CIDR Removal Research Articles

5d CIDR-Heatsynch improves the circulatory estradiol levels, estrus expression and conception rate in anestrus buffalo (Bubalus bubalis)

The present study aimed to investigate whether increasing estradiol (E2) during preovulatory period would increase estrous expression, luteal profiles and conception rate in 5d CIDR based timed AI protocol. A total 156 anestrus buffalo allocated (78 per group) to either 5d CIDR-Cosynch (d-5: CIDR + GnRH; d0: PGF2α+CIDR removal; 72 h post-CIDR removal: GnRH) or 5d CIDR-Heatsynch (d-5: CIDR + GnRH; d0: PGF2α+CIDR removal; 24 h post-CIDR removal: estradiol benzoate) group. All the buffaloes inseminated at 72 and 84 h post-CIDR removal. A subset of buffalo (n = 58) were subjected to examination of the follicle diameter and luteal profile during protocol, post-AI on days 5 and 12. The buffalo in 5d CIDR-Heatsynch had greater (p < .05) E2 concentrations, estrus induction and increasing trend (p < .08) for conception rate (57.7% vs. 43.6%) than 5d CIDR-Cosynch. The percentage of pregnant buffalo that exhibited estrus signs was greater (p < .01) in 5d CIDR-Heatsynch than 5d CIDR-Cosynch. Positive correlation (p < .01) was observed between POF and E2 concentrations; POF and CL diameter, CL diameter and P4 concentrations. Estrus response and P4 concentrations were indicators of probability of pregnancy. In conclusion, 5d CIDR-Heatsynch tended to improve conception rate. The estrus expression and P4 concentrations (d5 and 12 post-first-AI) is the indicator of probability of pregnancy in buffalo.

Resumption of postpartum reproductive cyclicity and pregnancy rates after treatment with CIDR plus PGF2 α in normally calved and retained fetal membranes affected water buffaloes

An experiment was conducted to compare the estrus induction response, estrus pattern, endometrial regeneration and pregnancy rates following treatment with CIDR plus PGF2 α between normally calved (NC) and retained fetal membranes (RFM) affected water buffaloes. A total of 32 water buffaloes including 16 treated for RFM and 16 NC were selected and divided into 4 groups as I and II, and III and IV respectively. Buffaloes of group I and III were dewormed with Albendazole followed by the administration of mineral mixture in feed for 15 days. Buffaloes of all the groups were treated with CIDR intravaginally for 9 days and they received PGF2 α at 24 hours prior to CIDR withdrawal. After CIDR removal, the buffaloes of all the groups were artificially inseminated during induced estrus. Those buffaloes returned to estrus following breeding at induced estrus, were artificially inseminated twice at an interval of 24 hours. The estrus response following CIDR withdrawal was 100%. The RFM affected buffaloes had significantly longer interval to onset of estrus and shorter duration of estrus than NC buffaloes. More pronounced intensity of estrus following CIDR treatment was observed in NC buffaloes than in RFM affected buffaloes. The mean pregnancy rates obtained in NC and RFM affected buffaloes were 81.25% and 50%. Complete loss of epithelial layer, degenerative changes of endometrium and atrophic changes in the endometrial glands were observed in RFM affected buffaloes before estrus induction. After treatment, RFM affected buffaloes showed clear regeneration of endometrium and its glandular acini. It is concluded that estrus induction using CIDR plus PGF2 α might help to augment the fertility in NC and RFM affected buffaloes at field level.

292 Evaluation of two Beef cow Fixed-Time AI Protocols That Utilize pre-Synchronization

Abstract Pre-synchronization has been evaluated as a method to improve synchrony of ovulatory follicles before fixed-time AI (FTAI). The objective was to compare FTAI results in beef cows from two protocols that utilize pre-synchronization. Blood samples were collected on d-14 (d0=CIDR removal) to determine progesterone concentration at the start of synchronization (P4start: ≥1ng/mL=high, &amp;lt; 1ng/mL=low). In a subset (n=1,032), an additional blood sample was taken between d-21 and -29 to determine cyclicity. Cows (n=1,119), from 21 herds, were grouped by days postpartum and age and randomly assigned to one of two protocols. Cows assigned to the PG 6-day CIDR protocol (PG6d) received prostaglandin F2α (PG) on d-9, CIDR insertion and GnRH on d-6, and CIDR removal and PG on d0. Cows assigned to the 7&amp;7 Synch protocol (7&amp;7) were administered PG and CIDR insertion on d-14, GnRH on d-7, CIDR removal and PG on d0. For both protocols, FTAI occurred coincident with GnRH 66 h after second PG. Pregnancy was determined by transrectal ultrasonography 30-40 d following FTAI. The GLIMMIX procedure of SAS (9.4) was used to detect differences in estrus response and pregnancy success with herd included as a random variable. Estrus response (0 to 66 h) was influenced by treatment (P&amp;lt; 0.01; PG6d=60±5% and 7&amp;7=74±4%), Body Condition Score (P&amp;lt; 0.01), cycling status (P=0.03), P4start (P&amp;lt; 0.01), and a P4start by treatment interaction (P&amp;lt; 0.001; PG6d-highP4=62±6%, PG6d-lowP4=58±6%, 7&amp;7-highP4=84±3%, 7&amp;7-lowP4=60±6%). Pregnancy success was influenced by estrus expression (P&amp;lt; 0.01; estrus=38±4% and no estrus=62±6%), and a treatment by P4start interaction (P=0.04; PG6d-highP4=58±5%, PG6d-lowP4=39±7%, 7&amp;7-highP4=49±5%, 7&amp;7-lowP4=55±8%) but was not influenced by treatment (P=0.45; PG6d=49±4% and 7&amp;7=52±4%). In conclusion, effectiveness of pre-synchronization method depends on a cows’ physiological status at the beginning of the protocol. The 7&amp;7 protocol increased estrus response compared to PG6d, but there was no difference in pregnancy success.

291 Synchronization and Seasonality Effects on Follicular Development, Estrus Expression, and Pregnancy in Brahman Females

Abstract Control of follicular development is essential for estrous synchronization. This experiment determined differences in follicular development during synchronization in Brahman females. Cows (n=219) and heifers (n=90) in Fall (n=170) and Spring (n=139) were synchronized with a CIDR insert and administration of GnRH or PG treatment on d0 (1/2GnRH: n=106, GnRH: n=103, PG: n=100), and CIDR removal and PG administration on d6 followed by estrus detection and AI for 96h. Blood samples were collected on d0, d6, and d8 and/or AI to determine circulating progesterone (P4) concentrations. Transrectal ovarian ultrasonography occurred daily. Cows were grouped by CL presence (d0CL, d6CL) and P4 concentrations (d0P4, d6P4, d8P4, Low&amp;lt; 1 ng/mL, High≥1 ng/mL) on d0 and d6. The GLIMMIX procedure of SAS was used to analyze follicular wave initiation, wave emergence day, estrus expression, and pregnancy success. There were significant interactions of treatment by d0CL (P=0.0237), and season by d0P4 (P=0.0118) on wave initiation. Cows receiving 1/2GnRH with a CL on d0 (97±2%) and Fall cows having High d0P4 (96±3%) had the greatest probability of wave initiation. Age significantly impacted wave initiation (P=0.0213; heifers: 93±4%, cows: 79±5%). Interactions of treatment by season (P=0.0405) and treatment by d0CL (P=0.0379) significantly impacted wave emergence timing. Season (P&amp;lt; 0.0001; Fall: 23±5%, Spring: 65±6%), and the interactions of treatment by d0P4 (P=0.0291) and new wave by d0P4 (P=0.0357) influenced estrus expression. Cows receiving 1/2GnRH with High d0P4 and cows with High d0P4 that initiated a new wave had the greatest probability of estrus expression. Pregnancy rate differed by estrus expression (P=0.0055; no estrus=25±6%, estrus=54±8%) and semen type (P=0.0105; conventional=52±9%, sexed=26±6%), and tended to differ by d8P4 (P=0.0570; Low=30±7%, High=48±8%). These results suggest that differences in follicular development and behavioral estrus in synchronized Brahman females may be due to seasonality and endogenous progesterone production.

PSI-5 Comparison of 7&amp;7 Synch and 7-day Co-Synch + Cidr Protocols in a Fixed-Time ai System on Beef Cows Using Y-Sorted sex-Selected Semen

Abstract The 7&amp;7 Synch and the 7-day CO-Synch+CIDR fixed-time estrous synchronization protocols were compared among mature and two-year-old lactating postpartum Angus and SimAngus cows (n=201). Mature (n=63) and two-year-old (n=36) cows treated with the 7&amp;7 Synch received an injection of prostaglandin F2α (PGF; 25 mg dinoprost tromethamine) at the same time as insertion of an intravaginal progesterone-releasing insert (CIDR; 1.38g progesterone) on Day -17, gonadotrophin-releasing hormone (GnRH; 100 μg gonadorelin) on Day -10, and PGF at time of CIDR removal on Day -3. Mature (n=65) and two-year-old (n=37) cows in the 7-day CO-Synch+CIDR groups received an injection of GnRH on Day -10 that coincided with CIDR insertion and received PGF at the time of CIDR removal on Day -3. Fixed-timed AI (FTAI) by a single technician using Y-chromosome-bearing sex-sorted semen (4x106 sperm/unit of SexedULTRA 4M) from one of two Charolais bulls occurred on Day 0, 70 hours after PGF injection. Seven days later bulls were pastured with cows for the remainder of the breeding season. Transrectal ultrasound was performed 77-83 days after AI and fetal size was used to differentiate AI and natural service pregnancies. Within the mature cows and two-year-old age groups, the GLIMMIX procedure in SAS was used to compare FTAI and breeding season pregnancy rates with estrous synchronization treatment and sire as main effects. No differences (P=0.41) were observed amongst mature cows in FTAI pregnancy rates between the 7&amp;7 Synch (52.4%) and the 7-day CO-Synch+CIDR (44.9%) treatments. A greater (P=0.05) proportion of two-year-old cows were pregnant to FTAI following treatment with the 7-day CO-Synch+CIDR (56.7%) as compared to the 7&amp;7 Synch (33.4%). A greater (P=0.02) proportion of two-year-old cows in the 7-day CO-Synch+CIDR treatment (91.9%) were pregnant at the conclusion of the breeding season as compared with the 7&amp;7 Synch (69.7%).

PSIII-5 Evaluation of Gnrh Administration day in the 7 &amp; 7 Synch Protocol for Fixed-Timed Artificial Insemination in Multiparous Beef Cows

Abstract The objective was to determine the effects of a decreased interval of progesterone on the ovulatory follicle prior to fixed-timed artificial insemination (FTAI) in a 7 &amp; 7 Synch estrous synchronization protocol using estrus expression (EE), FTAI pregnancy rates (AIPR) on 37±2d, and overall pregnancy rates (OPR) after a 60d bull exposure 90±2d determined via ultrasound. Using conventional Angus semen, multiparous Angus-cross cows (n=201) from two locations were randomized by age and days post-partum into two treatments. Both treatments used a controlled internal drug releasing device (Eazi-breedTM CIDR; 1.38g progesterone) inserted intravaginally –14d of the protocol simultaneous to administration of prostaglandin F2α (PGF; 500µg cloprostenol sodium; Estrumate®). In the first treatment (7&amp;7), gonadotropin-releasing hormone (GnRH; 86µg gonadorelin; Fertagyl®) was administered on –7d. In the second treatment (8&amp;6), GnRH was administered on –6d. Both treatments were then administered PGF simultaneous to CIDR removal on 0d, 66±2h prior to FTAI and administration of GnRH. EE was determined at the time of artificial insemination using an EstrotectTM patch (Rockway Inc., Spring Valley, WI). EE was signified as a patch with 50% or more of the color rubbed off or missing. Subsequently, a patch with less than 50% of the color rubbed off, was not. AIPR, OPR and EE were analyzed by treatment using the GLIMMIX procedure on SAS 9.4 (SAS Institute Inc., Cary, NC.). There was a significant effect on EE (P=0.01), a tendency on PR (P=0.08), and no effect on OPR (P=0.53) by treatment. EE, AIPR, and OPR for 7&amp;7 were 95±2.1%, 82±3.7% and 96.7±1.7% and for 8&amp;6 were 86±4.0%, 91±3.1% and 98±1.5%, respectively. In conclusion, the altered timeframe of GnRH administration affected EE and tended to affect PR in multiparous beef cows, suggesting that GnRH administration may improve PR when administered 6d, instead of 7d, prior to CIDR removal.

Type of CIDR but not eCG administration affected pregnancy per AI in Holstein heifers subjected to a 5-day estrus synchronization protocol

ABSTRACT This study compared the effects of CIDR type and eCG treatment on ovarian follicular dynamics, estrus response and pregnancy per AI (P/AI) in Holstein heifers subjected to a 5-d estrus synchronization protocol. On Day 0, heifers (n = 133) received either a new or a once-used CIDR. On Day 5, CIDR was removed, 500 μg cloprostenol administered and heifers received or not 300 IU eCG (2 × 2 design). Heifers in estrus were inseminated 12 h after first observation. All heifers without estrus by 84 h after CIDR removal received 100 μg GnRH concurrently with AI. Ultrasonography was done in a subset of 77 heifers at CIDR insertion and removal, at AI and every 12 h after AI to determine follicular dynamics. Diameter of largest follicle at CIDR removal and AI was larger in heifers given a used CIDR (P < .05). The overall estrus response and ovulation (85.0 and 95.5%) did not differ between CIDR types, heifers given a new CIDR had greater P/AI (67.2 vs. 42.6%; P = .004). In summary, P/AI was reduced in dairy heifers treated with a used CIDR, despite having larger preovulatory follicles at AI. In addition, eCG treatment did not affect follicular dynamics, estrus response nor P/AI.

The response of blood plasma metabolite concentrations of anestrus lactating buffalo to CIDR-eCG with or without melatonin treatment

The objective of this study was to compare the efficiency of CIDR-eCG protocol with or without melatonin treatment on blood plasma metabolites in anestrus Murrah buffaloes during out-of-breeding season. Twelve lactating Murrah buffaloes were allotted to control and treated groups each of six animals. Treated buffaloes were implanted with melatonin (18 mg melatonin / 50 kg body weight) for 45 days, then animals of both groups received CIDR for 9 days. All animals received 500 IU eCG intramuscularly one day before CIDR removal and 10 µg GnRH on the day of AI. The animals were subjected to estrus detection daily as per farm routine. At weekly intervals, blood samples were collected to determine the concentration of blood plasma metabolites over 84 days’ period between June and September. All buffaloes exhibited estrus after CIDR removal. CIDR-eCG preceded with melatonin treatment increased plasma total protein, albumin, cholesterol and HDL-cholesterol (P&lt;0.05) in comparison to only CIDR treated control. Buffaloes treated with melatonin plus CIDR exhibited increased (P&lt;0.01) plasma glucose on days 28, 53 and 55 and reduction (P&lt;0.01) in HDL and AST at time of pregnancy diagnosis, while plasma concentration of phosphorus was the highest (P&lt;0.05) at day 84. In conclusion, CIDR-eCG treatment preceded with melatonin implantation improved reproductive performance and altered blood metabolite composition of lactating buffaloes during out-of-breeding season as compared to CIDR-eCG only.

Effect of PGF2α and GnRH administration on reproductive performance in Ghezel ewes

The main aim of the current study was to evaluate the effect of GnRH administration on day five after mating as well as PGF2α injection at the time of CIDR removal on the reproductive performance of Ghezel ewes. Estrus synchronization was performed using an intravaginal application of CIDR for 14 days and injection of 500 IU of PMSG at the time of CIDR removal. A total of 114 healthy fat-tailed ewes were randomly allotted into three groups as follow: control group (n = 35), did not receive any additional treatment; PG group (n = 44), each ewe received a dose of PGF2α at the time of CIDR removal; and PG+GnRH group (n = 35), the ewes received a dose of PGF2α at the time of CIDR removal and a single dose of GnRH, five days post-mating (post-conceptional day (PCD)− 5). Body condition score (BCS) of total ewes was determined at the time of CIDR insert. Blood samples were collected on PCD-19 for determining the serum progesterone levels. All the ewes were examined by transrectal ultrasonography 30–35 days after mating for pregnancy diagnosis. The serum values for P4 concentration were in control, PG and PG+GnRH groups 6.34 ± 1.17, 9.19 ± 2.55 and 10.57 ± 2.0 ng/mL respectively. The PG+GnRH treatment significantly increased the litter size compared to the control group (P = 0.04), but there were no significant differences in another reproductive indices between experimental groups. The multiple birth, twin, fecundity rates and litter size (P = 0.05, p = 0.03 and p = 0.003 respectively) were significantly higher in ewes with BCS > 2 compared to ewes with BCS ≤ 2. It is concluded that GnRH on PCD-5 treatment in addition to PGF2α injection at the time of CIDR removal could improve reproductive performance of Qezel ewes during non-breeding season.

8 Efficacy of Sequential Estrus Synchronization and Timed Artificial Insemination Protocols in Beef Cattle

Abstract The objective of this study was to assess the efficacy of sequential estrous synchronization and timed artificial insemination (TAI) in beef cattle using transrectal ultrasonography (US) for pregnancy diagnosis 26d after the initial TAI (TAI-1;d0) to determine pregnancy status and eligibility for the second TAI (TAI-2) on d 29. Angus and angus cross primiparous and multiparous cows were randomly assigned to one of two treatment regimens; either single TAI (CON; n = 468) or two sequential TAI (RS; n = 473). Estrus was synchronized for both treatment groups using the 7-day CO-synch + CIDR protocol forTAI-1 at 60h - 66h post- Prostaglandin injection (PGf2α). A second 7-day CO-synch + CIDR protocol was initiated for RS groups on d 19 and pregnancy status determined by US coincident with CIDR removal on d 26 post TAI-1. Non-pregnant RS cows received an injection of PGf2α and Estrotect® estrous detection aid was applied. All non-pregnant cows received a second TAI (TAI-2) and GnRH injection 60-66h after PGf2α (day 29). The probability of pregnancy at 30d post TAI-2 was higher (P &amp;lt; 0.01) for RS (82%) than CON cows (56%). Overall pregnancy rate on d 120 post TAI-1 did not differ between treatments (92%; P &amp;lt; 0.823). The probability of pregnancy to AI on d 120 was higher (P &amp;lt; 0.0001) for RS (78%) than CON cows (50%). Conversely, the probability of pregnancy sired by natural service was higher (P &amp;lt; 0.03) for CON (41%) than RS (15%) by design. Mean fetal age at 120d pregnancy diagnosis did not differ (P &amp;lt; 0.5547) between treatments (RS, 94 days; CON ,96 days). In conclusion, re-synchronization for a second TAI beginning 19 d after the initial TAI increased total AI-sired pregnancies and has the potential to reduce the required number of natural service sires without negatively influencing calving distribution.

Fertility Response Following Estradoublesynch and Progesterone Based Ovsynch Protocols in Delayed Pubertal Buffalo Heifers

The study evaluated the fertility response following Estradoublesynch and progesterone-based Ovsynch protocols in delayed pubertal buffalo heifers. A total of twenty delayed pubertal buffalo heifers were subdivided in two equal subgroups. Group I animals were treated with PGF2α analogue (500 µg cloprostenol sodium) i.m. on day 0, GnRH analogue (20 µg buserelin acetate) on day 2, PGF2α analogue (500 µg cloprostenol sodium) repeated on day 9 and estradiol benzoate 1 mg intramuscular (i.m.) on day 10. Fixed-time artificial insemination (FTAI) was done at 48 and 60h. Group II animals were subjected to GnRH analogue (20 µg buserelin acetate) i.m. along with CIDR insert intravaginally on day 0, PGF2α analogue (500 µg cloprostenol sodium) i.m. and removal of CIDR on day 7, GnRH analogue on day 9 followed by FTAI at 12 and 24h. Blood collection (plasma P4) and ultrasonography (luteal and follicular dynamics) was performed on day 0, 9, 10, 12 in group I and day 0, 7, 9 and 10 in group II animals. Pregnancy diagnosis was made at 45-60 days post AI. Estrus response was observed in all the buffalo heifers of group I and II. First service conception rate was significantly higher in group I (50%) compared to group II (20%) (P&lt;0.05). Overall pregnancy rate was almost similar in both group I and II (60% vs 70%). In conclusion, estradoublesynch and progesterone-based ovsynch protocol can effectively induce ovulatory estrus and improve pregnancy rates in delayed pubertal buffalo heifers.

Uso del CIDR y cipionato de estradiol en protocolos de sincronización sobre la presentación de celo, tasa de preñez y natalidad en borregas criollas bajo condiciones de altura

The objective of this research was to evaluate the use of the intravaginal device (CIDR) and estradiol cypionate in synchronization protocols, on oestrus presentation, pregnancy and birth rate in Creole sheep under high altitude conditions. The study was carried out in a non-reproductive season, in the peruvian highlands, using 57 ewes. Four experimental groups were formed: group T1 (n=14) and T3 (n=14), CIDR progesterone device for 7 days and 12 days, respectively; group T2 (n=15) and T4 (n=14), CIDR progesterone device for 7 days and 12 days plus 1 mg of estradiol cypionate, 24 hours after removal of the device in both groups, respectively. Estrous presentation was observed from CIDR removal to 48 hours using vasectomized rams and IATF was performed with fresh semen 48 hours after device removal. The pregnancy rate was determined by ultrasonography at 46 and 90 days after FTAI and the birth rate was recorded. The chi-square test was used for statistical analysis. There was no difference (P&gt;0.05) between groups, for estrous presentation, but there was difference (P&lt;0.05) for pregnancy rate at 46 days between groups with: T1 (42.9%), T3 (38.5%), T4 (21.4%), with respect to T2 (0%) (The difference in results are shown in Table 2). There was a difference (P&lt;0.05) for the pregnancy rate at 90 days: T1 (35.7%) and T3 (30.8%), with respect to T4 (7.1%) and T2 (0 %). The birth rate showed differences (P&lt;0.05) for T1 (28.6%) and T3 (28.6%), with respect to T2 (0%) and T4 (0%). In conclusion, a high pregnancy rate was obtained with CIDR for 7 and 12 days, compared to the use of CIDR plus estradiol cypionate. However, no births were obtained with progesterone plus estradiol cypionate treatment.

Evaluation of the 7 & 7 Synch and 7-day CO-Synch + CIDR treatment regimens for control of the estrous cycle among beef cows prior to fixed-time artificial insemination with conventional or sex-sorted semen

An experiment was conducted to compare the 7 & 7 Synch and 7-day CO-Synch + controlled internal drug release (CIDR®) treatment regimens before fixed-time artificial insemination (FTAI) of beef cows with conventional or sex-sorted semen. Cows (n = 1538) were blocked based on age and days postpartum (DPP) and randomly assigned to treatment regimen and semen type. Cows assigned to the 7-day CO-Synch + CIDR treatment regimen (n = 769) were administered gonadotropin-releasing hormone (GnRH) and an intravaginal progesterone-releasing insert (CIDR) on Day − 10, and administration of prostaglandin F2α (PG) coincident with CIDR removal on Day − 3. Cows assigned to 7 & 7 Synch (n = 769) were administered PG and a CIDR device on Day − 17, GnRH on Day − 10, and PG coincident with CIDR removal on Day − 3. Cows were administered GnRH coincident with FTAI, which was performed 66 h after CIDR removal with conventional (20 × 106 cells) or sex-sorted (4 × 106 cells) semen. Expression of estrus was affected by treatment regimen (P = 0.01) and by treatment regimen × DPP (P = 0.0004), as a result of imposing the 7 & 7 Synch regimen; therefore, a greater percentage of cows expressed estrus (82% compared with 64%), particularly among cows with greater DPP. Pregnancy percentages resulting from FTAI were less (P < 0.0001) when using sex-sorted semen but greater among cows treated with 7 & 7 Synch (conventional semen: 72%; sex-sorted semen: 52%) compared with 7-day CO-Synch + CIDR (conventional semen: 61%; sex-sorted semen: 44%).

Intrafollicular oocyte transfer (IFOT): Potential feasibility in the ovine species

Intra-follicular oocyte transfer (IFOT) is a promising and innovative technique for in vivo embryo production previously described for equines and bovines. The aim of this study was to assess the feasibility of IFOT in the ovine species. Two preliminary in vivo and in vitro trials were performed to test the optimal procedures and timing for IFOT. In the in vivo trial, follicular growth was monitored with transrectal ultrasonography in ten adult ewes to preliminarily determine the ovulation and ideal timing for IFOT. The in vitro trial assessed i) the optimal inner diameter of the injection needle and ii) the recovery rate and integrity of injected cumulus-oocyte complexes (COCs) after follicle aspiration. For IFOT and embryo collection, five ewes were synchronized by CIDR insertion. Forty hours after CIDR removal, in ewes under sedation and general anesthesia, the ovaries were exposed by laparotomy, and the preovulatory follicle was injected with COCs previously collected from ovaries obtained from an abattoir. At 4 h after surgery, fully recovered ewes were housed in a paddock with a ram of proven fertility. Crayon marking on ram's chest was used to detect mating. Ovulation was assessed 40 h after the transfer of oocytes by transrectal ultrasonography. On day 6 after IFOT, embryo collection was performed by uterine flushing. In the in vitro testing, injection of >5 mm follicles with a 28 G needle loaded with 30 COCs in a 5 μL volume resulted in higher recovery rates and better preservation of COCs integrity. In the in vivo trial, ultrasound scanning revealed that ovulation occurred between 60 and 72 h after CIDR removal in all animals. In one ewe subjected to IFOT, 22/24 oocytes were effectively injected into the preovulatory follicle, but no embryos were collected after flushing. In the remaining four animals, 85/102 oocytes were injected, and six cleaved embryos, 12 morulae and 1 blastocyst were collected, including native embryos. This preliminary investigation indicated that IFOT in ovine species resulted in ovulation, fimbrial capture, tubal transport of heterologous oocytes and in vivo embryo production. Further studies are needed to optimize the embryo recovery rate and develop less invasive techniques for oocyte injection and uterine flushing, such as through a laparoscopic or transcervical approach.

Efficiency of hCG for Inducing Resumption of Ovarian Cyclicity and Synchronized Ovulations during the Seasonal Anestrous in Sheep.

Simple SummaryThe use of equine chorionic gonadotrophin (eCG) in protocols for estrus synchronization in sheep is currently challenged, so it is necessary to implement alternatives (i.e., human chorionic gonadotropin; hCG), mainly during the anestrous season. Therefore, we compared the reproductive outcomes, including estrus induction, ovulatory follicle dynamics, and pregnancy outputs in anestrus Dorper sheep treated with insertion of one intravaginal progesterone-loaded CIDR + either saline, eCG, or hCG. The administration of hCG at the time of CIDR removal was effective at inducing estrus, resume ovulations, and ovarian cyclicity, yet, in a narrow window of time, it is a scenario that may limit the implementation of an artificial insemination protocol.This research aimed to evaluate whether the administration of hCG at the time of removal of a progesterone device may be effective at inducing estrus and ovulations in sheep during the natural seasonal anestrous, by comparing reproductive outputs (induction and duration of estrus, follicle development, ovulation, ovulation rate, and pregnancy rates) in ewes treated with eCG or only saline solution at the time of CIDR removal. Whereas results demonstrated no response in the control non-treated group, the largest rate of narrowly synchronized estrus signs and ovulations occurred in the eCG-group. The administration of hCG was effective at inducing estrus, promote follicular growth and a delayed yet significant ovulation (>84%) on day 10 after CIDR removal; moreover, an increased embryonic implantation rate was also observed. Moreover, if the hCG ewes remain exposed to active males for some days, said strategy could be adopted, aiming to induce pregnancies by natural mating in a short period of time.

PSI-7 Comparison of 6-day versus 7-day CIDR protocol with GnRH and PGFα to synchronize crossbred beef cows for fixed-timed ai with sexed semen at two different times

Abstract Preliminary data indicate that shortening the progesterone exposure with CIDR can improve conception rates compared to the established 7-day CO-Synch protocols. The objective was to determine the effects of shortening progesterone exposure from 7 days to 6 days among crossbred beef cows and fixed-time artificial insemination (FTAI) with sex-sorted semen. A total of 147 fall calving (September-November) crossbred beef cows from one location were randomized to one of four treatments: 1 and 4) 7-d CO-Synch + CIDR protocol with administration of gonadotropin-releasing hormone (GnRH) and a CIDR insert on day 0, prostaglandin F2α (PGF) at CIDR removal on day 7, and FTAI occurring 66 h (Treatment 1) or 74 h (Treatment 4) later; 2 and 3) 6-d CO-Synch + CIDR protocol with administration of GnRH and CIDR insert on day 0, prostaglandin F2α (PGF) at CIDR removal on day 6, and FTAI occurring 72 h (Treatment 2) or 80 h (Treatment 3) later. Sex-sorted semen from Angus sires was used for AI. Pregnancy was determined by ultrasound 40 days after AI. Pregnancy rate was analyzed using the MIXED procedure of SAS with CIDR and AI service time as fixed effects. Chi-square analysis was used to assess the number of pregnant and open cows in each treatment using the FREQ procedure of SAS. There was no difference (P = 0.78) in pregnancy rates between 6-d CIDR (0.59 ± 0.05%) and 7 d CIDR (0.57 ± 0.05%) protocols. Cattle bred a shorter period after CIDR removal (0.64 ± 0.05%) had numerically (P = 0.11) greater pregnancy rates compared to those with a longer period after CIDR removal (0.51 ± 0.05%). There was no difference in the number of pregnant and open cows between treatment groups. These data suggest that using a 6-day or 7-day protocol, regardless of breeding time, results in similar conception rates.

PSV-3 Ovarian dynamics of brahman cows submitted to five-day or twelve-day progesterone-based estrus synchronization protocol

Abstract The aim of this study was to investigate the ovarian response of Brahman cows submitted to two different estrus synchronization protocols and to determine the estrus response and ovulation time. A total of 153 Brahman cows were randomly assigned to receive one of the following estrus synchronization protocols: 1) CIDR insert and an injection of prostaglandin F2α (25 mg, PGF) on Day -5 and CIDR removal with PGF on Day 0 (CIDR5; n = 77); 2) CIDR insert on Day -12 and an injection of PGF on Day -12, Day -5 and Day 0 upon CIDR removal (CIDR12; n = 76). Estrotect breeding indicator patches were placed on Day 0 and cows were artificially inseminated (AI) 12h after estrus detection; cows not detected in estrus after 96h received TAI coupled with 100 µg of GnRH. Ovarian dynamics were observed during the protocol and follicular diameter were measured every 12h after AI until ovulation. Cows synchronized with CIDR12 had increased follicular diameter (CIDR5, 10.19 ± 0.51 vs. CIDR12, 13.12 ± 0.52 mm; P = 0.01) and decreased serum concentrations of progesterone (CIDR5, 1.68 ± 0.12 vs. CIDR12, 0.81 ± 0.12 ng/ml; P &amp;lt; 0.01) at CIDR removal. The percentage of cows exhibiting estrus did not differ between treatments (CIDR5, 66.2 vs. CIDR12, 64.5%; P = 0.25). No difference was observed in ovulation rate (CIDR5, 94.1 vs. CIDR12, 94.1%; P = 0.6). Time of estrus expression and ovulation time after CIDR removal did not differ (CIDR5, 59.9 ± 2.3 vs. CIDR12, 61.5 ± 2.3h; P = 0.71 and CIDR5, 88.1 ± 2.6 vs. CIDR12, 90.9 ± 2.6h; P = 0.75; respectively). In conclusion, extended length of CIDR with additional PGF increased follicular diameter and decreased concentrations of progesterone but did not influence estrus response and ovulation time in Brahman cows.

PSXII-20 Ovarian dynamics and fertility in beef cows administered a 5-day or 6-day CO-Synch protocol for timed artificial insemination

Abstract The 5-day CO-Synch is an extensively used TAI protocol; however, it requires multiple administrations of prostaglandin F2α (PGF). The objective of the present study was to evaluate the effect of increasing progesterone (P4) device insertion from 5 to 6 days during a TAI protocol on ovarian dynamics and fertility in beef cows. Suckled beef cows (n = 867) at six locations were randomly assigned to either a 5-day or 6-day CO-Synch. Cows received an intravaginal P4 device (CIDR, Zoetis) and 100 µg of gonadorelin acetate (GnRH, Parnell) on d-9 (6-day) or d-8 (5-day). On d-3 CIDR’s were removed, an estrus detection patch applied (Estrotect, Rockway Inc.) and either one (6-day) or two (5-day) doses of PGF (500 µg of cloprostenol sodium, Estroplan, Parnell) was administered. On d0 (72 h after CIDR removal) all cows received 100 µg of GnRH, estrus expression was evaluated, and AI was performed. Pregnancy was determined by ultrasonography 34 days after TAI. Ovarian dynamics were evaluated in a subset of animals (n = 20) between d-3 and d7 to determine preovulatory follicle size, time of ovulation and corpus luteum (CL) size. Data were analyzed using generalized linear mixed models (SAS 9.4). Cows in the 6-day group tended (P = 0.09) to have a larger maximum follicle diameter (16.2±0.4mm) than cows in the 5-day group (15.0±0.6mm). In addition, CL volume on d7 was greater (P = 0.01) in the 6-day (4302±495mm3) than 5-day (2406±455mm3) group. There were, however, no differences (P = 0.15) in the interval between CIDR removal and ovulation. Cows assigned to the 6-day group had greater (P &amp;lt; 0.05) estrus expression [56.1% (215/385) vs 41.5% (161/388)] and pregnancy rate [54.6% (236/438) vs 47.4% (207/435)] than cows in the 5-day group. In conclusion, extension of the period of P4 device insertion in a prolonged proestrus protocol increases preovulatory follicle size, estrous expression, and fertility to TAI.

519 Late-Breaking: Evaluation of the 7 &amp; 7 Synch and Bee Synch II protocols for control of the estrous cycle among cows of varying percentage Bos indicus influence

Abstract The 7 &amp; 7 Synch and Bee Synch II protocols for control of the estrous cycle were compared among cows with varying percentages of Bos indicus influence. Angus (n = 48), ⅛ - ¼ Brahman-influenced (n = 90), Brangus (n = 11), and ½ Brahman-influenced (n = 56) cows were blocked based on breed, age, and days postpartum and randomly assigned to treatment. Cows treated with 7 &amp; 7 Synch (n = 104) received prostaglandin F2α (PG; 25 mg dinoprost tromethamine) and insertion of an intravaginal progesterone-releasing insert (CIDR; 1.38g progesterone) on Day -17, gonadotropin-releasing hormone (GnRH; 100 μg gonadorelin) on Day -10, and PG coincident with CIDR removal on Day -3. Cows treated with Bee Synch II (n = 101) received PG coincident with CIDR insertion on Day -8 and PG coincident with CIDR removal on Day -3. Fixed-time artificial insemination was performed on Day 0 at 66 h. Ovarian ultrasound was performed on Day -3 to assess presence of corpora lutea (CL) and diameter of the largest ovarian follicle (LFD), and color Doppler was used on Day 7 to assess CL blood perfusion. A greater proportion of 7 &amp; 7 Synch cows (P &amp;lt; 0.0001) had CL on Day -3 (83%; 86/104) compared with Bee Synch II cows (48%; 48/101). On Day -3, LFD did not differ among Bos indicus-influenced cows treated with Bee Synch II (12.5±0.3 mm), Bos indicus-influenced cows treated with 7 &amp; 7 Synch (12.2±0.3 mm), or Angus cows treated with 7 &amp; 7 Synch (12.1±0.6 mm); however, greater LFD was observed among Angus cows treated with Bee Synch II (15.4±0.8 mm). Brangus cows had greater periphery signal percentages (P = 0.02) when treated with 7 &amp; 7 Synch compared with Bee Synch II. In conclusion, across cow of varying percentage Bos indicus influence, 7 &amp; 7 Synch resulted in a greater proportion of cows with CL on Day -3.

PSXII-15 Evaluation of later timing of fixed-time artificial insemination for beef cows when using sex-sorted semen following the 7 &amp; 7 Synch protocol

Abstract An experiment was designed to evaluate later timing of fixed-time artificial insemination (FTAI) with sex-sorted semen among postpartum beef cows following the 7 &amp; 7 Synch protocol, with the hypothesis that later timing would result in increased pregnancy rates (P/AI) among cows that expressed estrus prior to FTAI. Beef cows (n = 414) were blocked based on age and days postpartum (DPP) and randomly assigned to receive FTAI at 66 or 72 h after administration of prostaglandin F2α (PG). Estrus was synchronized using the 7 &amp; 7 Synch protocol, which consists of administration of PG (500 μg cloprostenol) and insertion of an intravaginal progesterone-releasing insert (CIDR; 1.38 g progesterone) on Day 0, gonadotropin-releasing hormone (GnRH; 100 μg gonadorelin) on Day 7, and PG coincident with CIDR removal on Day 14. Estrus detection aids (EstrotectTM) were applied to all cows on Day 14, and activation status was recorded at fixed-time artificial insemination (FTAI) on Day 17. All cows that expressed estrus prior to FTAI received sex-sorted semen (4 × 106 cells per unit; SexedULTRA 4MTM). The proportion of cows expressing estrus prior to FTAI did not differ between treatments at this power of test [66 h: 71% (146/205); 72 h: 76% (158/209)]. Additionally, P/AI of estrous cows inseminated with sex-sorted semen did not differ between treatments [66 h: 44% (90/205); 72 h: 39% (82/209)]. In conclusion, later timing of FTAI following the 7 &amp; 7 Synch protocol failed to improve P/AI of estrous cows inseminated with sex-sorted semen.