively correlated (p less than 0.05) with the rate of E2, A4, and T secretion. Overall, there was no significant effect of stage of cycle on follicular inhibin content after 2 h incubation in vitro, release of inhibin by follicles incubated in vitro, or synthesis of inhibin by granulosa cells cultured in vitro. FSH and LH had no effect on the production of either inhibin or estradiol by cultured granulosa cells. Follicular diameter was positively correlated (p less than 0.001) with follicular inhibin and steroid release. Follicular inhibin content after 2 h incubation in vitro was more highly correlated with inhibin release by incubated follicles (r = 0.7; p less than 0.001) than with inhibin synthesis by granulosa cells in vitro (0.4; p less than 0.01).(ABSTRACT TRUNCATED AT 400 WORDS)

Follicle stimulating hormone (FSH) is a glycoprotein hormone with a short half-life and has to be given twice daily for 3-4 days to induce superovulation in heifers. Since such a regimen is time consuming we compared the ovulatory response and yield of embryos in heifers following superovulation with either once or twice daily injections of pFSH for 4 days during the mid-luteal phase of a synchronized estrous cycle or during a prolonged luteal phase in heifers which had been immunized against prostaglandin F2alpha (PG). In Experiment 1, crossbred heifers (n = 42) previously actively immunized against a PG immunogen were superovulated in a 2 (cyclic or persistent corpus luteum) x 2 (once or twice daily injection) factorial plan. The heifers were superovulated with 75 units pFSH, which was injected subcutaneously once (22.5, 22.5, 15 and 15 units per day) or twice daily (9.3 units per injection) for 4 days. In Experiment 2, cyclic crossbred beef heifers (n = 80) were superovulated using pFSH which was given randomly to heifers once daily subcutaneously (T1) or twice daily intramuscularly (T2) using the same daily dose of 9, 7, 5, and 3 mg per day. Estrus was induced in all heifers in both experiments using 500 mug and 250 mug Cloprostenol 12 hours apart on the third day of pFSH injections. All heifers were inseminated twice with frozen-thawed semen at 12 and 24 hours after the onset of standing estrus or at 56 and 72 hours after the first PG if estrus was not observed. Embryos were recovered at slaughter and graded on a scale of 1 to 5 (1 = excellent, 5 = degenerated). Data were recorded for the number of corpora lutea (CL), large >>/=10 mm) and medium (5-9 mm) follicles, number of embryos recovered and embryo morphology. Data were analyzed by least squares analysis of variance procedures. In Experiment 1, there was no difference in ovulation rate between main effects. Fewer embryos were recovered from heifers with a persistent corpus luteum (pCL) and injected once daily (1.71+/-.75 vs 5.75+/-1.27) than from any other group. Heifers with pCL yielded lower (P < 0.05) numbers of freezable embryos than cyclic animals, regardless of injection regimen. In Experiment 2, T2 heifers had a significantly higher number of CL (16.4+/-1.7 vs 7.7+/-1.7; P = 0.0003), large follicles (4.1+/-0.5 vs 2.8+/-0.5; P = 0.04), medium follicles (6.4+/-0.7 vs 4.4+/-0.7; P = 0.04), embryos recovered (9.6+/-1.1 vs 4.9+/-1.1; P = 0.0025) and freezable embryos (4.7+/-0.7 vs 2.1+/-0.7; P = 0.014) than T1 heifers. It is concluded that a single daily subcutaneous injection of pFSH results in a lower superovulatory response than the twice daily regimen in heifers.

Experimental sows were divided into three groups treated as follows: Group I (n = 3): on Day 12 of the oestrous cycle i.m. injection of oxytocin (OT) at a dose of 0.25 I.U./kg b.w.; Group II (n = 4): on Day 12 and 13 of the oestrous cycle i.v. injections of OT (0.03 I.U./kg b.w.), and Group III (n = 3): on Day 13 of the oestrous cycle i.m. injection of cloprostenol (prostaglandin F2 alpha analogue; PG) at a dose of 500 micrograms. Blood samples were collected from the jugular vein for 2 h before and 2 h or 4 h after OT and PG treatment, respectively. Concentration of prolactin (PRL) was determined in all studied groups, whereas 13,14-dihydro-15-keto-PGF2 alpha (PGFM) was estimated in Group I and II. OT injections (i.v. or i.m.) Day 12 and 13 of the oestrous cycle raised its concentrations in the peripheral blood lasting for 50 and 120 min, respectively. But short lasting rise of PRL was caused by OT in 3 sows, whereas of PGFM in 2 sows only. In all other studied sows values of PRL and PGFM were during an experiment on the pre-treatment level. However, if PGF2 alpha analogue was injected on Day 13 of the cycle, it caused significant rise of PRL concentration (P less than 0.01) 20 min after treatment. PRL concentration measured after PG administration (7.0 +/- 0.7 ng/ml) was statistically higher (P less than 0.01) compared to the period proceeding PG injection (2.6 +/- 0.3 ng/ml).(ABSTRACT TRUNCATED AT 250 WORDS)

The objective of this study was to characterize the effect of dose and type of cloprostenol (CLO) on the luteolytic response of dairy cattle during the Ovsynch protocol under different oestrus cycle and physiological characteristics. Twelve non-lactating dairy cows and 111 lactating dairy cows were used in three experiments. In Experiment I, cows were synchronized so that they had only a 5.5- to 6-day-old corpus luteum (CL) at the time of the prostaglandin F2α (PGF2α ) treatment of Ovsynch. In Experiment II, cows were synchronized so that they had at least a CL of approximately 14 days old at the time of PGF2α treatment and an accessory CL if they had responded to the first GnRH of Ovsynch. Furthermore, in each experiment, cows received either a standard or a double dose of d-CLO as the luteolytic treatment. In Experiment III, lactating cows were blocked by parity and assigned to one of three luteolytic treatments during Ovsynch: 500 μg d,l-CLO, 150 or 300 μg of d-CLO. In Experiment I, the dose of d-CLO had an effect (p = 0.08) on the percentage of cows with full luteolysis, but not in Experiment II (p>> 0.1). More cows in Experiment II had full luteolysis than did cows of Experiment I (87% vs 58%, respectively; p = 0.007). In Experiment III, 87.1%, 84.4% and 86.2% lactating dairy cows had full luteolysis and 37.8%, 36.8% and 36.1% of cows became pregnant after treatment with 500 μg d,l-CLO, 150 or 300 μg of d-CLO, respectively (p>> 0.05).

Nonlactating Bos indicus x Bos taurus cows were used in three herds to determine the efficacy of different PGF2alpha treatments in combination with GnRH and melengestrol acetate (MGA) for a timed artificial insemination protocol. The start of the experiment was designated as d 0, at which time cows were assigned a body condition score and received 100 microg of GnRH. Cows were fed MGA (0.5 x mg x cow(-1) x d(-1)) on d 1 to 7. On d 7, cows received either a single injection of PGF2alpha (Lutalyse sterile solution; 25 mg; n = 297), a single injection of cloprostenol sodium (Estrumate; 500 microg; n = 297), or half the recommended dose of PGF2alpha (12.5 mg; n = 275) on d 7 and 8. On d 10, all cows were artificially inseminated and received 100 microg of GnRH. Pregnancy rates to the timed artificial insemination (39%) were not affected by treatment, herd, or treatment x herd. There was an effect (P < 0.01) of artificial insemination sire on timed artificial insemination pregnancy rate for one herd, but not the other two herds. Herd influenced (P < 0.05) 30-d pregnancy rates, but there were no treatment or treatment x herd effects as 72.3% of the cows became pregnant during the first 30 d of the breeding season. Results indicate that the type of PGF2alpha treatment administered 7 d after GnRH did not influence timed artificial insemination pregnancy rates in nonlactating Bos indicus x Bos taurus cows.

Oestrus synchronisation by means of PGF2 alpha analogues was followed by injection of Gonavet "Berlin-Chemie" which triggered off an LH peak, 2 to 3 hours from injection. Injection of Gonavet "Berlin-Chemie", 44 hours after PGF2 alpha application, caused synchronisation of all LH peaks. The interval between injection of Gonavet "Berlin-Chemie" and onset of ovulation amounted to 22 hours. The length of ovulation was not accurately determinable. Ovulation was successfully induced to all sheep by application of Gonavet "Berlin-Chemie", 44 or 48 hours after PGF2 alpha injection. Ovulation rates were 1.75 or 1.54. Luteolytic action on sheep of Cloprostenol "Jenapharm", a PGF2 alpha analogue, proved to be just as good as that of Oestrophan (SPOFA).

The effect of induction of parturitions in the 1-2 weeks of pregnancy was tested as exerted on the health of calves and on some biochemical and hematological indicators. The observations concerned 26 cows, out of which 14 cows (experimental group) were applied intramuscularly 500 micrograms of synthetic analog of prostaglandin F2 of alpha- cloprostenol. The other 12 cows were a control group. These indicators were determined in the blood of calves before colostrum intake, in 24 h, 5 and 15 days from the intake of the first colostrum ration: acid-base balance, hematocrit and leucocyte counts, in the blood plasma it was concentrations of glucose, urea, Na, K, Ca, inorganic P, vitamin A and E levels and AST and GMT activities. The same range of examinations was performed in the blood and/or in the blood plasma of cows, in addition to urea screening. Blood and urea samples were taken a month before and a month after parturition. No deviations from the normal state were found by the examination of highly-pregnant cows. Afterbirth retention was found in 87% cows of the experimental group after parturition, while it was only 9.8% in the control group. All the calves in the experiment had good vitality, very good health in the course of 15-day observation. There were not any significant differences in the birth weight and weight gains of the calves of experimental and control groups.(ABSTRACT TRUNCATED AT 250 WORDS)

The aim of this study was to determine the influence of follicular profiles over 4 days prior to superovulation on superovulatory responses. Eighty-eight Holstein cows were synchronized by two prostaglandin F(2)α injections given 11 days apart and conventionally superovulated between days 8 and 12 of the estrous cycle with 400 mg Folltropin-V given in decreasing doses over 4 days. Luteolysis was induced by 2 im injections of cloprostenol (2 ml) with the sixth and seventh injections of Folltropin-V. The ovaries of all cows were examined by ultrasonography with a real-time linear scanning ultrasound diagnostic system (Ls-300-A: Tokyo Keiki Co., Tokyo, Japan; 7.5 MHz Transducer) on days -3, -2, -1, 0 (initiation day of the superovulatory treatment=day 0). Data were analyzed by the GLM procedure of the SAS. Animals with a greater diameter of the largest follicle (F1; 13.4 vs 9.8 and 10.1 mm; p<0.007) and with a greater difference in the diameter of the first and second largest follicles (7.6 vs 4.5 and 3.8 mm; p<0.001) had the greater superovulatory response and produced the greater number of quality I embryos. In conclusion, the diameter of the F1 and the F1-F2 follicles were higher over a 4-day period prior to superovulation in animals yielding a high than a medium and a low number of quality I and I+II embryos.

The aim of this study was to determine the expression of fibroblast growth factor 22 (FGF22) in the bovine corpus luteum (CL) and to investigate the effects of in vivo total or partial cloprostenol-induced luteolysis on the mRNA abundance of FGF22 and its receptor, FGFR1B. Corpora lutea at different stages of development were then dissected from abattoir ovaries (n = 10/stage); a portion of the tissue samples was fixed in paraformaldehyde and the remaining samples were homogenized and subjected to total RNA extraction. To assess mRNA abundance of target genes during induced luteolysis, nineteen cows were synchronized and then randomly assigned to a Latin square design as follows: Control; 2 administrations of prostaglandin F2α (PGF2α, total luteolysis; 2 × 250 μg of cloprostenol sodium) and 1/6PGF2α (partial luteolysis; 83.33 μg of cloprostenol sodium). FGF22 and FGFR1B expression levels were measured by RT-qPCR, and FGF22 protein expression was detected by immunohistochemistry. In summary, FGF22 mRNA was detected at all stages of CL development, and FGF22 protein was also detected in luteal tissue. FGF22 mRNA expression was lower at stage IV than at stage III (P < 0.05), and the same pattern was observed in luteal immunoreactivity. Furthermore, cloprostenol-induced luteolysis, both total and partial, increased FGFR1B mRNA abundance in luteal tissue (P < 0.05), but did not affect FGF22 mRNA abundance. In conclusion, these data suggest a potential role for the FGF22-FGFR1B system during development and regression of bovine CL.

Pregnancy rates to a single appointment insemination were compared in seven groups of beef or dairy heifers following estrus synchronization with the prostaglandin F(2a) product, cloprostenol, versus the progestín product, Syncro-Mate-B. For cloprostenol synchronization, two injections of cloprostenol were given 11 d apart, with insemination occurring at 61+/-1 h after the second injection. The Syncro-Mate-B treatment consisted of a norgestomet/estradiol injection and a norgestomet implant on Day 0, followed by insemination at 49+/-1 h after implant removal on Day 9. Treatments were coordinated so all heifers in each group were housed together at the time of and for 48 h before a common insemination time so that the treatment received by individual heifers was not known. Overall pregnancy rates did not differ between treatment groups: 42% for 111 heifers treated with cloprostenol and 38% for 108 heifers treated with Syncro-Mate-B. Four blood samples per heifer taken during each replicate showed that two groups (n = 67) had many noncyclic heifers, while five groups (n = 152) had very few. Differences in pregnancy rates between these categories existed for both estrus synchronization methods, 18 versus 53% for cloprostenol and 21 versus 45% for Syncro-Mate-B. Thus the two methods were equally effective for cyclic heifers and equally ineffective for noncyclic heifers.

The synthetic prostaglandin analogue cloprostenol has been prepared radiolabelled with 14C. The isotopic abundance of 14C at position C-15 was greater than 90% of the theoretical maximum. We have utilizted the high abundance of the 14C isotope for metabolism studies by preparing mixtures of [12C]:[14C]cloprostenol such that fragments detected by mass spectrometry contained characteristic isotope clusters analogous to those often obtained using stable isotopes.

The aim of this experiment was to improve the reproductive performance of a short-interval prostaglandin (PG)-based protocol for timed artificial insemination in sheep, using a short-term nutritional treatment. During the breeding season (March-April), 132 multiparous and 61 nulliparous Corriedale ewes grazing natural pastures (600 kg DM/ha, 8.5% CP), were allocated to two groups: 1, Control group (n=100) two injections of D-Cloprostenol (75 μg per dose, 7d apart: Synchrovine(®) protocol); and 2, Supplemented group (n=93) ewes in which stage of the oestrous cycle was synchronised with Synchrovine(®) protocol plus focus feeding of a protein supplement (33.8% CP) between PG doses (Day -7 to -2). Cervical AI was performed at fixed time (Day 0), 46 ± 1.0 h after the second PG injection using 150 million sperm per ewe. Ovulation rate (Day 10), pregnancy rate, prolificacy and fecundity at Day 69 were evaluated by ultrasonography. Ovulation rate at Day 10 (1.20 ± 0.05 vs. 1.22 ± 0.05), pregnancy (46 ± 0.05 vs. 56 ± 0.05), prolificacy (1.09 ± 0.04 vs. 1.06 ± 0.05), and fecundity (0.49 ± 0.06 vs. 0.59 ± 0.06) at Day 69, were similar between groups (P>0.05; Control and Supplemented group respectively). It is concluded that focus feeding for 6d with protein supplementation during a short-interval PG-based protocol (Synchrovine(®)) did not improve the reproductive outcome associated with this protocol.

Trials were carried out on 1184 dairy cows calved at least six weeks before treatment and 255 heifers to determine effectiveness of the prostaglandin analogue, cloprostenol to control estrus. In trial 1, following two injections of cloprostenol given 12 days apart, there was no difference in calving rate following AI either at 72 and 96 hr after treatment (71 163 ) or at a detected estrus (53 118 ) compared to control cows bred at estrus (54 110 ). In trial 2, treated cows were injected once after 5 to 7 days of estrous detection and AI. The calving rate following AI either at 72 and 96 hr after cloprostenol (46 100 ) or at a detected estrus (39 71 ) was similar to that in control cows bred at estrus (45 86 ). In trial 3, cows were bred at a detected estrus after the first cloprostenol injection. Twelve days after this injection, cows not bred were given a second injection and bred 72 and 96 hr later. The calving rate in treated cows bred at estrus after the first injection (66 138 ) was similar to calving rate in controls (55 95 ). However, calving rate in cows given a second injection and bred 72 and 96 hr later was significantly (P angle 0.05) lower (30 98 ). Similar results were obtained in heifers, except calving rate in trial 3 after the second cloprostenol injection was not reduced.

The objectives of this experiment were to compare the effects of prostaglandin F(2alpha) (PGF(2alpha)) and its synthetic analogue treatment on postpartum bovine myometrial activity with and without estrogen priming. Sixteen multiparous, normal postpartum Holstein cows were randomly assigned to the following four treatment groups: saline PGF(2alpha), cloprostenol and fenprostalene. Myometrial activity was recorded using a catheter containing a miniature pressure transducer placed in the previously gravid horn via the cervix. Spontaneous myometrial activity was recorded at 48 h post partum for 60 min in all cows. Saline (5 ml,i.m.), PGF(2alpha) (25 mg,i.m.), cloprostenol (500 ug,i.m.) or fenprostalene (1 mg, s.c.) was administered to the cows according to the group. Myometrial activity was recorded until it returned to baseline. At the end of myometrial activity recording, 10 mg of estradiol cypionate (ECP) was injected i.m. to each cow. The same treatment schedule was repeated 12 h later. Results from this study indicate that PGF(2alpha) or its analogues, with or without ECP priming, do not increase myometrial activity in the postpartum cow. After ECP administration, both spontaneous and drug-induced myometrial activity increased; however, this increased myometrial activity was not statistically significant.

Circulating concentrations of 13,14-dihydro-15-keto PGF2 alpha (DHKF2 alpha), luteinizing hormone (LH) and prolactin (PRL) have been measured in cyclic ewes treated with continuous infusions of oxytocin, in order to investigate the mechanism by which the treatment delays luteal regression. Continuous infusion of oxytocin reduced prostaglandin F2 alpha (PGF2 alpha) secretion but had no detectable direct effect on LH or PRL. Oxytocin (3 nmol h-1 i.v.) given from Day 12 or 13 until Day 18 after oestrus delayed luteolysis, eight out of nine treated ewes not returning to behavioural oestrus until Day 29.1 +/- 3.2 (mean +/- s.e.m.; cycle length of control ewes 16.7 +/- 0.3 days). In the ewe in which oxytocin failed to prevent luteolysis, luteal regression had commenced before oxytocin treatment was started. In three ewes undergoing delayed luteolysis (cycle lengths, 21, 24 and 25 days) basal concentrations of PGF2 alpha (measured as DHKF2 alpha) were unchanged, but there was only one episode of PGF2 alpha secretion compared with 20 episodes in three control ewes. Prolactin secretion was pulsatile during oxytocin infusion, and levels were low following infusion in ewes with cycle length greater than 25 days while the corpora lutea were maintained. Circulating PRL concentrations were high in ewes undergoing delayed luteolysis but there was not discrete episode of PRL secretion associated with the pre-ovulatory LH surge in these animals. To investigate the possibility that the pattern of PGF2 alpha secretion was affected by depletion of oxytocin from corpora lutea, ewes previously treated with oxytocin to delay luteolysis were given a luteolytic dose of cloprostenol on Day 21 after oestrus. The amount of oxytocin secreted in response to cloprostenol was less than 10% of that seen in ewes similarly treated on Days 11-13 after oestrus. Low levels of luteal oxytocin may therefore reduce PGF2 alpha secretion in ewes undergoing delayed luteolysis.

Release of oxytocin by sliced or minced sheep luteal tissue in vitro was stimulated up to 1.6- and 2.3-fold by arachidonic acid and the calcium ionophore A23187 respectively. Prostaglandin (PG) F2 alpha and the PGF2 alpha analogue cloprostenol, and other potential agonists known to be active in vivo, including noradrenaline and acetylcholine, were ineffective, as was the phorbol ester tetradecanoylphorbol acetate (TPA). The ineffectiveness of PGF2 alpha was not due to a general unresponsiveness of the tissue in vitro, as PGF2 alpha reduced LH stimulation of tissue concentrations of cyclic AMP and activated inositol lipid hydrolysis. The effect of arachidonic acid was accompanied by release from the tissue of the cytosolic enzyme lactate dehydrogenase (at arachidonic acid concentrations below those required to release oxytocin) and its effect on oxytocin and lactate dehydrogenase release was mimicked by oleic and linolenic acids; arachidonic acid was concluded to act by a non-physiological physicochemical effect without conversion to an eicosanoid. As PGF2 alpha in vitro is known to raise intracellular Ca2+ concentrations in the large luteal cells that secrete oxytocin, and as A23187 stimulates oxytocin release in vitro in the presence and absence of TPA, it is concluded that in-vitro incubation results in an artifactual blockade of the oxytocin-releasing action of PGF2 alpha at an unidentified point distal to the effect on intracellular Ca2+.

The objective of the present study was to determine the ovarian response induced with the prostaglandin-based protocol Synchrovine (two doses of PGF2α given 7 d apart), as well as the fertility after FTAI. In Experiment 1, 15 females received the Synchrovine protocol using two different PGF2α analogues (Delprostenate vs. D-Cloprostenol). No differences in estrus response, time of ovulation and follicular dynamics were found between both groups (P < 0.05). The ovulation after Synchrovine was synchronized in a similar mean interval (68.8 ± 7.1 h) than when the females received a single dose of PGF2α (70.2 ± 20.7 h; P=NS), but the dispersion between the first and the last ovulation was reduced with this protocol (range 60-84 h vs. 24-96 h, respectively; P < 0.05). In experiment 2, 318 ewes were treated with the Synchrovine protocol and cervical FTAI was performed using different sperm cell concentrations. Pregnancy rate was higher using 200 × 106 and 100 × 106 sperm cells (38.2%, 39/102; and 34.9%, 38/109, respectively) than using 50 × 106 (23.4%, 25/107, P < 0.05). In Experiment 3, 444 ewes received the Synchrovine protocol and were assigned to receive 300 IU of eCG or not at the moment of the second dose of PGF2α, and cervical FTAI was performed 42 h or 48 h after the second dose of PGF2α. No effect was found related to the eCG administration nor the time of insemination. In Experiment 4, 342 received cervical or intrauterine insemination after treatment with the Synchrovine protocol, resulting in greater pregnancy rate for intrauterine insemination than cervical insemination (52.5%, 90/171 vs. 31%, 53/171, P < 0.05). These experiments demonstrate that the Synchrovine protocol effectively induces luteolysis, estrus and ovulation in most of the treated females, and ovulation is synchronized into a narrow window of 24 h. Pregnancy rate obtained with cervical FTAI is around 30-45%, with similar results using 100 × 106 or 200 × 106 sperm cells, the eCG administration seems not to be necessary, the type of PGF2α analogue does not appear relevant, and fertility is improved with intrauterine semen deposition.