Synchronization Regimen Research Articles

Factors influencing pregnancy rate and loss after laparoscopic artificial insemination with frozen-thawed semen in Lohi sheep under sub-tropical conditions.

This study evaluates factors influencing pregnancy rates per artificial insemination (P/AI) and pregnancy loss in Lohi ewes undergoing laparoscopic AI with frozen-thawed semen under sub-tropical conditions. Data from three experiments comprising ewes (n = 358) of mixed parity (nulliparous; NP and parous; P), various body condition score (BCS) and assigned to long-term (LTP, 11 days) and short-term (STP, 5 days) oestrus synchronization regimen across high breeding season (HBS) and low breeding season (LBS) were analysed. Laparoscopic insemination was conducted 54 h post-sponge removal. Pregnancy diagnosis and loss were evaluated on days 35 and 90 post-insemination via ultrasonography. Results showed parity significantly influenced P/AI, with nulliparous ewes achieving higher pregnancy ratios than parous ewes (p = .001). BCS significantly influenced P/AI (p < .05), with a quadratic relationship observed between BCS and season (BCS*BCS*Season; p = .07). Progestin treatment did not significantly influence the ratio of pregnant ewes (p = .07). Pregnancy losses were significantly higher during LBS than HBS (p < .05), irrespective of progestin treatment. In conclusion, parity and BCS significantly influenced P/AI, with BCS demonstrating a quadratic association with season. Ewes bred during LBS experienced higher pregnancy losses than HBS, irrespective of progestin treatment.

Incorporation of L-Carnitine in the OvSynch protocol enhances the morphometrical and hemodynamic parameters of the ovarian structures and uterus in ewes under summer climatic conditions

Heat stress negatively impacts the reproductive performance of sheep including the efficiency of estrous synchronization regimens. This study aimed to investigate the potential effects of L-Carnitine (LC) administration on the efficacy of the OvSynch protocol in ewes under summer climatic conditions. Ewes were synchronized for estrus using the OvSynch protocol and a dose of LC (20 mg/kg body weight) was intravenously (IV) administered on the same day of PGF2α injection to one group (n = 8; LC group), while other ewes (n = 8; control group) received the same protocol without LC. Ultrasonographic evaluation (including B-mode, color, and pulsed Doppler) was used to assess the morphometrical and hemodynamic parameters of ovarian structures [number, size, and blood flow of follicles (GFs) and corpora lutea (CLs)] and uterus during the estrous phase (Day 0), and on Day 8 post ovulation (luteal phase). Uterine artery blood flow (MUA) was assessed by measuring the resistive index (RI) and pulsatility index (PI) at both stages. The serum samples were collected to measure the concentrations of estradiol (E2), progesterone (P4), and total antioxidant capacity (TAC) using commercial kits. Results revealed a significant (P<0.05) increase in the colored pixel area of GFs and uterus in the LC group (392.84 ± 31.86 and 712.50 ± 46.88, respectively) compared to the control one (226.25 ± 17.74 and 322 ± 18.78, respectively) during Day 0. Circulating E2 and TAC levels were significantly (P<0.05) higher in the LC-treated ewes (31.45 ± 1.53 pg/ml and 1.80 ± 0.13 mM/L, respectively) compared to those in the control ewes (21.20 ± 1.30 pg/ml and 0.98 ± 0.09 mM/L, respectively) during Day 0. Moreover, LC improved the colored pixel area of CLs (2038.14 ± 102.94 versus 1098 ± 82.39) and uterus (256.38 ± 39.28 versus 121.75 ± 11.36) and circulating P4 (2.99 ± 0.26 ng/ml versus1.67 ± 0.15 ng/ml) on Day 8. Values of RI of MUA were significantly lower in the LC group compared to the control one on Day 0 and Day 8 (0.48 ± 0.03 versus 0.72 ± 0.03 and 0.58 ± 0.03 versus 0.78 ± 0.02, respectively). In conclusion, LC incorporation in the OvSynch protocol enhanced the morphometrical and hemodynamic parameters of the ovarian structures and the uterus concomitantly with improvements in the TAC, E2, and P4 concentrations in ewes under hot summer conditions.

Effect of Different Synchronization Regimens on Reproductive Variables of Crossbred (Swamp × Riverine) Nulliparous and Multiparous Buffaloes during Peak and Low Breeding Seasons.

Simple SummaryParity and season are two prominent variants which influence buffalo reproductive performance and synchronization outcome. The present study compared modified new Ovsynch synchronization (GPGMH) protocol with conventional Ovsynch (OVS) in reproductive parameters of buffaloes with different parity (nulliparous and multiparous) in different seasons (peak and low breeding seasons). Compared to the conventional Ovsynch, the modified GPGMH protocol was more effective to enhance the estrus rate, ovulation rate and pregnancy rate in multiparous crossbred buffaloes. In addition, the application of GPGMH protocol improve the reproductive performance during the peak breeding season than low breeding season.The present study was conducted to examine the effect of conventional the Ovsynch protocol (OVS) and a modified Ovsynch synchronization (GPGMH) protocol on the follicular dynamics, estrus, ovulation, and pregnancy in nulliparous and multiparous crossbred (swamp × riverine) buffaloes during different seasons. GPGMH or OVS protocols were used to synchronize nulliparous (n = 128; GPGMH = 94, OVS = 34) and multiparous (n = 154; GPGMH = 122, OVS = 32) buffaloes during the peak (n = 186; GPGMH = 143, OVS = 43) and low breeding (n = 96; GPGMH = 73, OVS = 23) seasons. Buffaloes were monitored for follicular dynamics, estrus response, ovulation, and pregnancy rates. The results showed that protocol, parity, and season had significant effects on estrus, ovulation, and pregnancy variables, and interactions among parity and protocol, season and protocol, and season and parity were observed for few of reproductive indices in the crossbred buffaloes. There were no significant (p > 0.05) interaction for protocol, parity and season. In multiparous buffaloes, the application of the GPGMH protocol significantly (p < 0.05) increased the interaction to the interval to estrus onset after the second GnRH, estrus response, ovulation rate, and pregnancy rate, and lowered (p < 0.05) the silent estrus when compared with the conventional OVS protocol. During the peak breeding season, the application of the GPGMH protocol significantly (p < 0.05) improved the interaction to the estrus response, ovulation rate, and pregnancy rate, while it lowered (p < 0.05) the silent estrus incidence when compared to the conventional OVS protocol. In conclusion, the GPGMH protocol, in comparison to the OVS protocol, improves the follicular dynamics, estrus response, ovulation, and pregnancy rates in crossbred multiparous buffaloes during the peak breeding seasons.

Follicular wave emergence and fertility following estrogen based synchronization regimen in anestrus buffaloes (Bubalus bubalis)

The study was undertaken to study the follicular changes around the time of new wave emergence following estradiol-17 (E-17) + controlled internal drug release (CIDR) based synchronization in 30 anestrus buffaloes. The animals were divided in two Groups, viz. Group I and II. In Group I (n=20), on day 0 (beginning of experiment), buffaloes were administered CIDR device (1.38 g P4) and concurrently received 1.5 mg estradiol-17 in 1.5 ml canola oil (i. m.). On day 9, CIDR was removed and a prostaglandin (PG) 2 analogue (500 μg, i. m.) was administered. On day 11, buffaloes were administered gonadotropin releasing hormone (GnRH) analogue (20 μg, i.m.) and inseminated twice at 12 h and 24 h following GnRH injection. Group II (control, n=10) received the CIDR-based protocol except the administration of estradiol at the time of CIDR insert. Ovaries were examined for follicular wave emergence, ovulation of dominant follicles at estrus and subsequent conception at 45 days of insemination. The mean diameter of largest follicle was reduced from 8 mm (0th day) to 4 mm on the day of wave emergence (WE), i.e. day 4 in Group I but day 6 in control. The mean number of 4-5 mm follicle was 5.7 in Group I and 4.8 in control on the days of WE. Ovulation and conception rates achieved were 85 vs 60% and 47 vs 30% respectively. In conclusion the new wave emergence was induced earlier by estradiol-17 administered along with CIDR which ultimately resulted in more ovulation and conception rate in buffalo. Estrogen based protocols might be adopted to improve fertility in anestrum buffaloes.

Presynch-Heatsynch: A New Approach to Improve Ovarian and Fertility Responses in Water Buffalo (Bubalus bubalis)

Background: Standard estrus synchronization regimens resulted in variable outcomes in buffaloes. The present study evaluated ovarian and fertility responses following presynchronization in Heatsynch protocol administered in postpartum buffaloes. Methods: In group-I (Presynch-Heatsynch group, n = 30), PGF2α was administered on days -14 and -2. Then, GnRH analogue, PGF2α (Cloprostenol) and Estradiol benzoate were administered on day 0, 7 and 8, respectively followed by fixed-time artificial insemination (FTAI) 48 hours later. In group-II (Heatsynch group, n = 30), rest protocol was same, except that first two PGF2α injections were not administered. Result: The progesterone concentrations differed (P less than 0.01) between the two groups on days -2, 0 and 7. Post-treatment, progesterone profiles were also higher in pregnant compared to non-pregnant buffaloes in both the groups except on day 10. CL diameter differed (P less than 0.01) between groups on days -2, 0 and 7. It was larger in pregnant than non-pregnant buffaloes on day 7 in both the groups. Dominant follicle diameter remained larger on days -2, 0 and 8 in group-I than -II. Buffaloes getting pregnant had a larger (P less than 0.01) dominant follicle size on the day of FTAI in group-I than of group-II. Ovulatory response of 93.33 and 90.00% was observed in group-I and II. The conception rate was higher (66.66 vs. 40.00%; P less than 0.05) in group-I than Group-II. Presynchronization improved reproductive efficiency in Heatsynch treatment and may aid for better fertility in buffaloes.

110 Pregnancy rate and embryo viability in response to chorionic gonadotrophins given for oestrus induction and gonadotrophin-releasing hormone 5 days after timed laparoscope-aided insemination of lactating and non-lactating goats

Gonadotrophins are included in oestrous/ovulation synchronization (E/OS) regimens when breeding early in the transitional phase to promote follicular development. However, the time of use has been a matter of debate. Hence, the objective of this study was to determine whether equine and human chorionic gonadotrophins (eCG and hCG, respectively) given 24h before or 24h after concurrent removal of intravaginal progestagen (P4) and prostaglandin (PGF2α) delivery influences pregnancy rate (PR) and/or embryo viability (EV). Relatedly, the influence of gonadotrophin-releasing hormone (GnRH) 5 days post-breeding (dpb) on PR and/or EV was also considered. A prospective randomised control trial was conducted using lactating and non-lactating Alpine breed goats of different parity, average±s.e. age, and bodyweight (3.7±2.6), and (52.5±7), respectively. Goats were time-bred at 48h after P4 removal by laparoscopy (LAI; n=75) or by natural service (NS; n=29) during the early transitional breeding phase in mid-September through mid-December (corresponding to 12:12h daylight/darkness). E/OS used an intravaginal device containing 300mg of P4 for 12±1d. At P4 removal, 2mL of PGF2α was administered IM. Twenty-four hours before (E) or 24h after (L) P4 removal, an IM dose of 1.5mL containing 120IU of eCG and 60IU of hCG was given. A third control (C) group (n=38) was not exposed to gonadotrophins. GnRH analogue was given (n=51) 5 days after insemination, and the remaining goats (n=53) received an IM dose of 2mL of saline solution. PR was evaluated at 18 to 24 (dpb) by non-return to oestrus (NRE), at 30 dpb by pregnancy-specific protein B (PSPB), and at 40 dpb by ultrasound imaging (UI). EV was determined from the difference between pregnancy outcomes for NRE and PSPB, and PSPB and UI. Statistical analysis (JMP/SAS vs.11; SAS Institute Inc.) were obtained using logistic regression. All concomitant variables (i.e. parity, bodyweight, days of P4 exposure, and lactation were not influenced by PR or EV; P&amp;gt;0.07). The overall PR was 71% for LAI and 69% for NS and, as shown in Table 1, was similar (P&amp;gt;0.49) at all times (at 18 to 24, 30, and 40 dpb). Likewise, the breeding procedure did not influence the levels of EV at 30 or 40 dpb. E/OS protocol or the use of GnRH 5 dpb did not affect PR or EV at any of the time points evaluated. Table 1. Main effect mean comparisons and logistic model probabilities for pregnancy rate (PR) and embryo viability (EV) by main treatment effect Response variable (days post-breeding) Breeding procedure E/OS Protocol Gonadotrophin LAI NS P&amp;gt; Control Early Late P&amp;gt; GnRH Placebo P&amp;gt; PR at 18–24 77 72 0.49 76 73 78 0.83 78 74 0.49 PR at 30 68 66 0.65 66 65 70 0.82 71 64 0.43 PR at 40 69 69 0.78 66 69 73 0.77 73 66 0.43 EV at 30 89 90 0.94 86 94 90 0.65 92 87 0.46 EV at 40 88 95 0.42 86 89 94 0.73 92 87 0.43

112 Follicular dynamics and oestrus response of Alpine goats with oestrus/ovulation synchronized during the early transitional reproductive phase using gonadotrophin given early or late

Oestrus and ovulation synchronization (E/OS) regimens for fixed-timed breeding are useful when consistently eliciting ovulation. Early synchronization in the reproductive season promotes unreliable oestrus behavioural and physiologic response due to insufficient ovarian priming. In ruminants, equine (eCG) or human chorionic gonadotrophin (hCG) has FSH bioactivity or elicits ovulation, correspondingly. Hence, 120 and 60IU of eCG and hCG, respectively, are included in goat E/OS regimes. This experiment addresses the time when eCG/hCG (CG) is given relative to progestagen (P4) withdrawal and its effect on oestrus and ovulation. Fourteen non-lactating, Alpine breed goats, ranging from 1 to 6 kiddings, averaging±s.d. 3.9±2.0 years of age, and 56.3±5.0kg of bodyweight (BW), and body condition score (BCS) of 2.6±0.2, were evaluated early in the transitional reproductive phase (12h daylight:12h darkness). E/OS was accomplished with 12 day of P4 (200 mg) exposure by intravaginal insert. Three treatments were evaluated: Traditional (T; n=4) did not receive CG and served as the control group; early (E; n=5) received CG 24h before P4 removal; and reverse (R; n=5) received PGF2α 24h before P4 withdrawal as well as CG concurrent with P4 withdrawal. Oestrus response to E/OS was evaluated 24h after breeding using epididymectomized bucks. Ovaries were scanned by transrectal ultrasound (Aloka SSD-500V/7.5-MHz linear array probe) for 4 consecutive days starting with the first i.m. injection of 1.0mL of PGF2α or 1.5mL of CG. Images were digitized (MediCapture™) for later morphometry. The absence of effect (P&amp;gt;0.05) from concomitant variables age, BW, BCS, and parity was ascertained using a logistic regression model (JMP/SAS v15; SAS Institute Inc.). Ovulation, defined as the disappearance of the largest (&amp;gt;7mm) preovulatory follicle on a subsequent observation, was 100, 80, and 100%; and the average±s.e. number of ovulations per goat was 2±0.41, 1±0.32, and 1.3±0.49 (P&amp;gt;0.05). Table 1 summarises follicular size documented of 122 observations of ovulatory areas. Graafian follicle location was not different for left or right ovaries (P&amp;gt;0.05). Oestrus behavioural response to each E/OS treatment (T, E, or L) up to 24h after P4 removal was 50, 80, and 80% (P&amp;gt;0.05), respectively. In summary, oestrus response and ovulation were not affected by the variables studied. In this experience the timing of CG was not relevant. Table 1. Mean diameter (±SE; mm) of nonovulatory and preovulatory follicles on left (L) and right (R) ovaries E/OS protocol Non- and preovulatory Nonovulatory Preovulatory L R L R L R Traditional 6.4±0.6 5.5±0.6 4.8±0.4 4.5±0.4 7.7±0.4 8.9±0.3 Early 5.2±0.3 5.5±0.4 4.9±0.2 4.4±0.3 8.4±1.2 8.1±0.2 Reverse 6.6±0.5 5.3±0.6 5.1±0.4 4.4±0.5 8.7±0.3 8.1±0.2 Overall 5.7±0.19 4.7±0.14 8.3±0.14

Estrous response and pregnancy percentages following use of a progesterone-based, split-time estrous synchronization treatment regimens in beef heifers

Mean estrous response rate (%ERR) and pregnancy/AI percentages (%P/AI) were determined after imposing split-time AI (STAI) and fixed time AI (FTAI) following 14-d controlled internal drug release (CIDR)+PGF2α or 5-d Select Synch + CIDR regimens. In Experiment 1, 1152 heifers (five locations) were randomly assigned to 14- or 5-d and to 54 + 74- or 64 + 84-h STAI treatment combinations. Estrous detection patches were affixed at PGF2α administration (19 day after- and on day 5 at- CIDR removal for 14- and 5-d regimens, respectively), assessed at 54- or 64-h and again at 74- or 84-h after PGF2α. Heifers determined to be in estrus at respective times were inseminated and non-estrous heifers at 74- or 84-h were given GnRH and inseminated concomitantly. The %ERR between 54 + 74- and 64 + 84-h STAI combinations differed (73.2 % and 78.8 %, respectively; P < 0.05), but %P/AI did not. In Experiment 2, 2014 heifers (eight locations) were randomly assigned to 14- or 5-d regimens and were inseminated split-time (64+84-h combination, similar to Experiment 1) or at fixed time (72- or 56-h after PGF2α for 14- or 5-d regimens, respectively). There were differences (P < 0.01) between STAI and FTAI treatments for %ERR (81.3 % and 64.4 %) and %P/AI (61.2 % and 55.4 %). Estrous synchronization regimen by AI treatment interaction (P < 0.05) showed that the %ERR were 79.8 %, 82.6 %, 66.2 % and 62.8 % and the %P/AI were 58.9 %, 63.4 %, 56.5 % and 56.5 % (for 14-d/STAI, 5-d/STAI, 14-d/FTAI and 5-d/FTAI, respectively). In conclusion, the 5-d CIDR with 64+84-h STAI combination was the most effective because of the greater %P/AI when this regimen was imposed.

Superovulation of Boer goats with different synchronization regimens at different times of the year in the northern temperate zone

The present study addresses a comparison of various estrous cycle control protocols and the effect of season in the northern temperate zone on the superovulatory response in Boer goats. Four groups of 12 does each were treated in February, May, August and November, respectively. Does were provided with progestogen containing intravaginal pessaries to synchronize estrus. Half the does of each group received sponges impregnated with 20 mg fluorogestone acetate (“Cronolone”), the other half “Eazy-Breed” CIDRs containing 0.3 mg progesterone. Pessaries remained in place for 7 days. Within each subgroup half the does were treated with PGF2α (“Dinoprost”) at pessary insertion, the other half at pessary withdrawal. Beginning 48 h before pessaries were removed does received i.m. injections of 4, 4, 2, 2, 2 and 2 Armour Units (AU) FSH, supplemented with 40% LH, at 12 h intervals. Estrus detection was conducted at 8 h intervals and ovarian activity was monitored by daily transrectal ultrasonography. Does were mated and 7 days later non-surgical embryo collection was conducted. It transpired that the type of intravaginal pessary had no effect on the time passing between pessary withdrawal and onset of estrus (sponge: 40.7 h vs. CIDR: 35.2 h), number of ovulations/doe assessed by echographic counting of collapsed large follicles (7.2 vs. 7.6) or corpora lutea (7.1 vs. 9.8), embryo recovery rate (39% vs. 41%) and proportion of transferable embryos (66% vs. 65%). The number of collapsed large follicles was significantly higher than that of corpora lutea on the day before embryo collection (7.4 vs. 8.5; P < 0.05), the correlation between the two being r = 0.55 (P < 0.05). The effect of PGF2α administration at the onset or at the end of progestogen treatment and the effect of season were not significant, except for a shorter interval between pessary removal and onset of estrus in August in comparison to the other months (29.3 vs. 39.4, 40.6 and 42.1 h; P < 0.05). In conclusion, Boer goats, although being seasonal breeders in the northern temperate zone, will respond to superovulatory treatment and produce embryos of high quality year round regardless of type of pessary and time of PGF2α administration.

Effects of season and ovarian status on the outcome of long-term progesterone-based estrus synchronization protocols and ovulatory follicle development in Santa Inês ewes under subtropical conditions

This study set out to investigate the efficiency of long-term estrus synchronization protocols and ovulatory follicle dynamics in ultrasonographically monitored Santa Inês ewes during lengthening (LD; September−October) and shortening photoperiods (SD; April−May), and the transitional period (TP; January). In addition, the influence of ovarian status (e.g., size of antral follicles and/or presence of corpora lutea) at the outset of the estrus synchronization protocols on the ensuing development of ovulatory follicles was examined. Seventy sexually mature Santa Inês ewes were subjected to one of the two estrus synchronization regimens; on Day 0 (random day of the estrous cycle or anovulatory period), the ewes were fitted with an intravaginal progesterone (P4)-releasing (controlled intrauterine drug release [CIDR]) device, which was left in place for 14 days (G-1CIDR, n = 35) or replaced on Day 7 (G-2CIDR, n = 35), and received an intramuscular injection of 10 mg of PGF2α. The ewes allocated to the G-1CIDR group had mean serum P4 concentrations less than 2 ng/mL during the last 4 days of the synchronization protocol. There were no differences (P > 0.05) in mean ovulation rates between the two protocols tested nor among the ewes varying in ovarian status or studied at different times of the year, but ovulations occurred ∼12 hours later in the TP compared with the SD period (P < 0.05). Ovulatory follicles emerged earlier (P < 0.05) in the G-1CIDR group than in the G-2CIDR group (Day 8.3 ± 0.5 vs. 9.2 ± 0.4) and during LD (Day 7.1 ± 0.6) compared with the TP (Day 9.1 ± 0.6) and SD (Day 9.9 ± 0.5 of the protocol). In conclusion, the replacement of CIDR devices prevented the occurrence of lower-than-normal luteal phase levels of P4 at the end of the 14-day estrus synchronization protocol. However, although this procedure and seasonal influences altered certain growth characteristics of ovulatory follicles, there were no effects of these factors on the mean ovulation rate.

Fertility response with four estrus synchronization regimens prepubertal buffalo heifers

The use of four estrus synchronization regimens in 43 prepubertal buffalo heifers revealed that progesterone-based hormone regimens (ovsynch+CIDR±eCG) are most favourable for the optimization of their fertility status. Treatment with eCG at CIDR withdrawal had no additional beneficial impact on conception rate. Under field conditions, it may difficult to predict exhibition of induced-estrus/ ovulation in prepubertal heifers, therefore, heifers subjected to Ovsynch+CIDR regimen should be inseminated at 48 (day 9), 72 (day 10) and 96 (day 11) h after CIDR withdrawal.

Fertility Following CIDR Based Synchronization Regimens in Anoestrous Nili‐Ravi Buffaloes

The objective of this study was to compare oestrus expression and fertility rate in used and new controlled internal drug releasing (CIDR) device treated anoestrous buffaloes. Furthermore, to determine the timing of ovulation, and fertility rate in estradiol benzoate (EB) and GnRH-administered CIDR-treated anoestrous Nili-Ravi buffaloes. In experiment 1, buffaloes received either a used CIDR (UCIDR, n = 35) or a new CIDR (NCIDR, n = 36) for 7 day and PGF2α on day 6. Oestrous expression was similar (p > 0.05) between UCIDR (88.5%) and NCIDR (96.6%) buffaloes. The pregnancy rate did not differ (p > 0.05) because of treatment (37.1% in UCIDR vs 36.6% in NCIDR). In experiment 2, buffaloes (n = 55) received CIDR device for 7 days and PGF2α, on day 6 and randomly assigned into three treatment groups: (i) CIDR-EB (n = 17) received EB on day 8, (ii) CIDR-GnRH (n = 18) received GnRH on day 9 and (iii) control (n = 20) received no further treatment. Mean interval from CIDR removal to ovulation in CIDR-EB, CIDR-GnRH and CIDR group were 61.3 ± 0.8, 64.9 ± 1.8 and 65.1 ± 16.7 h, respectively. However, the buffaloes in the CIDR-EB and CIDR-GnRH group had lesser variability in the timing of ovulation compared to control. The pregnancy rate of both CIDR-EB group (58%) and CIDR-GnRH group (61%) were tended to be higher (p < 0.1) than control (30%). In conclusion, compared to NCIDR devices, previously UCIDR devices are equally effective to induce oestrus in anoestrous buffaloes resulting optimal pregnancy rate. Administration of EB and GnRH after CIDR removal results in tighter synchrony (less variability) and improved fertility in anoestrous buffaloes. CIDR based synchronization regimens have great potential in fertility improvement in anoestrous buffaloes.

Evaluation of two oestrus synchronization regimens in eFSH-treated donor mares

Reliable methods for regulating oestrus and superovulation in equine embryo transfer (ET) programs are desirable. The objective in this study was to compare two oestrus synchronization methods combined with equine follicle-stimulating hormone (eFSH) treatment in an ET program. In the progesterone and estradiol-17β (P&E) group, mares (n=12) were given progesterone and estradiol-17β, daily for 10 days, followed by prostaglandin (PG)F(2α) on the last day. In the PG group, mares (n=12) were given PGF(2α) 5 days post-ovulation. In both groups donor mares were allocated to eFSH therapy, and were subsequently bred. Embryo recovery and transfer were performed routinely. The interval to ovulation (mean ± SEM, range) was not statistically different between donor mares in the P&E group (10.2±0.3, 9-12 days) and donor mares in the PG group (8.7±0.7, 4-12 days). Among donor mares, the synchrony of ovulations was higher following the P&E regimen (P<0.05); however, there was a tendency (P<0.06) for fewer ovulations than in the PG group (1.5±0.3 vs. 2.5±0.4 ovulations, respectively). Embryo recovery (0.9±0.3 vs. 1.4±0.3 embryo/recovery) and recipient pregnancy rate per transferred embryo (4/9, 44% vs. 4/15, 27%) were similar. It was concluded that the P&E regimen was more reliable for synchronization of oestrus in eFSH-treated mares but the fewer ovulations may curtail any advantage of this regimen.

Efficiency of superovulation and in vivo embryo production in eFSH-treated donor mares after estrus synchronization with progesterone and estradiol-17β

Reliable methods of regulating estrus and stimulating superovulations in equine embryo transfer programs are desirable. Our objectives were to investigate the efficacy of a progesterone and estradiol-17β (P&E) estrus synchronization regimen in mares with and without subsequent equine follicle-stimulating hormone (eFSH) treatment and to examine the effects of eFSH on folliculogenesis and embryo production. Cycling mares were treated with P&E daily for 10 d. On the final P&E treatment day, prostaglandin F 2α was administered, and mares were randomly assigned to one of two treatment groups (n = 20 mares/group). In both groups, mares were examined daily by transrectal ultrasonography. In the eFSH group, twice-daily eFSH treatments were initiated at follicle diameter 20 to 25 mm and ceased at follicle ≥35 mm; human chorionic gonadotrophin (hCG) was administered after 36 h. In the control group, eFSH treatments were not given, but hCG was administered at follicle ≥35 mm. Mares were inseminated with fresh semen, and embryo recovery attempts were performed 8 d postovulation. Synchrony of ovulations within each group appeared to be similar. Six mares in the eFSH group failed to ovulate. The eFSH treatment resulted in higher (P < 0.05) numbers of preovulatory follicles and ovulations; however, embryo recovery rate did not increase (eFSH 1.0 ± 0.4 vs. control 0.95 ± 0.1 embryos/recovery attempt), and embryo per ovulation rate was significantly lower (36% vs. 73%). The eFSH-treated mares had significantly higher frequency of nonovulatory follicles (28% vs. 0) and higher periovulatory serum concentrations of estradiol-17β. Based on our findings, combined P&E and eFSH regimens cannot be recommended for cycling donor mares.

The effect of addition of equine chorionic gonadotropin to a progesterone-based estrous synchronization protocol in buffaloes ( Bubalus bubalis) under tropical conditions

Poor estrus expression and anestrus decrease the reproductive efficiency of buffaloes. The objective of this study was to determine whether the addition of equine chorionic gonadotropin (eCG) to an estrous synchronization protocol and timed insemination could improve ovulation and pregnancy rates of anestrous buffalo cows under tropical conditions. The study population comprised 65 lactating Murrah buffalo cows which were assigned to CIDR ( n = 33) or CIDR + eCG ( n = 32) treatment groups. Cows in the CIDR group were fitted for 8 d with a controlled intravaginal drug release (CIDR) device containing 1.38 g progesterone, received GnRH (10 μg i.m.) on D 0, PGF 2α (750 μg i.m.) on D 7, and GnRH (10 μg i.m.) on D 9; whereas cows in the CIDR + eCG group received the same treatment plus eCG (500 IU, i.m.) at the time of PGF 2α treatment. All cows were inseminated 16–20 h after the second GnRH treatment. Blood samples were obtained 10 d before the start of synchronization treatment (Day –10) and at the onset of treatment (Day 0). Cows with plasma progesterone concentrations <1 ng/mL recorded in both samples (Low–Low levels of P4) were classified as non-cyclic cows. Similarly, when either one or both of the sample pair contained concentrations of serum progesterone ≥1 ng/mL (High–High, Low–High, or High–Low levels of P4), the buffaloes were classified as cyclic cows. Ovulation rate, defined as the number of buffaloes with at least one corpus luteum 10 days after insemination, was significantly higher ( P = 0.018) in the CIDR + eCG (84.4%) cows than in the CIDR cows (57.6%). Pregnancy rate was numerically lower in CIDR (27.3%) than CIDR + eCG (40.6%) cows, though differences were not significant ( P = 0.25). Pregnancy rates for CIDR + eCG cows were similar to that of cows inseminated after natural estrus (40.9%; 29/71). In the non-cyclic animals, higher ovulation rates ( P = 0.026) were recorded for the CIDR + eCG (81%) than for the CIDR cows (47.4%). Our results indicate that the addition of eCG to a progesterone-based estrous synchronization regimen substantially improves the ovulation rate in non-cyclic buffaloes. When this treatment is followed by timed AI, pregnancy rates achieved in anestrous buffaloes, whether cyclic and non-cyclic, may approach the rates observed in cows inseminated at natural estrus.

155 NOVEL RECIPIENT SYNCHRONIZATION REGIMENS FOR SUCCESSFUL EMBRYO TRANSFER IN THE BRAZILIAN OCELOT FOLLOWING LONG-TERM FROZEN EMBRYO STORAGE

The Brazilian ocelot (Leopardus pardalis mitis) is threatened with extinction in southern Brazil due to habitat loss and poaching. As one component of a bi-national conservation program, efforts have been initiated to establish a Brazilian ocelot population in North American zoos through a combination of natural breeding and assisted reproduction. With improved efficiency, embryo freezing and transfer might be useful as a management tool to help achieve this conservation goal. The objectives of this study were to (1) compare two novel ovarian stimulation regimens for embryo recipient synchronization in ocelots and (2) assess embryo transfer success following long-term (7 yrs) storage of frozen ocelot embryos. Adult female ocelots (n = 8), housed individually at a breeding facility in southern Brazil, were used as recipients. Ovarian activity was monitored noninvasively by assessing fecal estrone metabolite concentrations via a validated enzyme immunoassay. Initial fecal monitoring indicated that all females displayed active ovarian cyclicity. For embryo transfer, fecal samples were collected from each cat and assayed daily over a three week period. Females (n = 4) showing two or more consecutive days of increasing estrone were classified as estrual and treated (Trt 1) with two injections of porcine luteinizing hormone (pLH, 3000 IU dose–1, IM, 13 h interval). Females (n = 4) exhibiting consecutive days of basal estrone levels were considered interestrual and received a combination regimen (Trt 2) of equine chorionic gonadotropin (eCG, 400 IU, IM) followed 85 h later by pLH (3000 IU, IM). Females were anesthetized 50 h after the second hormone injection and evaluated laparoscopically to assess ovarian response. All females exhibited at least one fresh corpus luteum (CL) indicating proper timing of ovulation induction. The number (mean ± SEM) of ovarian follicles (0 v. 3.0 ± 1.5) and CLs (1.0 ± 0.0 v. 3.8 ± 1.8) did not differ (P &gt; 0.05) between treatments. Upon confirmation of ovulation, 3 or 4 frozen embryos (24 embryos total), produced by IVF and frozen in ethylene glycol for liquid nitrogen storage 7 years earlier, were immediately thawed and transferred laparoscopically into one oviduct of each female. At 83 to 84 days post-transfer, two females (one per Trt) each gave birth to one healthy kitten, whereas a third female (Trt 2) experienced dystocia, requiring a C-section to deliver a single healthy offspring. Overall, 38% (3/8) of recipients became pregnant with 33% (3/9) of transferred embryos in pregnant females developing to term. Results indicate that these novel recipient synchronization regimens produce consistent ovulation and a suitable maternal environment for ocelot embryo transfer and that frozen ocelot embryos retain developmental competence after years of storage. Our findings suggest that frozen embryo transfer in ocelots has adequate efficiency for applied usage, allowing international shipment of frozen embryos to be used as a viable alternative to the transport of living ocelots for genetic management (NCRR 015338).

Pregnancy success of lactating Holstein cows after a single administration of a sustained-release formulation of recombinant bovine somatotropin

BackgroundResults regarding the use of bovine somatotropin for enhancing fertility in dairy cattle are variable. Here, the hypothesis was tested that a single injection of a sustained-release preparation of bovine somatotropin (bST) during the preovulatory period would improve pregnancy success of lactating dairy cows at first service.ResultsThe first experiment was conducted in a temperate region of Mexico. Cows inseminated following natural estrus or timed artificial insemination were given a single injection of bST or a placebo injection at insemination (n = 100 cows per group). There was no significant difference between bST and control groups in the proportion of inseminated cows diagnosed pregnant (29 vs 31% pregnant). The second experiment was performed during heat stress in Florida. Cows were subjected to an ovulation synchronization regimen for first insemination. Cows treated with bST received a single injection at 3 days before insemination. Controls received no additional treatment. As expected, bST did not increase vaginal temperature. Treatment with bST did not significantly increase the proportion of inseminated cows diagnosed pregnant although it was numerically greater for the bST group (24.2% vs 17.8%, 124–132 cows per group). There was a tendency (p = 0.10) for a smaller percent of control cows to have high plasma progesterone concentrations (≥ 1 ng/ml) at Day 7 after insemination than for bST-treated cows (72.6 vs 81.1%). When only cows that were successfully synchronized were considered, the magnitude of the absolute difference in the percentage of inseminated cows that were diagnosed pregnant between bST and control cows was reduced (24.8 vs 22.4% pregnant for bST and control).ConclusionResults failed to indicate a beneficial effect of bST treatment on fertility of lactating dairy cows.

Ovarian, hormonal, and reproductive events associated with synchronization of ovulation and timed appointment breeding of Bos indicus-influenced cattle using intravaginal progesterone, gonadotropin-releasing hormone, and prostaglandin F2α1

The objectives of this study were to 1) compare cumulative pregnancy rates in a traditional management (TM) scheme with those using a synchronization of ovulation protocol (CO-Synch + CIDR) for timed AI (TAI) in Bos indicus-influenced cattle; 2) evaluate ovarian and hormonal events associated with CO-Synch + CIDR and CO-Synch without CIDR; and 3) determine estrual and ovulatory distributions in cattle synchronized with Select-Synch + CIDR. The CO-Synch + CIDR regimen included insertion of a controlled internal drug-releasing device (CIDR) and an injection of GnRH (GnRH-1) on d 0, removal of the CIDR and injection of PGF2alpha (PGF) on d 7, and injection of GnRH (GnRH-2) and TAI 48 h later. For Exp. 1, predominantly Brahman x Hereford (F1) and Brangus females (n = 335) were stratified by BCS, parity, and day postpartum (parous females) before random assignment to CO-Synch + CIDR or TM. To maximize the number of observations related to TAI conception rate (n = 266), an additional 96 females in which TM controls were not available for comparison also received CO-Synch + CIDR. Conception rates to TAI averaged 39 +/- 3% and were not affected by location, year, parity, AI sire, or AI technician. Cumulative pregnancy rates were greater (P < 0.05) at 30 and 60 d of the breeding season in CO-Synch + CIDR (74.1 and 95.9%) compared with TM (61.8 and 89.7%). In Exp. 2, postpartum Brahman x Hereford (F1) cows (n = 100) were stratified as in Exp. 1 and divided into 4 replicates of 25. Within each replicate, approximately one-half (12 to 13) received CO-Synch + CIDR, and the other half received CO-Synch only (no CIDR). No differences were observed between treatments, and the data were pooled. Percentages of cows ovulating to GnRH-1, developing a synchronized follicular wave, exhibiting luteal regression to PGF, and ovulating to GnRH-2 were 40 +/- 5, 60 +/- 5, 93 +/- 2, and 72 +/- 4%, respectively. In Exp. 3, primiparous Brahman x Hereford, (F1) heifers (n = 32) and pluriparous cows (n = 18) received the Select Synch + CIDR synchronization regimen (no GnRH-2 or TAI). Mean intervals from CIDR removal to estrus and ovulation, and from estrus to ovulation were 70 +/- 2.9, 99 +/- 2.8, and 29 +/- 2.2 h, respectively. These results indicate that the relatively low TAI conception rate observed with CO-Synch + CIDR in these studies was attributable primarily to failure of 40% of the cattle to develop a synchronized follicular wave after GnRH-1 and also to inappropriate timing of TAI/GnRH-2.

In vivo progestin treatments inhibit nitric oxide and endothelin-1-induced bovine endometrial prostaglandin (PG) E (PGE) secretion in vitro

Synchronization of estrus with progestins in cows has been reported to inhibit nitric oxide (NO) and endothelin-1 (ET-1)-stimulated bovine luteal PGE secretion without affecting prostaglandin F 2α (PGF 2α) secretion in vitro [Weems YS, Randel RD, Tatman S, Lewis A, Neuendorff DA, Weems CW. Does estrous synchronization affect corpus luteum (CL) function? Prostaglandins Other Lipid Mediat 2004;74:45–59]. Two experiments were conducted to determine the effects of NO donors, endothelin-1 (ET-1), and NO synthase (NOS) inhibitors on bovine caruncular endometrial secretion of PGE and PGF 2α in vitro. In Experiment 1, estrus was synchronized in Brahman cows with Synchromate-B ear implants, which contained the synthetic progestin norgestamet. Days 14–15 caruncular endometrial slices were weighed, diced, and incubated in vitro with treatments. Treatments (100 ng/ml) were: Vehicle (control), l-NAME (NOS inhibitor), l-NMMA (NOS inhibitor), DETA (control), DETA-NONOate (NO donor), sodium nitroprusside (NO donor), or ET-1. In Experiment 2, estrus was synchronized in Brahman cows with either Lutalyse (PGF 2α) or a controlled intravaginal drug releasing device (CIDR-containing progesterone) or estrus was not synchronized. Days 14–15 caruncular endometrial slices were weighed, diced, and incubated in vitro with treatments. Treatments (100 ng/ml) were: vehicle, l-NAME, l-NMMA, DETA, DETA-NONOate, sodium nitroprusside, SNAP (NO donor) or ET-1. Tissues were incubated in M-199 for 1 h without treatments and with treatments for 4 and 8 h in both experiments. Media were analyzed for concentrations of PGE and PGF 2α by radioimmunoassay (RIA). Hormone data in Experiments 1 and 2 were analyzed by 2 × 7 and 3 × 2 × 8 factorial design for ANOVA, respectively. Concentrations of PGE and PGF 2α in media increased ( P ≤ 0.05) from 4 to 8 h regardless of treatment group in Experiment 1, but did not differ ( P ≥ 0.05) among treatments. In Experiment 2, concentrations of PGE and PGF 2α increased ( P ≤ 0.05) with time in all treatment groups of all three synchronization regimens. DETA-NONOate, SNAP, and sodium nitroprusside (NO donors) and ET-1 increased caruncular endometrial ( P ≤ 0.05) secretion of PGE 2 in unsynchronized and Lutalyse synchronized cows, but not when estrus was synchronized with a CIDR ( P ≥ 0.05). No treatment increased ( P ≥ 0.05) PGF 2α in any synchronization regimen. It is concluded that norgestamet in Synchromate-B ear implants or progesterone in a CIDR alters NO or ET-1-induced secretion of PGE by bovine caruncular endometrium and could interfere with implantation by altering the PGE:PGF 2α ratio resulting in increased embryonic losses during early pregnancy.

Effects of estrous synchronization on response to nitric oxide donors, nitric oxide synthase inhibitors, and endothelin-1 in vitro

Two experiments were conducted to determine the effects of nitric oxide (NO) donors, endothelin-1 (ET-1), and NO synthase (NOS) inhibitors on bovine luteal function in vitro. In experiment 1, estrus in Brahman cows was synchronized with Synchro-Mate-B (SMB) and day-13–14 corpora luteal slices were weighed, diced and incubated in vitro. Treatments (100 ng/ml) were: vehicle, N ϖ-nitro- l-arginine- l-methyl ester ( l-NAME), N G -monomethyl- l-arginine acetate ( l-NMMA), diethylenetriamine (DETA), DETA-NONOate, sodium nitroprusside (SNP), or ET-1. In experiment 2, estrus was synchronized with Lutalyse, a Controlled Intravaginal Progesterone Releasing Device (CIDR), or cows were not synchronized. Corpora lutea were collected, weighed, and luteal slices were weighed, diced and incubated in vitro with treatments. Treatments (100 ng/ml) were: vehicle, l- NAME, l-NMMA, DETA, DETA-NONOate, sodium nitroprusside, S-nitroso- N-acetylpenicillamine (SNAP) or endothelin-1. Tissues were incubated in M-199 for 1 h without treatments and for 4 and 8 h in both experiments with treatments in both experiments. Media were analyzed for progesterone, prostaglandins E 2 and F 2α (PGE 2, PGF 2α) by radioimmunoassay (RIA). Hormone data in experiments 1 and 2 were analyzed by 2 × 7 and 3 × 2 × 8 factorial design for analysis of variance (ANOVA), respectively. Luteal weights in experiment 2 were analyzed by a one-way ANOVA. Concentrations of progesterone in media were similar ( P ≥ 0.05) among treatments within experiments. Concentrations of PGE 2 in media in experiment 1 were undetectable in 90 and 57% of the samples at 4 and 8 h, respectively. PGF 2α increased ( P ≤ 0.05) with time, but did not differ ( P ≥ 0.05) among treatments. Secretion of PGF 2α was not affected by treatments ( P ≥ 0.05). In experiment 2, luteal weights of the induced estrous cycle were decreased ( P ≤ 0.05) by Lutalyse. Concentrations of PGE 2 and PGF 2α increased ( P ≤ 0.05) with time in control of all three synchronization regimens. DETA-NONOate, SNAP, sodium nitroprusside (NO donors) and ET-1 increased ( P ≤ 0.05) PGE 2 except in the CIDR synchronized group ( P ≥ 0.05). No treatment increased ( P ≥ 0.05) PGF 2α in any synchronization regimen. It is concluded that either SMB containing norgestomet or a CIDR containing progesterone alters luteal secretion of PGE 2, Lutalyse lowers luteal weights in the induced estrous cycle, and NO or ET-1 given alone are not luteolytic agents. It is suggested that NO and ET-1 could have indirect antiluteolytic/luteotropic effects via increasing PGE 2 secretion by luteal tissue rather than being luteolytic.