Progesterone-releasing Device Research Articles

CASE REPORT: A SUCCESSFUL TREATMENT STRATEGY FOR CYSTIC OVARIAN DISEASE IN A DAIRY COW

A 5-year-old multiparous lactating Holstein cow was reported to have cystic ovarian disease with a history of whitish vaginal discharge on the 80th day postpartum. On the 83rd day postpartum, transrectal ultrasonography revealed a thick-walled cystic structure with visible cobwebs in the cavity, measuring 4.2[Formula: see text]cm × 3.4[Formula: see text]cm in diameter on the right ovary. The serum progesterone (P4) concentration was 6.82[Formula: see text]ng/mL, leading to a diagnosis of luteinized follicular cyst. Transvaginal aspiration of the cyst was performed to decrease the compression of ovarian stroma by the cyst, followed by intramuscular administrations of cloprostenol and buserelin. A 1.9[Formula: see text]cm diameter corpus luteum was detected on the right ovary nine days after aspiration, with a serum P4 concentration of 1.29[Formula: see text]ng/mL. Continual hormone treatment was followed, consisting of an injection of buserelin and an intravaginal progesterone-releasing device inserted for seven days. After seven days, two corpora lutea were noted on the right ovary with an average diameter of 2.8[Formula: see text]cm and 1.8[Formula: see text]cm, respectively. The device was removed and the cow showed a P4 concentration of 11.22[Formula: see text]ng/mL on that day. Estrus induction was conducted with two low doses of cloprostenol followed by an injection of gonadorelin, to induce a complete luteolysis and the following ovulation to fit a fixed-timed artificial insemination (AI). Pregnancy was confirmed 33 days after AI. Although the number of days open was 102 in this case, it took a total of 19 days from treatment to pregnancy.

Comparison of Gonadotropin-Releasing Hormone versus Estrogen-Based Fixed-Time Artificial Insemination Protocols in Grazing Bos taurus Suckled Beef Cows.

Fixed-timed artificial insemination (FTAI) protocols for beef cattle in South America are primarily based on estradiol esters and intravaginal progesterone-releasing devices (IVPD). The objective of this study was to determine the optimal gonadotropin-releasing hormone (GnRH)-based protocol as an alternative to the use of estrogen-based protocols in grazing Bos taurus suckling beef cows. All cows received an IVPD on the day of protocol initiation and prostaglandin F2α (PG) plus equine chorionic gonadotropin (eCG) treatments at the time of IVPD removal. In Experiment 1, cows (n = 235) were randomly assigned to one of four treatments: (i) 7-day estradiol = 2 mg of estradiol benzoate (EB) at IVPD insertion on Day 9 and 1 mg of estradiol cypionate (ECP) at IVPD removal on Day 2; (ii) 7-day GnRH = 10 µg of GnRH at IVPD insertion on Day 10, IVPD removal on Day 3 and GnRH at FTAI; (iii) 7 & 7 estradiol = PG at IVPD insertion on Day 16, EB on Day 9 and ECP at IVPD removal on Day 2; (iv) 7 & 7 GnRH = PG at IVPD insertion on Day 17, GnRH on Day 10, IVPD removal on Day 3 and GnRH at FTAI. In Experiment 2, cows (n = 462) were randomly assigned to one of four treatments: (i) 6-day estradiol = EB at IVPD insertion on Day 9, IVPD removal on Day 3 and GnRH at FTAI; (ii) 7-day estradiol; (iii) 7-day GnRH; (iv) 7 & 7 GnRH. In Experiment 1, plasma progesterone concentrations and percentage of cows with a corpus luteum (CL) at IVPD removal, and pregnancy per AI (P/AI) were greater for cows subjected to GnRH-based protocols compared with cows subjected to estrogen-based protocols (p < 0.01). In Experiment 2, cows subjected to the 7 & 7 GnRH protocol had the greatest P/AI (p < 0.01). In summary, GnRH-based FTAI protocols resulted in similar or greater P/AI compared to estrogen-based FTAI protocols in grazing postpartum Bos taurus suckled beef cows. The greatest P/AI was attained with the 7 & 7 GnRH protocol.

Evaluation of minimally invasive estrus synchronization protocols in brown brocket deer (Subulo gouazoubira)

This study aimed to evaluate minimally invasive protocols for estrus synchronization in the brown brocket deer (Subulo gouazoubira). Females were submitted to Latin square design, in different treatments. All females received 0.25 mg of estradiol benzoate on the first day of treatment, concomitant with one of the following sources of progesterone: (1) DIP: an intravaginal progesterone releasing device for eight days, (2) MGA1x: once a day (in the morning) oral dose of 1 mg melengestrol acetate for eight days, (3) MGA2x: twice a day (morning and afternoon) oral doses of 0.5 mg of MGA for eight days, (4) P4LA: a single i.m. administration of 75 mg of long-acting progesterone (P4LA). Eight days after the beginning of each treatment, females received an i.m. administration of 265 µg of prostaglandin (PGF2α; cloprostenol). Treatment efficacy was evaluated by manifestation of behavioral estrus after treatment and concentration of fecal progesterone metabolites (FPM). The time to onset of estrus in treatment P4LA was significantly longer (180 ± 38.9 h) compared to DIP (63 ± 6.6 h), MGA1x (53 ± 14.4 h) and MGA2x (41 ± 10.1 h) (P = 0.008). According to individual baseline FPM and FPM concentration during the days after estrus, the corpus luteum formation was suggested in all females which responded to the treatments (93.75 %). Low synchrony, longer interval between PGF2α administration and onset of estrus suggest that the P4LA dose (75 mg) is too high and not effective for S. gouazoubira. DIP, MGA 1x and MGA 2x, were effective in estrus synchronization.

Effect of Different Protocols of Fixed-Time Artificial Insemination on Mucus, Ovarian Size, and Pregnancy of Mixed-Breed Cows in the Humid Tropics of Peru.

The objective of the research was to evaluate three synchronization protocols for fixed-time artificial insemination (FTAI) in Bos indicus with Bos taurus crossbred cows. Forty-five cows of 5 ± 1.6 years were selected. The Jsynch treatment consisted of the application of an intravaginal device plus benzoate; on day 8, the device was removed and PGF2α, estradiol cypionate plus eCG was applied, and the FTAI was performed at 48-52 hours after. Conventional treatment consisted of the application of an intravaginal device plus benzoate; on day 8, the device was removed and PGF2α plus eCG was injected, and on day 9, estradiol benzoate was administered, and FTAI was performed at 30 hours. The Ovsynch treatment consisted of the application of GnRH, and on day 8, PGF2α was applied, on day 9, GnRH was applied again, and on day 10, FTAI plus GnRH was applied. The diagnosis of pregnancy was determined by transrectal ultrasound 45 days after the FTAI. The Jsynch (39.1%) and conventional (39.1%) treatment showed higher pregnancy compared to the Ovsynch treatment (21.7%) of pregnancy. The presence of crystalline mucus at the time of the FTAI was significantly associated with pregnancy. The results of this investigation indicate that it is possible to obtain acceptable pregnancy rates with the FTAI in B. indicus with B. taurus crossbred milk-producing cows, and treatments with progesterone-releasing devices plus eCG can improve the reproductive performance of cows.

Ovine endometrial estrogen receptor expression is altered following PG-600 administration.

Dysregulation of the estrogen receptor 1 (ESR1) expression during the establishment of pregnancy could contribute to reduce fertility reported in ewes treated with PG-600. The objective of this study was to evaluate the effect of treatment with PG-600 on ESR1 expression in the ovine endometrium during early diestrus. Polypay ewes (n = 24) that had exhibited an oestrous cycle of normal duration (16-18 days) were treated with intravaginal progesterone-releasing device (CIDR) for 9 days. Cloprostenol was administrated two days before CIDR withdrawal. On the day of CIDR withdrawal (day 0), ewes received a 5mL intramuscular injection of PG-600 (400 IU equine chorionic gonadotropin and 200 IU human chorionic gonadotropin) or saline. Blood samples were collected before treatment and on the day of tissue collection to determine serum estradiol-17β and progesterone concentrations using radioimmunoassay. On days 4 and 7, six ewes from each treatment group were anaesthetised and a laparotomy was performed to obtain intercaruncular endometrial samples. Endometrial samples were collected ipsilateral to the ovary bearing the highest number of corpora lutea. An estradiol exchange assay was used to determine ESR1 concentration. Estradiol concentrations did not differ by time or treatment, but progesterone concentrations were significantly higher in the PG-600-treated group on day 7 despite a similar number of corpora lutea. Endometrial ESR1 concentration was significantly reduced on day 7 in the PG-600 group. In conclusion, although progesterone was higher than controls on day 7, ESR1 did not differ from controls suggesting that treatment with PG600 is unlikely to impair reproductive potential.

126 Effect of oestrus synchronisation protocol with a high dose of oestradiol and an intravaginal progesterone-releasing device on the endometrial epidermal growth factor concentrations and fertility in recipient cows

Reproduction, Fertility and Development is an international journal publishing original research , review and comment in the fields of reproduction and developmental biology in humans, domestic animals and wildlife

Relationship between GnRH-induced LH increase profiles in the serum and vaginal mucus of Japanese Black beef cows.

This study aimed to investigate the relationship between increases in the luteinizing hormone (LH) profiles in the serum and vaginal mucus of cows induced by gonadotropin-releasing hormone (GnRH). Samples for LH determination were collected from Japanese Black beef cows during estrus, which was induced with a controlled internal progesterone-releasing device and the administration of cloprostenol immediately before GnRH administration and every 30 min from the start of GnRH administration until 6.5 h. The peak serum LH concentration was clearly identified at 2.5 h post-GnRH administration, with serum concentrations returning to near-pre-GnRH-administration values after 6.5 h, whereas the peak vaginal mucus LH concentration was identified 4.5 h after GnRH administration. These results indicate that the LH secretion peak in vaginal mucus appeared about 2 h after peak LH secretion in the serum.

EFECTO DE LA EXPRESIÓN DE CELOS Y LA ADICIÓN DE GnRH SOBRE LA TASA DE PREÑEZ EN VACAS HOLSTEIN EN LACTANCIA SINCRONIZADAS CON ESTRADIOL Y DISPOSITIVOS CON PROGESTERONA

The aim of this investigation was to evaluate the effect of the addition of GnRH at the beginning and end of a treatment with progesterone-releasing devices (P 4 ) and estradiol (E2) and the expression of estrus on pregnancy rates (PR) of lactating dairy cows inseminated at fixed time (FTAI). The estrus synchronization treatment consisted on the insertion of a P 4 device for 8 days and the administration of estradiol benzoate (EB) on the day of insertion and estradiol cypionate (ECP) at the time of device removal to induce ovulation. Experiment 1 was designed to determine whether the addition of GnRH at the start of the protocol improved the PR and if the division of the time of artificial insemination (AI) improved PR. The addition of GnRH on Day 0 did not improve PR (44% vs 40%) but the AI of cows showing estrus at 48 h and the administration of GnRH at 48 h and AI at 60 h of those not showing estrus resulted in higher PR than those cows that were FTAI at 48 h, regardless of estrus expression (53% vs 31%; P &lt;0.01). Experiment 2 was designed to study follicular dynamics and assess whether the PR varies using different times of AI (48 h vs 60 h), according to the expression of estrus. The division of AI and adding GnRH at 48 h decreased the dispersion in the interval between AI and ovulation. There was an interaction (P&lt;0.05) between the time of AI and expression of estrus. Pregnancy rates were higher in cows in estrus at 48 h that were AI at that time (47.8%) and those that were not in heat at 48 h and were AI at 60 h (53.4%) than those who were not in estrus at 48 h and were FTAI at that time (19.4%) and those that were in estrus at 48 h and were FTAI at 60 h (29.7%). In Experiment 3 PR was evaluated based on the addition or not of GnRH to cows not showing estrus at 48 h. Pregnancy rate was higher (P&lt;0.05) in cows that were not in estrus at 48 h, that received GnRH at that time and were AI at 60 h than in cows not showing estrus and 48 h that were also AI at 60 h but without GnRH (56.0% vs 39.8%). Experiment 4 evaluated factors that may affect PR in cows treated with the protocol developed in this experiment. It was found that the heat stress of January, a body condition score &lt;2.75 and the presence of only small follicles (&lt;10 mm and without CL) adversely affect PR. In conclusion, the results of this series of experiments confirm the hypothesis that the inclusion of a dose of GnRH and the modification of the time of AI increase PR in lactating dairy cows treated with P 4 devices and estradiol that does not express estrus at the time of FTAI.

Field observation on the use of PRID®Delta to induce estrus and ovulation in anestrous mares

To advance the time of the first estrus with ovulation, we administered intravaginally a progesterone-releasing devices PRID® Delta to 42 acyclic Arab-Barb mares for 11 days at different seasons: winter (n = 10), spring (n = 14), summer (n = 9) and autumn (n = 9). Twenty-seven of 39 mares that kept their coils responded to the PRID® Delta treatment with estrus and ovulation during the 42-day observation period, in winter (4/10, 40%) mares, in spring (9/13, 69%), in summer (7/7, 100%) and autumn (7/9, 78%) mares (P &lt;0,05). At Day 2 of PRID® Delta treatment, mean initial of progesterone concentrations was significantly increased in all mares in winter (7.20 ± 0.49 ng mL-1), spring (7.30 ± 0.64 ng mL-1), summer (7.5 ± 0.58 ng mL-1 ) and autumn ( 7.60 ± 0.71 ng mL-1) (P &lt;0,05). Total concentration of progesterone (area under curve (AUC)) during the treatment period revealed highest values in spring (67.95 ± 2.40 ng mL-1h-1) followed by autumn (65.20 ± 1.37 ng mL-1 h-1), winter (54.19 ± 7.00 ng mL-1 h-1) and summer 52.23 ± 3.32 ng mL-1 h-1; P &lt; 0.05). In conclusion, administration of the intravaginal device releasing progesterone PRID® Delta was able to induce estrus and ovulation in mares at different times of the year. However, the efficacy of the treatment was not satisfactory in terms of efficacy compared to the season (low response rate in winter) and synchrony of intervals from removal of PRID® Delta to ovulation.

Comparison of the initial ovarian response, the synchrony of oestrus and ovulation and chronic stress response after administration of 100 or 250 μg of GnRH to randomly cycling Bos indicus cattle.

This study investigated the effects of administering saline, 100 or 250 μg of gonadotrophin releasing hormone (GnRH) on ovarian response, synchrony of oestrus and ovulation and chronic stress response in Bos indicus cattle. Randomised control. Animals were either left untreated (n=20) or on day 0 treated with an intravaginal progesterone releasing device and either saline (n=24), 100 μg (n=35), or 250 (n=35) μg of GnRH, intramuscular (IM). Blood was sampled 1.4 h after administration of treatment to monitor concentrations of luteinising hormone (LH) and P4 in serum and again 5 days later. On day 5 intravaginal P4 releasing device were removed, cloprostenol was administered IM and again 8 h later. Oestrus and ovulation were then monitored with ultrasonography for 6.5 days. Hair was clipped on day 55 for analysis of hair cortisol concentrations (HCC). No significant differences were found between Saline and GnRH treatments in the odds of inducing a new corpus luteum (CL) and the synchrony of oestrus or ovulation. HCC did not differ significantly between treatments. Mean concentrations of LH in serum on day 0 were less in the Saline compared to 100 and 250 μg GnRH treatments but did not differ between different doses of GnRH. Mean concentrations of LH and the odds of inducing a new CL were not increased after administering 250 μg compared to 100 μg of GnRH. Animal handling events in the study did not influence HCC. Further research is needed to better optimise responses to GnRH in B. indicus cattle.

Relationship between the concentration of anti-Müllerian hormone and antral follicle count in pasture-managed Holstein cows in the high tropics.

We evaluated the relationship between plasma levels of anti-Müllerian hormone (AMH) and the number of antral follicles at the restart of the follicular wave in crossbred Holstein cows reared under extensive grazing systems over 2500 m above sea level. The study included 140 cows from 15 farms that were in average at the 75.3 ± 2.10 d post partum. Animals were synchronized according to the following regime: day 0 = intravaginal progesterone releasing device (IPD) + estradiol benzoate (EB); day 7: withdrawal of IPD + prostaglandin; and day 8: EB, for restart of the follicular wave on day 11. On this day 11, antral follicle counts (AFCs) were made by transrectal ultrasound, and a plasma sample was taken for the determination of AMH. The mean AMH plasma level was 0.06 ± 0.03 ng/ml and the mean AFC was 17.26 ± 0.38 follicles. A strong positive linear correlation was found between these two variables (r = 0.783, r = 0.613, P < 0.0001). Cows were categorized according to AMH concentration as high (>0.09 ng/ml), intermediate (0.09-0.05 ng/ml) or low (<0.05 ng/ml). Cows with high AMH presented a higher AFC (25.0 ± 2.21 follicles) than those with low AMH (14.08 ± 2.68 follicles; P < 0.001. Our results suggest that the cut-off value of AMH = 0.09 ng/ml may be useful for selecting donors in multiple ovulation embryo transfer programs involving cows with these characteristics. Our data further suggest that AMH plasma concentration correlates with AFC and can be used as an endocrine biomarker of the number of antral follicles present at a given moment of the estrous cycle in crossbred Holstein cows raised at altitudes above 2500 m.

Use of Intravaginal Progesterone-Releasing Device Results in Similar Pregnancy Rates and Losses to Long-Acting Progesterone to Synchronize Acyclic Embryo Recipient Mares.

The objectives of this study were: (1) to assess uterine features and serum progesterone concentrations of acyclic mares synchronized and resynchronized with intravaginal progesterone release device (IPRD), and (2) to compare pregnancy rates and losses of cyclic and acyclic embryo recipient mares treated with different synchronization protocols. In Experiment 1, mares (n = 12) received estradiol for 3 days (E2-3d), and then 24 h after the last injection, an IPRD was inserted and kept in place for 9 days. Three days after IPRD removal, mares were treated with E2-3d, and then a new IPRD was inserted and maintained for three days. Serum progesterone concentrations were assessed 2, 6, and 12 h after insertion and removal of IPRD, and then daily from the insertion of the first IPRD to one day after removal of the second IPRD. Experiment 2 was conducted with embryo recipient mares randomly assigned to four groups: (1) Cyclic: mares (n = 75) had ovulation confirmed after receiving a single dose of histrelin when a periovulatory follicle was first detected, (2) LAP4: acyclic mares (n = 92) were treated with E2-3d and then administered a single dose of LAP4 24 h after the last estradiol injection, (3) IPRD: acyclic mares (n = 130) were treated with E2-3d and an IPRD for 4–8 days, and (4) RE-IPRD: acyclic mares (n = 32) were synchronized as in the IPRD group but not used for embryo transfer (ET), then 8 to 15 days later, the mares were resynchronized with E2-3d and an IPRD for 4–8 days. In vivo-produced Day-8 embryos were collected and transferred 4–8 days after ovulation or progesterone treatments. Mares in IPRD and RE-IPRD groups had the intravaginal device removed immediately before ET, and then a new IPRD was inserted right after ET. Pregnancy diagnosis was performed at 5, 30, and 60 days after ET. Once pregnancy was confirmed, mares in the three acyclic groups received weekly injections of LAP4 (1.5 g) until 120 days of pregnancy. Mares in IPRD and RE-IPRD groups had the device removed three days after the first pregnancy diagnosis. In Experiment 1, progesterone concentrations increased rapidly starting 2 h after insertion of IPRD (p < 0.05); then, concentrations plateaued well above pregnancy maintenance until removal on days 9 and 3, respectively. Progesterone concentrations were reduced to baseline 24 h after IPRD removal (p < 0.05). For experiment 2, there was no difference in pregnancy rates across groups (65–74%) or pregnancy losses by 60 days of gestation (7–12%) (p > 0.05). In conclusion, the IPRD used herein resulted in a rapid increase and a sharp decline in progesterone concentrations upon its insertion and removal, respectively. Finally, our results demonstrated that IPRD could be a compatible alternative to LAP4 to synchronize and resynchronize acyclic embryo recipient mares.

Increasing conception rate by addition of a second prostaglandin injection in an Ovsynch and progesterone treatment programme for dairy cows not detected in oestrus before the start of the seasonal mating period

ABSTRACT Aims To assess the effect on conception rate to first service, 3- and 6-week in-calf rates, final pregnancy rate and the hazard of pregnancy, of addition of a second prostaglandin (PG) injection 24 hours after the first, in a synchrony programme combining Ovsynch and progesterone in pasture-based dairy cows that had not been detected in oestrus before the start of the seasonal mating period. Methods This prospective, negative-controlled study was conducted using anoestrous cows (n = 1,411) from nine spring-calving dairy herds in the Waikato region of New Zealand. Ovaries of cows not detected in oestrus were examined by transrectal ultrasonography and the presence of a corpus luteum determined. All cows were then treated with an intravaginal progesterone-releasing device and injected I/M with gonadorelin (Day −9). Cows were injected I/M with cloprostenol at device removal (Day −2) and on Day −1 were injected with either water (single PG; n = 720), or cloprostenol (double PG; n = 692). On Day 0 cows were injected again with gonadorelin, unless previously detected in oestrus, and were inseminated on Day 1. Based on dated pregnancy diagnosis by transrectal ultrasonography, cows were categorised as conceiving to first insemination, becoming pregnant in the first 3 or 6 weeks, or becoming pregnant by the end of the mating period. Results Cows in the double PG group had increased conception rate to first service (45.3 (95% CI = 45.1–45.4)% vs. 41.1 (95% CI = 41.0–41.3)%; p < 0.001), 3-week in-calf rate (53.4 (95% CI = 53.6–54.0)% vs. 49.2 (95% CI = 49.0–49.4)%; p < 0.001), and 6-week in-calf rate (67.2 (95% CI = 65.7-68.8)% vs. 63.5 (95% CI = 62.0-65.0)%; p = 0.014) compared to cows in the single PG group. Final pregnancy rate and hazard of pregnancy did not differ between treatment groups (p >0.2). Conclusions Addition of a second PG injection 24 hours after the first, increased conception rate to first service and the proportion of cows pregnant by 3 and 6 weeks after commencement of the mating period. Clinical relevance Improved outcomes can be achieved when treating those cows not detected in oestrus by the start of the seasonal mating period by addition of a second PG injection to the currently recommended treatment protocol for these animals.

Comparison of two intravaginal progesterone-releasing devices in shortened-timed artificial insemination protocols in beef cattle

Commercially available intravaginal progesterone (P4) devices differ in shape, surface area and P4 load, which may affect the resulting pregnancy per AI (P/AI) following timed-AI (TAI). The objective of this study was to compare two intravaginal P4 devices on estrus rate, follicular dynamics and P/AI in beef cattle subjected to shortened-TAI protocols. In Expt. 1, nulliparous heifers were randomly assigned to a P4-releasing intravaginal device (PRID-Delta, 1.55 g P4) or a controlled internal drug release (CIDR, 1.38 g P4) at the initiation of a J-synch protocol. Heifers that displayed estrus 72 h following device removal were TAI, or if not in estrus given GnRH at 72 h and TAI at 90 h. In Expt. 2, nulliparous heifers and non-suckling cows were randomly assigned to either PRID or CIDR groups and either 1 or 2 mg of estradiol benzoate (EB) at initiation of a J-synch protocol. All cattle were TAI concurrent with GnRH 72 h after device removal. In Expt. 3, nulliparous heifers and suckling cows were randomly assigned to either PRID or CIDR groups and initiated a 5-d Cosynch protocol, with TAI concurrent with GnRH 72 h following device removal. In each experiment, cattle received estrus detection patches at device removal, which were then scored from 0 to 3 based on color change between initial application and TAI; 0 = unchanged, 1 = ≤50% change, 2 = >50% change, 3 = missing. Estrus was defined to have occurred when the patch was scored 2 or 3. Transrectal ultrasonography was used to determine cyclicity, diagnose pregnancy in all experiments, and the size of the ovulatory follicle in Expt. 3. In Expt. 1, the estrus rate was greater (72.0% vs. 61.0%; P = 0.04) in the PRID compared to the CIDR group. In Expt. 2, a parity by EB dose interaction (P = 0.02) was attributed to an increased estrus rate (52.8% vs. 41.4%; P = 0.05) in heifers given 1 vs. 2 mg EB. In Expt. 3, there was no difference in the ovulatory follicle diameter at device removal (P = 0.22) or TAI (P = 0.28) between P4 groups. Treatment with a PRID tended (P = 0.10) to increase the P/AI in cows compared to a CIDR (73.5% vs. 61.0%). In all experiments combined, the overall P/AI tended to increase (55.2% vs. 51.0%; P = 0.08) and P/AI in cattle exhibiting estrus increased (64.4% vs. 59.7%; P = 0.02) in cattle given a PRID compared to those given a CIDR, respectively. In summary, the type of intravaginal P4 device affected estrus response and P/AI following TAI in beef cows.

Prostaglandin F2? as ovulatory stimulus in dairy cows and buffaloes raised in the Amazon biome

This study evaluated the effect of a prostaglandin F2? (PGF) analogue as an ovulatory stimulus in dairy cows and buffaloes raised in the Amazon biome. To this end, three experiments were performed in the state of Rondônia, located in the Amazon biome. In Experiment 1, 22 lactating dairy buffaloes received 2 mg of intramuscular (I.M.) estradiol benzoate (EB) on day 0 and an intravaginal progesterone-releasing device (CIDR) from day 0 to day 9 of the protocol. On days 8 and 9, all cows were given 500 ?g of I.M. d-cloprostenol (PGF analogue). On day 10, buffaloes were divided into two groups to receive 500 ?g of PGF (PGF group, n = 8) or no treatment (CTL group, n = 14), respectively. In Experiment 2, 16 lactating crossbred dairy cows (Holstein x Gir) received 2 mg of EB on day 0 and a CIDR insert from day 0 to day 8. On days 7 and 8, all cows were given 500 ?g of d-cloprostenol. On day 9, cows were divided into two groups to receive 500 ?g of d-cloprostenol (PGF group, n = 8) or no treatment (CTL group, n = 8), respectively. In Experiment 3, 16 lactating crossbred dairy cows (Holstein x Gir) were handled and treated similarly as in Experiment 2, although cows did not receive d-cloprostenol on day 8. Single-point outcome variables were analyzed using one-way analysis of variance (ANOVA), while proportions with dichotomous outcomes were analyzed with the chi-square test. In Experiment 1, there was no difference (P = 0.30) in the ovulation rate between groups, and, on average, 68% of the buffaloes ovulated. Moreover, the treatment did not affect the interval to ovulation (P = 0.61) nor the diameter of the preovulatory follicle (P = 0.47). As for Experiment 2, only one cow, from the PG group, did not ovulate. There were no differences between the CTL and PG groups (P = 0.69) in the moment of ovulation, which occurred in average 82 h after CIDR removal. Finally, in Experiment 3, cows treated with PGF ovulated earlier than those in the CTL group (62.5 ± 5.8 and 94.5 ± 13.5 h, respectively; P = 0.05). Collectively, these results suggest that PGF hastens ovulation in lactating dairy cows, whereas no effect was observed in dairy buffaloes.

Effect of the Estrus Expression on Follicular and Luteal Morphofunctional Characteristics and Fertility in Bos indicus females Synchronized for FTAI

Background: Recent studies have been conducted with the aim of improving the fertility rates in the FTAI programs in beef females. The observation of the estrus expression constitutes an important indicator of fertility in zebu females. Therefore, this work has as an objective to evaluate the impact of the estrus expression on the follicular, luteal and fertility morphofunctional characteristics of Nelore females synchronized for FTAI.Materials, Methods &amp; Results: Sixty five lactating female Nelore (Bos taurus indicus) were used. On a random day, denominated day 0 (D0), the 65 Nelore females received a progesterone-releasing device associated to the application of 2.0 mg of estradiol benzoate intramuscularly (IM). On D9, the progesterone-releasing intravaginal devices were removed and was administered 500 μg of cloprostenol sodium IM; 0.6 mg of estradiol cypionate IM and 300 UI of Equine Chorionic Gonadotropin IM. At this point, the animals were marked with a marking stick for the determination of the estrus expression. On D11 of the synchronization protocol, the animals were characterized in two groups: without estrus expression (WO/ ESTRUS) and with estrus expression (W/ ESTRUS). The evaluation of the follicle diameter (FOLD), of the follicle wall area (FOLA), of the follicle wall vascularization (FOLV) and the percentage of vascularization in the area of the preovulatory follicle wall (%FOLV) were conducted on D11 using B-mode ultrasonography and color Doppler and then the artificial inseminations were performed. The evaluation of the corpus luteum diameter (CLD), the total area of the corpus luteum (CLA), of the area of vascularization of the corpus luteum (CLV), of the percentage of vascularization of the in the area of the corpus luteum (% CLV) and the collection of blood for the evaluation of the serum levels of progesterone were carried out on D24. The analysis of the serum progesterone concentration were performed by the chemiluminescence method using the Access immunoassay systems Progesterone, with a sensitivity of 0.1 ng/mL. The diagnosis of gestation was carried out by transrectal ultrasonography on D45. The animals of the WITH ESTRUS group presented superior FOLD, FOLA, FOV (P &lt; 0.05) averages to those presented by the cows of the WITHOUT ESTRUS group. In relation to the luteal characteristics, in the WITH ESTRUS group the cows exhibited averages for CLD, CLA, CLV and P4 significantly higher than those of the WITHOUT ESTRUS group. However, the bovines of the WITH ESTRUS group presented a % CLV similar to the presented by the females of the WITHOUT ESTRUS group. As for the fertility rates, there was difference between the experimental groups WITH ESTRUS and WITHOUT ESTRUS.Discussion: The present work demonstrated the impact of the estrus expression on the follicular morphological parameters, therefore in accordance with other studies. These authors show a relation between the estrus expression and levels of estradiol, which is directly related to the sperm transport in the female reproductive tract, oocyte maturation and fertilization directly affecting the fertility of females submitted to the FTAI program. Similarly, there was an interrelation between the estrus expression and the luteal morphological parameters, corroborating with the findings of some researches, where were verified higher luteal morphological parameters associated to higher conception rates in cows that demonstrated estrus behavior in the FTAI. Therefore, the estrus detection can be used as a tool to direct matings in synchronization protocols, promoting the identification of the animals with a higher probability of conception, owing to better follicular and luteal hemodynamic conditions.

Pregnancy rate to FTAI in Braford heifers submitted to J-Synch protocol

The objective of the present work was to evaluate the effect of J-Synch protocol on pregnancy rate (PR) of heifers artificially inseminated after detected estrus (DEAI) or at fixed-time (FTAI). Two hundred ninety-three Braford heifers were used. On day 0, all animals received 2.0 mg of estradiol benzoate administered intramuscularly (IM) and an intravaginal progesterone-releasing device (DIB, 0.5 g). Heifers were assigned to the following group: 1) J-Synch: on day 6, DIB devices were removed and 500 µg of d-Cloprostenol sodium (d-CS) was administered IM and paint was applied on tail base (tail-paint). On day 9 (60 h after DIB removal), heifers with ? 40% of the tail-paint rubbed off were inseminated. Those not showing estrus by 72 h after DIB removal received 100 µg of GnRH at that time and were FTAI. 2) Conventional: on day 7, DIB devices were removed, and 500 µg of d-CS and 0.5 mg of estradiol cypionate were administered IM and tail-paint. Forty-eight hours after DIB removal, heifers with the tail-paint rubbed off were DEAI. Those not showing estrus by 54 h after DIB removal were FTAI. Pregnancy rate was diagnosed by ultrasonography 30 days after FTAI in all heifers and did not differ between protocols (44.28% and 42.48%, P = 0.673). In both protocols, higher PR was observed in DEAI heifers (P = 0.047). In conclusion, the use of the J-Synch protocol generated similar PR to the Conventional protocol, allowing its use with the same efficiency. Furthermore, the DEAI generated better PR than the FTAI, regardless of the protocol used.

Reusing intravaginal progesterone releasing devices for oestrous synchoronization in ewes

In this study, the second use of an intravaginal progesterone-releasing device or controlled intravaginal drug release device (CIDR) was evaluated. After a first use of 11 days, the CIDR was again used for either nine or 12 days with 200 or 300 IU equine chorionic gonadotrophin (eCG) being injected on its removal. Sixty-four ewes were randomly distributed to four treatments (n=16/group): CIDR9+eCG200, CIDR9+eCG300, CIDR12+eCG200, and CIDR12+eCG300. The eCG was administered intramuscularly on withdrawal of the device. Thus, the experiment was a completely randomized design with a 2×2 factorial arrangement of treatments. Oestrus presentation did not differ between treatments (P =0.29). However, with the dose of 200 IU of eCG, oestrus presentation tended to increase (P =0.08). The onset and duration of oestrus, percentage of gestation, and return to oestrus did not differ between treatments (P &gt;0.05). Progesterone concentration in serum was greater (P &lt; 0.05) in ewes treated with CIDR12+eCG300. Prolificacy was greatest (1.44) with the CIDR12+eCG300 treatment and was different (P = 0.001) from the treatments CIDR9+eCG200 (1.21) and CIDR9+eCG300 (1.20), but not from the CIDR12+eCG200 treated ewes (1.31). The CIDR12+eCG300 treatement produced the highest percentage of twin births (45.8%) (P =0.001). Leaving the device in place for 12 days increased (P =0.001) the incidence of twin births. Use of the CIDR for a second time synchronized oestrus in ewes successfully with better fertility being obtained when the device was left in place for 12 days, and 300 IU of eCG was injected on its removal.&#x0D; Key words: gonadotropin, progesterone device, synchronization

Administering an additional prostaglandin F2α injection to Bos indicus beef cows during a treatment regimen for fixed-time artificial insemination

Two experiments were conducted to evaluate if an additional prostaglandin F2α (PG) injection during an estradiol-based estrous synchronization treatment regimen affects pregnancy rates resulting from fixed-time artificial insemination (FTAI) in Nelore cows. In Experiment 1, 1039 cows were administered estradiol benzoate and an intravaginal progesterone releasing device (CIDR) on d -11, an injection of PG on d -4, with CIDR removal and administration of estradiol cypionate and eCG occurring on d -2, and FTAI on d 0. Cows were administered an additional injection of PG (PG2) or saline (PG1) on d -2. Percentage pregnancy per FTAI on d 30 was greater (P = 0.01) in cows of the PG2 than PG1 group (54.5 % and 46.6 %, respectively). In Experiment 2, there was use of the same treatment regimen for estrous synchronization of 934 cows as that for Experiment 1 followed by FTAI, with there being diagnosis of whether cows had or did not have a corpus luteum on d -4. Response to estrous synchronization, largest follicle diameter at FTAI, and pregnancy per FTAI were greater (P ≤ 0.05) in cows of the PG2 than PG1 group with a body condition score (BCS) < 5.0 at FTAI (81.2 % and 72.6 %, 11.9 and 11.2 mm, 55.5 and 45.6 %; respectively). These treatment responses did not differ (P ≥ 0.18) in cows with BCS ≥ 5.0. Collectively, results indicate that treatment with PG2 increased pregnancy per FTAI in B. indicus cows deficient in body energy reserves, by enhancing follicle development and estrous synchronization response.

Pregnancy rates of acyclic embryo surrogate mares synchronized with an intravaginal progesterone-releasing device (IPRD) and long-acting progesterone (LA-P4)

Pregnancy rates of acyclic embryo surrogate mares synchronized with an intravaginal progesterone-releasing device (IPRD) and long-acting progesterone (LA-P4)