Mg Of PGF2α Research Articles

The effect of prostaglandin and gonadotrophins (GnRH and hCG) injection combined with the ram effect on progesterone concentrations and reproductive performance of Karakul ewes during the non-breeding season.

The effect of prostaglandin and gonadotrophins (GnRH and hCG) combined with the ram effect on the progesterone (P4) concentrations and reproductive performance of Karakul ewes was investigated during non‐breeding season. Ewes (n = 93) received a male effect and were divided into two treatment groups including GnRH ‐ hCG (hCG, n = 32), GnRH ‐ GnRH (GnRH, n = 30) and a control (n = 31) group. This study was carried out from April (hormonal injection) to October (lambing). The first doses of GnRH (4.2 μg, Buserelin) were injected at the beginning of the study in treatment groups. These ewes were treated with hCG (250 IU) or the second GnRH dose five days later. All animals received two injections (ten days apart) of 150 μg PGF2α five days after the hCG or the second GnRH injection. Mating was initiated two days after the second prostaglandin injection and lasted for 34 days. Blood samples were collected by jugular venipuncture on days −10, −5, 0 (first PGF2α injection), 17 and 30 during the study. Pregnancy diagnosis was performed through transabdominal ultrasonography on day 40 after the removing of ram. Conception rate was 93.8, 90 and 87.1% in the hCG, GnRH and control groups, respectively. Lambing rate tended to increase in the hCG group compared with the control group (87.1 versus 58.1%; p < .1). There was no significant difference in P4 concentrations among studied groups in identical sampling times (p > .05). In conclusion, the administration of prostaglandin and hCG in combination with the ram effect tended to decrease lambing period. In other words this protocol tended to increase lambing rate at the first cycle. Treatment with hCG or GnRH did not increase serum P4 concentrations of treated Karakul ewes during the non‐breeding season.

Prostaglandin F2α influences pre-ovulatory follicle characteristics and pregnancy per AI in anovular dairy cows

Objectives were to determine the effects of a dose of PGF2α administered 2 days before timed artificial insemination (AI) on LH pulsatility, characteristics of the pre-ovulatory follicle, and pregnancy per artificial insemination (P/AI) in anovular dairy cows, particularly in cows not subjected to hyperthermia. In experiment 1, 2,011 lactating Holstein cows had ovaries scanned by ultrasound to determine corpus luteum (CL) presence and only those without a CL in two consecutive exams were enrolled (n = 437). Cows had the estrous cycle synchronized with an estradiol-progesterone based protocol starting on experiment Day −11 and timed AI on Day 0. Cows were assigned randomly to receive a single dose of 25 mg of PGF2α as dinoprost on Day −4 (1PGF, n = 222) or two doses of 25 mg each of PGF2α, one on Day −4 and one on Day −2 (2PGF, n = 215). Rectal temperatures were evaluated on the day of AI and 7 days later and cows were classified as being normothermic (<39.1 °C) or hyperthermic (≥39.1 °C). Ovulatory responses and P/AI were determined. In experiment 2, cows with regressed CL were exposed to low concentrations of progesterone and then randomly assigned to the same estrous synchronization protocol and treatments, 1PGF (n = 28) and 2PGF (n = 28). Blood was sampled and analyzed for concentrations of progesterone, and for concentrations of LH and 13,14-dihydro-15-keto-PGF2α metabolite (PGFM) every 15 min starting 1 h before to 6 h after treatments and then every 2 h from 12 to 59 h after treatments. The pre-ovulatory follicle was aspirated 44 h after treatments and concentrations of estradiol quantified. In experiment 1, treatment of anovular cows with a second dose of PGF2α increased P/AI in normothermic cows (19.8 [18/91] vs. 38.8% [31/80]), but not in hyperthermic cows. Synchronization was not affected by treatment, but it was greater for normothermic than hyperthermic cows (87.1 [149/171] vs. 77.8% [207/266]). When only synchronized cows were evaluated, the same responses were observed; treatment with 2PGF increased P/AI compared with 1PGF in normothermic cows (23.1 [18/78] vs. 43.7% [31/71]), but not in hyperthermic cows. In experiment 2, administration of 25 mg of dinoprost in 2PGF resulted in concentrations of PGFM 26-fold greater than 1PGF in the first 6 h after treatment (48 vs. 1,242 pg/mL). Cows receiving 2PGF had smaller basal LH concentration (0.57 vs. 0.46 ng/mL) and less frequent LH pulses (4.5 vs. 3.9 pulses/6 h), but duration of the LH surge was longer for 2PGF than 1PGF (13.1 vs. 15.5 h). Treatment with 2PGF increased the diameter and volume of the pre-ovulatory follicle, and concentration of estradiol (115 vs. 262 ng/mL) and total follicular estradiol content (124 vs. 505 ng) compared with 1PGF. Collectively, these results suggest that PGF2α has a role in fertility of anovular cows that is unrelated to its luteolytic effect.

Short communication: Heat stress does not affect induced luteolysis in Holstein cows

Heat stress (HS) has deleterious effects on bovine reproduction, including prolongation of the luteal phase in Holstein cows, perhaps due to compromised luteolysis. The objective was to characterize effects of HS on luteolytic responses of nonlactating Holstein cows given 25 or 12.5 mg of PGF2α on d 7 of the estrous cycle. Cows were randomly distributed into 2 environments: thermoneutral (n = 12; 25°C) or HS (n = 12; 36°C). In each environment, cows were treated with 2 mL of saline, 25 or 12.5 mg of PGF2α (n = 4 cows per group). The HS environment induced a significant increase in rectal temperature and respiratory rate compared with the thermoneutral environment. Heat stress did not have significant effects on luteolytic responses or circulating progesterone concentrations. Rapid and complete luteolysis occurred in all cows given 25 mg of PGF2α and in 4 of 8 cows given 12.5 mg; the other 4 cows given 12.5 mg had partial luteolysis, with circulating progesterone concentrations initially suppressed, but subsequently rebounding. Therefore, we conclude that HS does not change corpus luteum sensitivity to PGF2α.

Presynchronization with CIDR, with or without GnRH, prior to CO-Synch in beef heifers

Objectives were to compare ovarian responses and pregnancy per AI (P/AI) in Angus-cross beef heifers (n = 521; 4 locations) synchronized with CIDR–CO–Synch (CCOS) versus CIDR-GnRH–CO–Synch (CGCOS) protocols. Heifers were assigned a reproductive tract score (RTS: 1, immature, acyclic; 5, mature, cyclic), body condition score (BCS: 1, emaciated; 9, obese) and temperament score (0, calm, 1, excitable). Heifers in the CCOS (n = 261) group received a CIDR on Day −20 (removed on Day −13), 100 μg GnRH on Day −10, 25 mg PGF2α on Day −3 and were timed inseminated 60 h later, with concomitant GnRH (Day 0). Heifers in the CGCOS (n = 260) group received a CIDR on Day −26 (removed on Day −19), 100 μg of GnRH on days −16 and −10, 25 mg of PGF2α on Day −3 and were timed inseminated 60 h later, with concomitant GnRH (Day 0). Ovarian ultrasonography was done in a subset of heifers (n = 60; 30 in each group) to determine number and size of ovarian follicles and presence of corpus luteum (CL). There was increased (P < 0.05) percentage of heifers with CL in CGCOS group compared to heifers in CCOS group on Day −10 (82.3 vs 68.2%) and on Day −3 (88.3 vs 75.1%). Average size of the largest ovarian follicle on Day 0 was greater for heifers in CGCOS group compared to CCOS group (P < 0.05). However, P/AI did not differ between CCOS and CGCOS groups, 55.0% (143/260) and 59.8% (156/261), respectively (P > 0.1). In conclusion, CIDR presynchronization with or without GnRH (CCOS and CGCOS protocols) in beef heifers resulted in similar P/AI. Adding GnRH to presynchronization with CIDR resulted in more heifers with a CL at PGF2α and increased preovulatory follicle diameter at AI. Future studies are needed with bigger sample size and CIDR + CO-Synch treatment as control to determine economic benefit.

Intravaginal instillation of prostaglandin F2α was as effective as intramuscular injection for induction of luteal regression in lactating dairy cows

Our objectives were to test the efficacy of intravaginal (IVG) administration of PGF2α to induce corpus luteum (CL) regression, compare circulating progesterone (P4) profiles in cows receiving IVG versus intramuscular (IM) treatment with PGF2α, and evaluate reproductive outcomes. Lactating Holstein cows were synchronized using a Double-Ovsynch protocol [GnRH, 7 d later PGF2α, 3 d later GnRH, 7 d later GnRH, 7 d later PGF2α, 1 d later PGF2α, 32 h later GnRH, 16 to 20 h timed artificial insemination (TAI)] to receive TAI at 67 ± 3 d in milk. Seven days after the first GnRH treatment (time 0), cows with at least 1 visible CL ≥15 mm were blocked by parity and randomly assigned to a treatment that consisted of IM injection (IM-PGF; n = 201) or IVG instillation (IVG-PGF; n = 201) of PGF2α. Cows in IM-PGF received a single 25-mg dose of PGF2α (dinoprost tromethamine) intramuscularly. Cows in IVG-PGF received two 25-mg doses of PGF2α 12 h apart delivered through a catheter in the cranial portion of the vagina. Blood samples were collected at 0, 12, 48, and 72 h after treatment. Ovulation to the first GnRH of Double-Ovsynch was determined through transrectal ultrasonography. Only cows with P4 ≥1 ng/mL (functional CL) at time 0 (IM-PGF = 169; IVG-PGF = 179) were included in the analyses. Binary and quantitative data were analyzed by logistic regression and ANOVA with repeated measures, respectively. Results are presented as least squares means. Concentrations of P4 and the proportion of cows with a new CL at time 0 did not differ. Overall, the proportion of cows with CL regression using 1 ng of P4/mL (IM-PGF = 89.0%; IVG-PGF = 86.7%) or 0.5 ng of P4/mL (IM-PGF = 82.2%; IVG-PGF = 82.1%) as the cutoff did not differ. Concentrations of P4 were affected by treatment, time, and treatment × time interaction. Cows in IVG-PGF had greater mean P4 at 12 h than cows in IM-PGF. Mean P4 did not differ at 48 or 72 h after treatment. The proportion of cows with estrus recorded within 3 d of treatment (IM-PGF = 45.4%; IVG-PGF = 48.9%), ovulation risk after treatment (IM-PGF = 88.5%; IVG-PGF = 85.1%), and pregnancies per artificial insemination after TAI (IM-PGF = 51.5%; IVG-PGF = 57.8%) did not differ. We concluded that 2 IVG doses of 25 mg of PGF2α 12 h apart were as effective as a single 25-mg IM dose of PGF2α for inducing luteal regression in lactating dairy cattle.

PSXIII-40 Superovulation and oocyte recovery rates in CIDR synchronized goats treated with PGF2α, FSH and GnRH during breeding season

Abstract Embryo transfer is an advanced technology and has great potential in increasing desired livestock without physical boundaries. Multiple embryos can be produced in-vitro or in-vivo using semen from desired males. Early stage embryos (zygotes) are also ideal tools for genome-editing to alter the desired traits. However, the small number of mature oocytes produced each cycle is a major limitation of this technology. Scientists have used drugs to stimulate follicles to increase the number of oocytes/embryos. Extra oocytes/embryos produced can be cryopreserved or shipped to distant locations, to disseminate genetics around the world, at a fraction of cost. Embryos produced from superovulated animals can be transferred in recipient does, to produce desired number of animals. The goal of this study was to estimate the rate of ovulation and oocyte recovery after drug induced superovulation in goats. Eight cycling does were synchronized for estrus, using intravaginal CIDR dispensers, for 11 days during natural breeding season. Each doe was superovulated with a total of 200 mg of pFSH administered intramuscularly in 6 dosages (50 mg, 30 mg, and 20 mg given twice a day at 12 h interval) starting 48 h prior to CIDR removal. Each doe also received 8 mg of PGF2α, 24 h prior to CIDR removal, and 86 µg of GnRH 24 h after CIDR removal. The superovulatory response was evaluated by counting corpus luteum (CL) on each ovary after 48 h of GnRH injection. The ovulated oocytes were recovered surgically from oviducts by flushing with TL Hepes medium. Mean and standard deviation of CL calculated was 10.86±6.34 and 11.67±6.15 CL per doe (n = 8) in left and right ovaries, respectively. Similarly, mean and SD of mature oocytes recovered was 7.67±6.50 and 9.67±5.10 for left and right oviducts, respectively. Average percent recovery of oocytes was 71.23 % / doe.

Induction of synchronized multiple ovulation in dromedary camels during the early non-breeding season

Abstract The efficiency of two hormonal regimens on inducing synchronized multiple ovulation in camels at the beginning of the non-breeding season in Egypt was investigated. Twenty seven pluriparous camels, Camelus dromedarius, were used during April–May. Initially, each female retained a controlled intra-vaginal drug releaser (CIDR) for 13 consecutive days. One day before CIDRs withdrawal each camel received 750 μg PGF2α intramuscularly (i.m). Immediately after CIDRs removal (day 0), the camels were randomly divided into 3 groups of 9 animals each. The first group served as control (natural ovarian cycle), whereas females of the second and third groups were superovulated either by 2500 i.u eCG or 100 μg GnRH i.m, respectively. At peak ovarian activity (day 12), the females of each group were further divided into two subgroups, where induction of ovulation was carried out either by 5000 iu hCG or 20 μg GnRH i.m, respectively. Additionally, a set of blood samples was obtained from each camel at 0, 120, 150, 180, 210 and 240 min after ovulation induction to monitor incidence of LH surge, and ovulation was confirmed 72 h later by ovarian ultrasonography. The changes in reproductive hormones profiles, blood constituents and enzymatic activities throughout the period of the study were also determined. Total number of follicles, in all groups, recorded the lowest (P

Synchronization of GnRH and PGF2α on estrus response, pregnancy, progesterone hormones in crossing of Swamp Buffalo and Water Buffalo in West Sumatra, Indonesia

Abstract. Roza E, Aritonang SN, Susanti H, Sandra A. 2019. Synchronization of GnRH and PGF2α on estrus response, pregnancy, progesterone hormones in crossing of swamp buffalo and water buffalo in West Sumatra, Indonesia. Biodiversitas 20: 2910-2914. This study aims to determine the effect of GnRH and PGF2α synchronization on estrus emergence, pregnancy percentage, progesterone hormone levels and blood profile from artificial insemination (AI) of swamp and water buffalo crossing in Sijunjung, West Sumatra. The samples were 21 female swamp buffaloes with criteria clinically healthy, age ≥ 2.5 years and not pregnant. All buffalos on the first day were synchronized using 250 μgGnRH (Fertagyl®, Intervet International). All of the buffaloes received 12.5 μg PGF2α on the seventh day after GnRH injection. On the second day after injection of PG2α, the observation of estrus was carried out, the buffalos with estrus symptoms appeared after performing AI for 18 hours which the estrus symptoms was seen using a 0.5 ml Murrah buffalo semen with a sperm concentration of 500 million. Blood serum of 3-5 ml for the examination of progesterone levels was taken on days 21, 24, and 27 after appeared in AI. Hormone analysis was performed using the Enzyme-Linked Immunoabsorbent Assay (ELISA) method. The variables measured were the percentage of estrus, pregnancy, progesterone hormone levels, and blood profile. Pregnancy examination (PE) was carried out after 90 days in AI through rectal palpation. The data were analyzed descriptively. The results showed synchronization of GnRH and PG2α hormones in buffalo cattle which had 100% estrus, 66.67% pregnancy after AI, pregnant buffalo progesterone concentration 5.09-8.87 ng/mL and non-pregnant 1.11-3.45 ng/mL, total blood protein 7.9 g/L and blood glucose 86.86 mg/dL. The conclusion of this study is that the combination of GnRH and PG2α gives a clear appearance of estrus, progesterone hormone levels, and optimal buffalo blood profile.

Effect of manipulating progesterone before timed artificial insemination on reproductive and endocrine outcomes in high-producing multiparous Holstein cows

Our objective was to evaluate the effect of manipulating progesterone (P4) concentrations before timed artificial insemination (TAI) on reproductive and endocrine outcomes in high-producing Holstein cows. Multiparous lactating Holstein cows (n = 80) were synchronized for first TAI using a Double-Ovsynch protocol and were randomly assigned to receive 25 mg of PGF2α 1 d after the first GnRH treatment of the Breeding-Ovsynch protocol that included a once-used P4 insert (low-P4 group) or to receive 2 new P4 inserts during the Breeding-Ovsynch protocol (high-P4 group). Blood samples were collected thrice weekly from -10 to 32 d relative to TAI for all cows and from 32 to 67 d after TAI for pregnant cows and were analyzed for P4 and pregnancy-specific protein B (PSPB) concentrations. Expression of IFNτ-stimulated gene 15 (ISG15) was assessed in blood leukocytes 18 and 20 d after TAI. As expected, P4 concentrations were greater for high-P4 cows than for low-P4 cows from 3 to 8 d before TAI. Incidence of double ovulation was 3-fold greater for low-P4 cows than for high-P4 cows (33 vs. 10%), which resulted in more twin pregnancies 32 d after TAI for low-P4 cows than for high-P4 cows (29 vs. 0%). Low-P4 cows had larger preovulatory follicles at the last GnRH treatment of the Double-Ovsynch protocol and greater P4 concentrations than high-P4 cows after TAI. Relative expression of ISG15 mRNA 18 and 20 d after TAI was greater for low-P4 cows than for high-P4 cows and for pregnant cows than for nonpregnant cows. Overall, PSPB concentrations tended to be greater for low-P4 cows than for high-P4 cows, and pregnant cows had greater P4 concentrations than nonpregnant cows. In summary, cows with low P4 before TAI had increased preovulatory follicle diameter, PSPB concentrations, relative expression of ISG15 mRNA 18 and 20 d after TAI, double ovulations, and twinning compared with cows with high P4 before TAI. Increasing P4 before TAI may effectively decrease double ovulation and twinning in high-producing multiparous Holstein cows.

Evaluation of different hormonal treatments on oestral and ovarian responses in Moroccan Beni Arouss goats during anoestrus and breeding season.

The efficacy of eight combinations of fluorogestone acetate (FGA, 20 or 40mg as intravaginal device during 11days), equine chorionic gonadotropin (eCG, 300 or 500UI injected 48hr before FGA removal) and prostaglandin F2α (cloprostenol, 0 or 50μg injected 48hr before FGA removal) aiming at induction and synchronization of oestrus and ovulation was evaluated during the anoestrus season in spring and during the breeding season in autumn in adult Beni Arouss goats. Oestrous behaviour was recorded between 12 and 60hr after FGA removal. Blood samplings allowing to assess onset of the pre-ovulatory LH surge and increase of progesterone as sign of an active corpus luteum were performed, respectively, between 20 and 60hr and 3, 5, 8 and 15days after FGA removal. No season-related differences (spring vs. autumn) were observed for oestrous response (95% vs. 93%), pre-ovulatory LH surge (94% vs. 84%) and luteal response after 3-8 and 11-15days post-treatment (respectively 92% vs. 66% and 92% vs. 98%). The onset of oestrus (21 [13-53] vs. 32 [12-54]hr) and LH surge (26 [20-60] vs. 38 [22-60]hr) occurred significantly later in autumn. FGA (40 vs. 20mg) in autumn significantly delayed the onset of oestrus (36 [16-54] vs. 23 [12-47]hr) and LH surge (44 [26-58] vs. 33 [22-60]hr). Significant treatment-related differences were recorded for onset of LH surge (earliest for 20mg FGA, 300IU eCG, 50μg PGF2α ) and onset of luteal phase (latest for 40mg FGA, 300IU eCG, 50μg PGF2α ). In conclusion, the hormone combinations tested appeared equally effective in terms of oestrous and ovulation rates. Season has influenced significantly the onset of oestrus and LH surge, and the high dose regimen of FGA delayed the ovarian response in autumn.

PREVALENCE, DIAGNOSTICS AND TREATMENT OF OVARIAN FOLLICULAR CYSTS IN DAIRY COWS

Ovarian cysts are among the primary causes for poor reproduction efficiency and economic losses in dairy cattle farming. Material and metods: The studies were performed in 2015-2017 in three dairy cattle farms.In the experiment, 79 cows with follicular ovarian cysts were divided randomly into 3 groups. To the first group (n=33), a standard double Ovsynch was applied with 0.01 mg GnRH (Veterelin, Laboratorios Calier, Spain) on day 0, 150 µg PGF2α (D – Cloprosstenolsodium, Indupart, Vetpharma Animal Health, Spain) on day 7, 0.01 mg GnRH (Veterelin, Laboratorios Calier, Spain) on day 10, and after 7 days, Ovsynch (GnRH-PGF-GnRH). The cows from the second group (n=28) were submitted to double Ovsynch and additional progesterone treatment through placement of Controlled Internal Drug Release device (EAZI BREED CIDR Cattle insert, 1.38 g progesterone; Pfizer Animal Health, USA) for 7 days between the first GnRH at day 0 and prostaglandin on day 7. The control group comprised 18 untreated cows. Results: First-service conception rate in cows treated by double Ovsynch and vaginal inserts was higher 28.6% compared to that in standard double Ovsynch: 24.2%. Cumulative pregnancy percentage after applied treatments was 60.7% in double Ovsynch plus progesterone and 54.5% in standard double Ovsynch.

Eficiencia reproductiva de Ovsynch + CIDR en vacas Holstein bajo un esquema de inseminación artificial a tiempo fijo en el norte de México

Se evaluó el uso de Ovsynch más dispositivo intravaginal de liberación controlada de progesterona (CIDR) en vacas altas productoras. El estudio se llevó en la Comarca Lagunera (25° 44´ N, 103° 10´ O a 1,111 msnm) durante diciembre y enero. Las vacas (n=100) se pre-sincronizaron con dos inyecciones de PGF2α a los 35 y 47 días posparto y asignadas a dos tratamientos (n= 50): 1) El grupo OV recibió el protocolo Ovsynch: 100 μg de GnRH (i.m.; día 1), 25 mg de PGF2α (i.m.; día 7) y 100 μg GnRH (i.m.; día 9); 2) El grupo (OV+C) recibió el protocolo Ovsynch más un CIDR (1.38 g), retirado siete días después. Todas las vacas se expusieron a un protocolo de inseminación artificial a tiempo fijo (IATF; 16 a 20 h posteriores a la última inyección). Se registró tanto el porcentaje de preñez, el número de vacas repitiendo celo considerando dos periodos (≤24 y ≥25 días post-inseminación), así como los días de retorno al celo. Mientras que no existió diferencia entre grupos para tasa de preñez (OV= 28 %, OV+C= 32 %; P&gt;0.05), el porcentaje de vacas que manifestaron celo después de la IATF difirió (P&lt;0.05) entre tratamientos durante los dos periodos estudiados, 28 vs 62 % ≤24 días; 69 vs 35 % ≥25 días; OV y OV+C, respectivamente. El promedio de días en que repitieron celo fue menor (P&lt;0.05) en el OV+C (25 ± 1.6 vs 30 ± 1.3). El tratamiento Ovsynch+CIDR no mejoró la tasa de preñez; sin embargo, redujo la latencia en el retorno al celo, destacando como una alternativa para disminuir los días a la siguiente IA, y potencialmente para mejorar la eficiencia reproductiva y el retorno económico del hato lechero.

Administration of recombinant bovine somatotropin prior to fixed-time artificial insemination and the effects on fertility, embryo, and fetal size in beef heifers

Our objectives were to determine the effects of the administration of recombinant bovine somatotropin (bST) at the initiation of a fixed-time AI (TAI) protocol on concentrations of plasma IGF-1, follicle diameter, embryo/fetal size, and pregnancy rates in replacement beef heifers. Four hundred and fourteen Angus-based beef heifers were enrolled in a completely randomized design at 4 locations from January to July of 2016. All heifers were exposed to the 7-d CO-Synch + controlled internal drug release (CIDR) protocol where they received a 100-µg injection of GnRH and a CIDR insert on day -9, 25 mg of PGF2α at CIDR removal on day -2, followed by a 100-µg injection of GnRH and TAI 54 ± 2 h later on day 0. Within location, all heifers were randomly assigned to 1 of 2 treatments: 1) heifers that received 650 mg of bST on day -9 (BST; n = 191); or 2) heifers that did not receive bST on day -9 (CONTROL; n = 223). Blood samples were collected on day -9, 0, 28, and 60 to determine the plasma concentrations of IGF-1. Follicle diameter was determined on day -2 and 0 by transrectal ultrasonography. Pregnancy was diagnosed via transrectal ultrasonography on day 28 or 35, and again at least 30 d after the end of the breeding season. Embryo morphometry was assessed by measuring crown-to-rump length (CRL) on day 28, and fetal size was assessed by measuring crown-to-nose-length (CNL) on day 60. Concentrations of plasma IGF-1 did not differ between treatments on day -9 (P = 0.924), 28 (P = 0.075), and 60 (P = 0.792); however, concentrations of plasma IGF-1 were greater (P < 0.001) in BST-treated heifers at TAI (372.4 ± 16.6 vs. 193.7 ± 16.6 ng/ml). No differences (P = 0.191) were detected for follicle diameter between CONTROL and BST treatments on day -2 or 0. Pregnancy rates to TAI (PR/AI) were greater (P = 0.028) for CONTROL compared to BST heifers (42.5 ± 4.0 vs. 29.9 ± 4.1%). No differences (P = 0.536) in CRL were observed on day 28 between CONTROL and BST heifers. In addition, no difference (P = 0.890) was observed for CNL between CONTROL and BST treatments. Final pregnancy rates did not differ (P = 0.699) between treatments. The administration of bST to beef heifers at the initiation of a TAI protocol increased plasma concentrations of IGF-1 at TAI; however, failed to enhance follicle diameter, embryo/fetal size, and reduced PR/AI.

Prostaglandin F2α 7 d prior to initiation of the 7-d CO-synch + CIDR protocol failed to enhance estrus response and pregnancy rates in beef heifers.

To determine the effects of administration of 25 mg of PGF2α 7 d prior to the initiation of the 7-d CO-Synch + controlled internal drug release (CIDR) fixed-time AI (TAI) protocol, 985 Bos taurus beef heifers were enrolled in a completely randomized design at 9 locations from April to July of 2016. Within location, all heifers were randomly assigned to 1 of 2 treatments: 1) CONTROL (n = 496); 100 µg injection of GnRH and a CIDR insert for 7 d [day 7], administration of 25 mg of PGF2α at CIDR removal [day 0], followed by a second injection of GnRH and TAI 54 ± 2 h later; or 2) PRESYNCH (n = 489); same as CONTROL but heifers received an additional injection of 25 mg of PGF2α 7 d prior [day 14] to CIDR insertion. Estrous detection patches were applied to all heifers on day 14 and were evaluated for estrual activity on day 7. Similarly, estrus alert patches were placed on all heifers on day 0 and evaluated for estrual activity at the time of TAI. Pregnancy was diagnosed via transrectal ultrasonography between 35 and 55 d after TAI. The percentage of heifers exhibiting estrus between days 14 and 7 was greater (P < 0.001) for the PRESYNCH (70.1 ± 2.4%) than the CONTROL (41.1 ± 2.3%) treatment, whereas the percentage of heifers exhibiting estrus between day 0 and TAI was greater (P < 0.001) for the CONTROL (55.6 ± 2.4%) than the PRESYNCH (39.7 ± 2.5%) treatment. Estrus response rates differed (P < 0.001) among locations. Pregnancy rates to TAI differed (P = 0.023) among locations; however, they did not differ (P = 0.739) between CONTROL and PRESYNCH treatments (45.4 ± 2.5 vs. 43.2 ± 2.5%, respectively). Final breeding season pregnancy rates did not differ (P = 0.811) between treatments. Therefore, an injection of PGF2α 7 d prior to initiation of the 7-d CO-Synch + CIDR protocol failed to improve pregnancy rates to TAI in replacement beef heifers.

PREGNANCY RATE OF BUNAJI COWS IN A FIXED TIME AI SYNCHRONIZATION PROTOCOL USING OVATIDE

This study was aimed to access the reproductive performance of bunaji cows in an ovsynch protocol involving Ovatide. Bunaji cows (n=16) aged 4 – 6 years and weighing between 250 – 350kg were used. Selected cows with average body condition scores (BCS) of 2.5 – 3.5 using 0 – 5 scale from the most emaciated to the fattest. Cows were randomly assigned to 1 or 2 treatment groups for synchronization of ovulation. Treatment group 1 comprising Bunaji (n=8) received 50μg of GnRH (Cystorellin) and 25 mg of PGF2α. While, treatment group 2 comprising Bunaji (n=8) received 50μg of Ovatide and 25 mg of PGF2α. All cows from both treatment groups were inseminated at 16 hours after each second GnRH or Ovatide injections. Cows that showed mucus discharge from the vagina on the day of AI were recorded as well as those that had patent cervix. Cervical dilation was measured by taking note of the cows that had mid cervix insemination due to non‐passage of the AI gun through the cervix. Transrectal palpation was conducted twice at a month interval to select cycling cows within 5 to 12 days of the estrous cycle before initiating Ovsynch protocol. It was repeated on day 45 post – AI to confirm pregnancies in animals. Results showed that the rate of mucus discharge from the vagina and Cervical dilation for Ovatide were 37.5% and 87.5%; and GnRH (Cystorelin) 75% and 87.5% (P &gt; 0.05) and Pregnancy Rates were 0% and 12.5% respectively. There were no significant differences between the two groups. It was concluded that treatment of bunaji cows with 50μg Ovatide in Ovsynh protocol has heat induction potentials zero pregnancy rates. It was recommended that further studies be carried out using graded doses of 50μg, 100μg and 150μg of Ovatide in a fixed time AI synchronization protocol in bunaji cows.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Pregnancy rate in water buffalo following fixed-time artificial insemination using new or used intravaginal devices with two progesterone concentrations

This study evaluated the pregnancy rate (PR) after timed artificial insemination (TAI) in water buffalo (Bubalus bubalis) during both non-breeding and breeding season, using either a new or reused intravaginal device (IVD) with two different progesterone concentrations. A total of 247 dairy buffalo cows were randomly assigned using a two-by-three factorial design and four replicates to the following groups: (1) new intravaginal device (IVD-New: DIB®, 1.0g of P4, n = 51 or CIDR®, 1.38g of P4, n = 55); (2) intravaginal device previously used once (9days) (IVD-Used1x: DIB, n = 40 or CIDR, n = 51); or (3) intravaginal device previously used twice (18days) (IVD-Used2x: DIB, n = 27 or CIDR, n = 23). On day 0, animals received the IVD plus 10.5μg of buserelin acetate (GnRH) intramuscularly. On day 9, the devices were removed and 25mg of PGF2α plus 500IU of eCG was given intramuscularly. On day 11 (48h after IVD withdrawal), animals received 10.5μg of GnRH and were artificially inseminated 8-12h later. Data were analyzed using Proc Logistic of SAS®. Animals that received IVD-New-DIB, had a significantly higher PR (62.7%; P = 0.0193) compared to animals that received IVD-New-CIDR (40%). Pregnancy rate was not negatively affected by reusing both types of IVD. Overall PR (new and reused devices) was higher (P = 0.0055) in the DIB group (62.7%) compared to the CIDR group (45%). In conclusion, PR was higher in buffaloes treated with devices containing 1.0g of P4 (DIB®) compared to those receiving 1.38g of P4 (CIDR®). Reusing the intravaginal devices did not affect negatively PR/TAI, suggesting that P4 concentrations within the TAI protocols in water buffaloes could be reduced, without impairing their fertility.

Effect of dose and timing of prostaglandin F2α treatments during a Resynch protocol on luteal regression and fertility to timed artificial insemination in lactating Holstein cows

Our objective was to evaluate the effect of a second PGF2α treatment (25 mg of dinoprost) or a double dose of PGF2α (50 mg of dinoprost) during a Resynch protocol on luteal regression and pregnancies per artificial insemination (P/AI) in lactating dairy cows. Lactating Holstein cows (n = 1,100) were randomly assigned at a nonpregnancy diagnosis to receive (1) Ovsynch (control: 100 µg of GnRH; 7 d, 25 mg of PGF2α; 56 h, 100 µg of GnRH), (2) Ovsynch with a second PGF2α treatment (GPPG: 100 µg of GnRH; 7 d, 25 mg of PGF2α; 24 h, 25 mg of PGF2α; 32 h, 100 µg of GnRH), or (3) Ovsynch with a double dose of PGF2α (GDDP: 100 µg of GnRH; 7 d, 50 mg of PGF2α; 56 h, 100 µg of GnRH). All cows received timed artificial insemination (TAI) approximately 16 h after the second GnRH treatment (G2). Pregnancy diagnosis was performed by transrectal palpation 39 ± 3 d after TAI, and pregnancy status was reconfirmed 66 d after TAI. Blood samples collected from a subset of cows in each treatment at the first PGF2α treatment (n = 394) and at G2 (n = 367) were assayed for progesterone (P4). Data were analyzed by logistic regression using the GLIMMIX procedure of SAS (SAS Institute Inc., Cary, NC). At 39 d after TAI, GPPG cows tended to have more P/AI than control cows [35% (137/387) vs. 31% (107/349)], whereas P/AI for GDDP cows [32% (118/364)] did not differ from that for control cows. Pregnancy loss from 38 to 66 d did not differ among treatments and was 8% (30/362). The percentage of cows with complete luteal regression (P4 <0.4 ng/mL at G2) tended to differ among treatments and was greater for GPPG cows than for GDDP and control cows (94% vs. 88% vs. 88%, respectively). Overall, cows with P4 <1 ng/mL at the first PGF2α treatment had fewer P/AI than cows with P4 ≥1 ng/mL (27% vs. 38%), whereas cows with P4 ≥0.4 ng/mL at G2 had fewer P/AI than cows with P4 <0.4 ng/mL (15% vs. 38%). We conclude that adding a second PGF2α treatment 24 h after the first within a Resynch protocol tended to increase the proportion of cows undergoing complete luteal regression and P/AI, whereas treatment with a double dose of PGF2α at a single time did not.

Estrus synchronization and fixed-time artificial insemination alter calving distribution in Bos indicus influenced beef heifers

To determine the effects of estrus synchronization (ES) and fixed-time artificial insemination (TAI) on calving distribution in Bos indicus influenced heifers, 751 Bos taurus × Bos indicus beef heifers were enrolled in a completely randomized design at 2 locations from January to May of 2016. Within location, all heifers were randomly assigned to one of two treatments: 1) SYNCH (n = 371); heifers were exposed to the 5-day CO-Synch + CIDR protocol where they were treated with 100 μg of GnRH, 25 mg of PGF2α, and a controlled internal drug releasing insert (CIDR) on d 0; heifers received 50 mg of PGF2α at CIDR removal on d 5, and were treated with 100 μg of GnRH and TAI 66 ± 2 h later on d 8; or 2) CONTROL (n = 380); heifers were exposed to natural service without ES or TAI. On d 9, all heifers were exposed to bulls for the remainder of the breeding season at each location. Blood samples were collected on d −9 and on d 0 to determine pretreatment estrous cyclicity (progesterone ≥ 1.0 ng/mL). Pregnancy was diagnosed via transrectal ultrasonography 54 d after TAI by determining the presence of a viable fetus. Fetal age was estimated based on fetal size and structural features at the time of pregnancy diagnosis. Pregnancy rates on d 54 differed (P < 0.001) between locations, but did not differ (P = 0.777) between CONTROL and SYNCH treatments. Pregnancy rates on d 54 were greater (P < 0.001) in cycling compared with non-cycling heifers (63.9 vs 42.4%). A greater (P < 0.05) proportion of SYNCH heifers became pregnant in the first 19 d of the breeding season compared with CONTROL heifers (52.2 vs 46.4%). Overall breeding season pregnancy rates did not differ (P = 0.982) between treatments. In summary, ES and TAI increased the percentage of heifers that conceived in the first 19 d of the breeding season, and therefore, potentially altered the calving distribution by ensuring that more heifers calve early during the subsequent calving season.

Effect of GnRH on ovulatory response after luteolysis induced by two low doses of PGF2α in lactating dairy cows

This study investigated the effect of gonadotropin-releasing hormone (GnRH) on ovulatory response after complete luteolysis induced by two low doses of prostaglandin (PG)F2α in lactating dairy cows. Cows (n = 18) ranging between 45 and 65 days in milk were recruited for synchronization by a modified Ovsynch-48 protocol (GnRH-7 days-375 μg PGF2α-1 day-250 μg of PGF2α-1 day-GnRH) over a total of 23 estrous cycles. Synchronized cows (n = 16) were randomly assigned to GnRH and Saline groups in stage 1 of the experiment after 9–10 days of ovulation in synchronization. On days 0 and 1 (day 0 = first PGF2α administration), cows were treated with 375 and 250 μg PGF2α, respectively. On day 2, cows in the GnRH and Saline groups were administered 250 μg GnRH or 2.5 mL of 0.9% saline, respectively. Serum progesterone (P4) levels were measured and changes in the corpus luteum (CL) were ultrasonically monitored daily from day 0–3 to assess complete luteolysis. Preovulatory follicle diameter and ovulatory response were evaluated by ultrasonography. In stage 2, cows were treated in a manner converse to that in stage 1. The synchronization rate was 69.6% (16/23). In stages 1 and 2, cows showed complete luteolysis with P4 concentration <1 ng/mL or remaining CL area <50%. Average ovulation time was 29.3 ± 0.5 h, which mostly occurred between 28 and 30 h after GnRH injection. However, all cows in the Saline group ovulated later than 36 h post-injection, with an average time of 52.7 ± 8.6 h. There was no difference in preovulatory follicle diameter between the two groups (16.8 ± 0.5 and 17.3 ± 0.5 mm for GnRH and saline groups, respectively). Although ovulation rate was not correlated with treatment, the rate within 48 h of GnRH injection (93.3%) tended to be higher compared with that in the Saline group (60.0%). Thus, GnRH administration increased ovulation rate following complete luteolysis induced by two low doses of PGF2α. These results indicate that this simple protocol for dairy cows is an effective alternative to timed artificial insemination programs in the field.

470 Effects of eCG administration 4 versus 2 days prior to timed AI on Nellore cows

The objective of this study was to evaluate growth of the dominant follicle (DF) in multiparous Nellore cows treated with equine chorionic gonadotropin (eCG) either 4 or 2 d prior to timed AI (TAI). We hypothesized that early eCG administration improves follicular growth and increase DF diameter at TAI. Cows (n = 137) had their estrous cycle synchronized with an intravaginal device containing 1.9 g of progesterone (CIDR) and 2.0 mg of estradiol benzoate (d 0), 12.5 mg of PGF2α (d 7), CIDR withdrawal and 0.3 mg of estradiol cypionate (d 9), and TAI 48 h later (d 11). On d 7, ovaries were evaluated by ultrasonography and cows were blocked based on DF diameter (< 9 mm vs. ≥ 9 mm). Within block, cows were randomly assigned to receive 300 IU of eCG either on d 7 (eCGD7; n = 64) or on d 9 (eCGD9; n = 73). Diameter of the DF was evaluated by transrectal ultrasonography on d 7, 9, and 11. Follicular growth from d 7 to 9, 7 to 11, and 9 to 11 was analyzed by ANOVA using the GLIMMIX procedure of SAS. Follicular diameter was analyzed by ANOVA for repeated measures and cow was considered a random effect. Follicular growth from d 7 to 11 tended to be greater (P = 0.08) for eCGD7 compared with eCGD9 (4.9 ± 0.2 vs. 4.4 ± 0.2 mm). The overall effect of treatment was explained mostly by DF growth from d 7 to 9 (eCGD7 = 2.6 ± 0.2 vs. eCGD9 = 2.0 ± 0.2 mm; P < 0.01) as growth from d 9 to 11 did not differ (P = 0.44) between treatments (eCGD7 = 2.3 ± 0.2 vs. eCGD9 = 2.4 ± 0.1 mm). Follicular diameter was affected (P < 0.01) by the interaction between treatment and day. Whereas no difference was observed on d 7 (eCGD7 = 9.7 ± 0.2 vs. eCGD9 = 9.6 ± 0.2 mm), DF in eCGD7 cows was larger (P < 0.01) on d 9 (12.3 ± 0.2 vs. 11.5 ± 0.2 mm). In addition, DF on d 11 did not differ (P = 0.12) between treatments (eCGD7 = 14.5 ± 0.3 vs. eCGD9 = 14.0. ± 0.2 mm). Treatment with 300 IU of eCG 4 d prior to TAI improved follicular growth but did not increase overall mean of DF diameter at TAI compared with eCG administration 2 d before TAI in Nellore cows.