Estrous Synchronization Treatment Research Articles

Plasma progesterone profiles in ewes using different injectable progesterone formulations

Context The use of progesterone vaginal implants in sheep is frequently associated with vaginitis and adherences; and can hamper fertility in estrus synchronization programs. Aims The aim of this study was to characterize the plasma hormone profile induced by two injectable progesterone (iP4) formulations in ewes. Methods In Experiment 1, ewes received 20 or 40 mg of an iP4, with a third group as a control. In Experiment 2, 75 or 150 mg of a long-acting iP4 were administered, again with a control group. Key results In Experiment 1, progesterone concentrations remained at luteal levels for less than 24 h. The intervals from iP4 treatment to the onset of estrus and ovulation were greater in treated than in control ewes (P < 0.01). The proportion of ewes that ovulated within 8 days after treatment was lower in ewes that received 40 mg iP4 than in control ewes (P < 0.05). In Experiment 2, mean progesterone concentrations remained at luteal levels for 120 h. The interval from iP4 administration to estrus was longer in 150 mg treated ewes than in control ewes (P < 0.01). The interval from treatment to ovulation was longer in ewes treated with 150 mg than 75 mg and control ewes (P < 0.05). The proportion of ewes that ovulated was lower at 150 mg (P < 0.05). Conclusions The iP4 formula used in Experiment 1 could not maintain luteal levels for more than 24 h. The use of long-acting iP4 maintained plasma progesterone concentrations above luteal levels for at least 5 days. The long-acting treatment can therefore be tested for estrous synchronization treatments. Implications The long-acting progesterone may be an alternative to short estrous synchronization protocols.

Influence of hormonal treatments on progesterone levels to enhance embryo survival and kidding rates in goats.

This study investigated the efficiency of different estrous synchronization programs and hormonal treatments in improving reproductive outcomes in goats. Conducted on a commercial farm in southern Thailand, the study used multiparous Shami and Anglo-Nubian breed goats. In experiment 1, goats were randomly allocated to two estrous synchronization treatments: 11-day (CI11D) and 13-day (CI13D) intravaginal progesterone implants, followed by artificial insemination (AI) with frozen-thawed semen. Various hormonal treatments (human chorionic gonadotropin (hCG), GnRH analogue, progestogen) were administered on day 5 post-AI to elevate progesterone levels. Experiment 2 assessed embryo survival after transferring early- and late-stage embryos, using GnRH analogue to increase progesterone levels in the recipient goats. Results showed that GnRH analogue significantly increased pregnancy rates, kidding rates, and the number of kids born in the CI13D group. Progesterone levels were higher in treated groups, particularly with GnRH analogue, though estradiol levels varied between synchronization protocols. Late-stage embryo transfers significantly improved pregnancy rates and reduced embryonic loss compared to early-stage transfers. GnRH analogue supplementation reduced early embryonic mortality, enhancing embryo survival and overall reproductive performance. This study demonstrates the efficacy of tailored estrous synchronization and hormonal treatments in optimizing goat reproductive outcomes, with significant implications for improving fertility management in commercial goat farming. Although no significant differences were observed in progesterone levels, the administration of GnRH analogue reduced early embryonic mortality and improved reproductive outcomes, demonstrating its potential to enhance embryo survival and reproductive performance in goats.

Refinements in embryo manipulation applied to CRISPR technology in livestock

The implementation of CRISPR technology in large animals requires further improvements in embryo manipulation and transfer to be applied with commercial purposes. In this study we report (a) developmental competence of CRISPR/Cas microinjected zygotes subjected to in vitro culture in large scale programs in sheep; (b) pregnancy outcomes after early-stage (2–8-cell) embryo transfer into the oviduct or the uterine horn; and (c) embryo survival and birth rate after vitrification/warming of CRISPR/Cas microinjected zygotes. Experiment 1 consisted of a retrospective analysis to evaluate embryo developmental rate of in vitro produced zygotes subjected to CRISPR/Cas microinjection (n = 7,819) compared with a subset of non-microinjected zygotes (n = 701). Development rates to blastocyst on Day 6 were 20.0% for microinjected zygotes and 44.9% for non-injected zygotes (P < 0.05). In Experiment 2, CRISPR/Cas microinjected zygotes were transferred on Day 2 after in vitro fertilization (2-8 cell embryos) into the oviductal ampulla (n = 262) or into the uterine horn (n = 276) in synchronized recipient ewes at prefixed time (i.e., approximately two days after ovulation). Pregnant/transferred recipients (24.0% vs. 25.0%), embryo survival/transferred embryos (6.9% vs. 6.2%), and born lambs/pregnant embryos (72.2% vs. 100.0%) did not differ significantly in the two groups. In Experiment 3, CRISPR/Cas microinjected zygotes were maintained under in vitro culture until blastocyst stage (Day 6), and subjected to vitrification/warming via the Cryotop method (n = 474), while a subset of embryos were left fresh as control group (n = 75). Embryos were transferred into the uterine horn of recipient females at prefixed time 8.5 days after the estrous synchronization treatment (i.e., approximately six days after ovulation). Pregnancy rate (30.8% vs. 48.0%), embryo survival rate (14.8% vs. 21.3%), and birth rate (85.7% vs. 75.0%) were not different (PNS) between vitrified and fresh embryos, respectively. In conclusion, the current study in sheep embryos reports (a) suitable developmental rate after CRISPR/Cas microinjection (i.e., 20%), even though it was lower than non-microinjected zygotes; (b) similar outcomes when Day 2-embryos were placed into the uterine horn instead of the oviduct, avoiding both time-consuming and invasive oviduct manipulation, and extended in vitro culture during one week; (c) promising pregnancy and birth rates obtained with vitrification of CRISPR/Cas microinjected embryos. This knowledge on in vitro embryo development, timing of embryo transfer, and cryopreservation of CRISPR/Cas microinjected zygotes have practical implications for the implementation of genome editing technology in large animals.

Ovarian and Energy Status in Lame Dairy Cows at Puerperium and Their Responsiveness in Protocols for the Synchronization of Ovulation.

The purpose of this study was to assess the ovarian and energy status of multiparous lame dairy cows at the end of puerperium and investigate their responsiveness to estrous synchronization treatment regimens. Initial lameness scoring was performed at 28 ± 5 and 37 ± 5 d post partum, followed by lesion documentation and treatment. Cows were blocked by lameness severity and were randomly allocated to an estrous synchronization treatment regimen with seven days of progesterone supplementation (group LP, n = 26) or with an administration of PGF2α twice, 14 d apart (group LC, n = 26). Non-lame cows served as controls (group C, n = 27) and the same treatment regimen was imposed as that for group LC. Twelve days after estrous presynchronization, an Ovsynch treatment regimen and timed AI were imposed. Ultrasonography of the ovaries and blood sampling for progesterone were used to assess cyclicity status, whereas β-hydroxybutyrate (BHBA) and non-esterified fatty acids (NEFA) were used to assess energy status. Lame cows were to a greater proportion non-cycling (36.5% vs. 11.1%; p = 0.02), had greater overall NEFA concentrations (0.32 ± 0.02 vs. 0.26 ± 0.02 mEq/L; p = 0.02) and a greater incidence of elevated NEFA concentrations (53.9% vs. 29.6%, p = 0.04) compared to control cows. However, no interaction between energy and lameness status was evident regarding non-cycling cows. The percentage of cows responding to the presynchronization, synchronization and ovulating did not differ between groups LP, LC, and C. The first-service conception rate (FSCR) tended to be greater for group C (37.0%) compared to group LP (16.0%; p = 0.08). Long-term reproductive performance did not differ between lame and control cows, although culling rates did (21.2% vs. 0%, respectivly; p = 0.01). The severity of lameness had an effect on culling rates (30.6% vs. 0% for cows with marked vs. moderate lameness; p = 0.01), whereas the type of lesion largely explained poor reproductive performance (FSCR 13.9% vs. 40.0% for cows with claw horn disruptions vs. infectious lesions; p = 0.04). Conclusively, cows that were lame during puerperium are at a greater risk of not cycling irrespective of energy status. Treatment regimens for the synchronization of ovulation seem to be efficient at resuming ovarian cyclicity. Marked lameness was detrimental to survivability, whereas cows with claw horn lesions had compromised reproductive capacity.

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%).

Puberty attainment and reproductive performance of yearling Bos indicus-influenced heifers after two sequential treatments with progesterone

Number of pubertal heifers at time of breeding season initiation is a primary determinant to pregnancy success during the breeding season. It was hypothesized that pre-breeding progesterone (P4) supplementation (induction) would increase the number of heifers pubertal at the time of imposing estrous synchronization treatment regimens and P/AI. Yearling, Bos indicus-influenced (n = 577) or Bos indicus (n = 174) heifers were or were not treated with P4 (CIDR and Non-CIDR, respectively) for 10 d starting on D-23 (D0 = TAI). Presence of a CL on D-33 or D-23 was considered to indicate heifers were pubertal. On D-13, there was a PGF analogue administered. On D-9, there was treatment with GnRH analogue, 6d-CIDR and PGF. There were inseminations based on estrus (D-2 to D0) or TAI on D0 for non-estrous animals. There were 5.2 % and 62.9 % purebred and crossbred heifers pubertal, respectively. Proportion of prepubertal crossbred than purebred heifers with CL on D-3 was greater as a result of imposing the pubertal induction regimen (P < 0.05 and P> 0.10, respectively). Regardless of puberty status, proportion of heifers in estrus prior to AI in the CIDR group was similar to the heifers of the Non-CIDR group for crossbreds and purebreds. Similarly, P/AI of CIDR group was similar to the Non-CIDR group for crossbreds and purebreds. In summary, imposing the pubertal induction regimen hastened attainment of puberty in yearling crossbred, but not purebred heifers. Puberty induction did not affect estrous response, neither fertility after imposing an estrous synchronization treatment regimen.

Lack of effect of melatonin on ovarian function and response to estrous synchronization and fixed-time AI during the nonbreeding season in lactating dairy buffalo (Bubalus bubalis)

The present study was conducted to examine whether pretreatment with melatonin would enhance ovarian follicular functions and increase response to estrous synchronization and fixed-time AI (TAI) during the nonbreeding season in lactating dairy buffalo. In Experiment 1, buffalo cows without a detectable corpus luteum (CL) were assigned on Day -20 (D-20) to three groups: control (n = 12); melatonin (n = 13); progesterone (P4) (n = 15). Cows in the melatonin group were implanted with melatonin on D-20. From D0 to D9, there was imposing of an estrous synchronization treatment regimen using either a standard Ovsynch protocol (control, melatonin) or a P4-based Ovsynch treatment regimen (P4). There were no differences (P > 0.05) among groups for the presence of a CL at D0, size of the largest follicle at D0, ovulation to GnRH injection at D0 and D9, or the time to ovulation after injection of GnRH at D9. In Experiment 2, there was imposing of the same treatment regimens as in Experiment 1, with inclusion of TAI. Females of the P4 group had a greater (P = 0.001) pregnancy/AI percentage (60 %) than those in the control (17 %) and melatonin (23 %) groups. Females of the P4 group also had a larger (P = 0.005) CL at D20 compared with those in the control and melatonin groups. Findings indicate treatment with melatonin for 20 days did not affect ovarian functions or the response to an estrous synchronization treatment regimen and TAI during the nonbreeding season in lactating dairy buffalo.

The Use of hCG for Inducing Ovulation in Sheep Estrus Synchronization Impairs Ovulatory Follicle Growth and Fertility.

Simple SummaryThe present study, in view of the importance of finding an alternative hormone to eCG, aims to determine the response of sheep to hCG-based treatments. The findings indicate that the low fertility rates reported for protocols based on the administration of hCG for inducing ovulation during estrus synchronization in sheep may be related to a high occurrence of abnormal follicular growth patterns, disturbances, and retardments of ovulation and concomitant formation of follicular cysts in the treated females. These results preclude their practical application to induce ovulation concomitantly to estrous synchronization treatments.Currently, there is an intense effort to find an alternative hormone to eCG to induce ovulation after estrus synchronization treatments in sheep. One of the proposed alternatives is based on the use of hCG, but the results are controversial since fertility rates are commonly affected. The present study aims to evaluate, therefore, the adequacy of hCG in protocols for the synchronization of estrus and ovulation. Ovarian follicle dynamics, occurrence of estrus behavior and subsequent ovulation, quality of corpora lutea, and pregnancy rate after controlled natural mating were assessed in two consecutive trials. The findings indicate that the low fertility rates reported for the protocols based on the administration of hCG for inducing ovulation during estrus synchronization in sheep may be related to a high occurrence of abnormal follicular growth patterns, disturbances, and retardments of ovulation and concomitant formation of follicular cysts in the treated females. These results preclude their practical application to induce ovulation concomitantly to estrous synchronization treatments.

Estrous Performance of Etawah Crossbred Goats Following Different Estrous Synchronization Methods

The objective of the research was to determine the estrous profile of Etawah Crossbred goats after estrous synchronization with different methods. Eighteen does aged 12-24 month old were divided in three groups to receive estrous synchronization treatments (T1 = 14 days intravaginal implant of 60 mg of progesterone (MPA), T2 = two times injection of 5 mg PGF2α (lutalyse) in 11 days interval, and T3 = 10 days of intravaginal implant of 60 mg of progesterone (MPA) + injection of 5 mg PGF2α 48 hours before removal) with six replications. The parameters consisted of estrous behaviour, changes in size and colour of vulva, and duration of estrus when the number of superficial and keratin cells were dominating in the vaginal mucus cell. Data from estrous behaviour and score of vulvar colour was analyzed using Kurkal Wallis test, while onset of estrus, size of vulva slit and estrous duration was analyzed using ANOVA and Duncan test. The result showed that estrous behaviour and changes in color and size of vulva were not significantly different, but estrous duration was significantly different. Estrous duration in T1 (31.30 hour) and T2 (31.10 hour) was significantly longer than that of T3 (11.36 hour). It is concluded that different methods of estrus synchronization affected estrous quality equally but it affected the estrous duration differently based on vaginal mucus cells. Treatment implant vaginal sponge content progesterone for 14 days and double injection of PGF2α with 11-day interval given longest estrous duration.

Timed artificial insemination strategies with or without short-term natural service and pregnancy success in beef heifers

Objective was to compare estrous response, and first service and breeding season pregnancy rates in Angus cross beef heifers that received four progesterone (CIDR, vaginal insert) -based estrous-synchronization treatment regimens for timed artificial insemination (TAI) with or without short-term natural service (NS). Heifers (n = 1744; 4 locations) were assigned a reproductive tract score (RTS: 1 = immature, acyclic to 5 = mature, cyclic), body condition score (BCS: 1 = emaciated to 9 = obese) and temperament score (0 = calm to 1 = excitable). Within location, heifers were assigned to either of four treatment regimens. Heifers in Select-Synch + CIDR (C) + short-term NS (SSC + NS) treatment (n = 438) received 100 μg GnRH im + CIDR on Day −7 and CIDR removal + 25 mg PGF2α (im) + estrus-detection patches in the morning of Day 0 and were subjected to NS (bull to heifer ratio, 1:25) from the morning of Day 2 (48 h from CIDR removal) to evening of Day 8. Heifers in CO-Synch + C (COSC) +TAI + NS treatment (n = 433) received 100 μg GnRH + CIDR on Day −7 and CIDR removal + 25 mg PGF2α im + estrus-detection patches in the morning of Day 0 + 100 μg GnRH im + TAI on Day 2, 60 h from CIDR removal, and were subjected to natural service (bull: heifer, 1:25) from the evening of Day 2 immediately after AI through Day 8. Heifers in COSC + TAI treatment (n = 443) received 100 μg GnRH + CIDR on Day −7 and CIDR removal + 25 mg PGF2α im + estrus-detection patches in the morning of Day 0 + 100 μg GnRH im + TAI on Day 2, 60 h from CIDR removal. Heifers in SSC + split time AI (STAI) treatment (n = 430) received 100 μg GnRH + CIDR on Day −7 and CIDR removal + 25 mg PGF2α im + estrus-detection patches in the morning of Day 0. Heifers determined to be in estrus were inseminated at 64 h after PGF2α (25 mg, im) administration and non-estrous heifers determined to be in estrus 20 h later (at 84 h) were inseminated at that time, whereas remaining non-estrous heifers at 84 h received GnRH (100 μg) and were inseminated concomitantly. In SSC + NS and COSC + TAI + NS treatments, natural service bulls were removed and reintroduced (@ bull: heifer, 1:40) on Day 22 and kept until Day 63. In COSC + TAI and SSC + STAI bulls (bull: heifer, 1:40) were introduced on Day 14 and retained until Day 63. All heifers, irrespective of treatment regimens, were observed for estrus three times a day from Day 2 through Day 8. Pregnancy diagnosis was performed on Day 93, 30 days from end of breeding season. Accounting for temperament (P < 0.0001), BCS (P < 0.0001) and RTS (P < 0.0001), the breeding program influenced the estrous response (P < 0.0001). Heifers in COSC + TAI + NS (86.8%), SSC + STAI (84.9%), and SSC + NS (86.5%) treatments had greater estrous response compared with heifers in COSC + TAI (75.8%) treatment. Accounting for temperament (P < 0.01), BCS (P < 0.05) and RTS (P < 0.01), the treatment regimens influenced first service pregnancy rate (P < 0.05). Heifers in COSC + TAI + NS treatment had greater first service pregnancy rate (60.3%) compared with COSC + TAI (54.2%) (P < 0.05). First service pregnancy rate for heifers in SSC + STAI (59.3%) and SSC + NS (57.3%) treatments did not differ from COSC + TAI + NS and COSC + TAI treatments. Accounting for temperament (P < 0.001), BCS (P < 0.0001) and RTS (P < 0.0001), the treatment regimens influenced breeding season pregnancy rate (P < 0.05). Breeding season pregnancy rate for heifers in COSC + TAI + NS (95.4%) and COSC + STAI (94.5%) treatments were greater than that of heifers in COSC + TAI (90.8%) treatment (P < 0.05), and heifers in SSC + NS (94.1%%) treatment did not differ from heifers in other treatments. In conclusion, progesterone-based CO-Synch timed artificial insemination with short-term natural service treatment regimen resulted in proportionately more pregnancies than without short-term natural service treatment regimen. In addition, 64/84 h split-time AI or natural service following Select-Synch treatment regimen could be implemented as an alternative as these treatment regimens resulted in similar pregnancy rate as progesterone based CO-Synch timed artificial insemination with short-term natural service treatment regimen.

Short- and long-term effects of temporary early cow–calf separation or restricted suckling on well-being and performance in zebu cattle

Information on weaning techniques in the tropics is scarce, particularly regarding the long-term effect of temporary early cow–calf separation or restricted suckling. Therefore, we studied the effects of these two handling practices on well-being and performance at 150 days postpartum in fifteen zebu cow–calf pairs randomly assigned to three treatments. Continuous suckling (CS) where calves remained with their dams from birth to weaning; restricted suckling (RS) calves were allowed to suckle 30 min/day from Day 34 until weaning at Day 150 and kept separated the rest of the time; temporary separation (TS) calves were separated for 72 h from their dams from Day 33 to 36 but remained with their dams the rest of the time. Blood samples and behavioral data were collected on Days 32–36 (1st period) and 149–153 (2nd period). In the 1st period, a greater percentage of RS and TS calves were observed close to the fence line (<10 m) that separated them from their dams (P < 0.0001) and vocalized more than CS calves (P < 0.0001), while in the 2nd period, RS calves had the highest cortisol concentration and vocalization rate (P < 0.05). Similarly, during the 1st period, a greater percentage of RS and TS cows were observed close to the fence line than CS cows (P < 0.0001), with TS cows vocalizing the most (P = 0.001). In the 2nd period, RS cows had greater cortisol concentration than TS (P = 0.037) and CS cows (P = 0.003). More TS and CS cows than RS were observed close to the fence line (P = 0.03 and P = 0.05). On Day 150, TS calves and cows vocalized more than RS and CS animals (P < 0.0001). Before calf–cow separation, 27 out of 45 cows were cycling (CS = 10; RS = 6; TS = 11). After separation, 12 of the remaining 18 cows resumed ovarian activity (CS = 3; RS = 5; TS = 4), and all cows were cycling after estrous synchronization treatment. The pregnancy rate was similar between CS, RS, and TS (60, 53, and 60% respectively). In conclusion, temporary separation increased calf distress response to definitive weaning even four months later, while restricted suckling seemed to reduce it.

The Effect of PRID on the hemodynamics of preovulatory follicular, luteal and the ovarian arteries in Egyptian buffaloes

The aim of the present investigation was to study the comparative efficacy of two estrous synchronization treatments on follicular, luteal changes, and ovarian hemodynamic associated with hormonal changes of progesterone and estrogen in addition to nitric oxide. Six cyclic buffalo cows were scanned daily along three successive estrous cycles transrectal by Doppler ultrasonography to evaluate the normal ovarian hemodynamic during normal spontaneous ovulation and before the start of experiments. Buffaloes in the current study will be categorized according to the experimental design. The buffalo cows in the first experiment were synchronized with progesterone releasing intra-vaginal device (PRID) - PGF2α (7 days inserted PRID and PGF2α injected on the 6th day, n = 6). In experiment 2 the same animals (n = 6)) were taken a rest for two successive estrous cycles. Then, buffaloes were synchronized with PRID- Modified Co- synch (PRID+GnRH) in which, 7 days inserted PRID intra-virginal then animals will receive 10μg of GnRH at day 0, 250μg of PGF2α at day 7, another 10μg of GnRH administered 48h after the PGF2α injection. Blood sampling and ovarian ultrasound examinations (color and power Doppler modes) were conducted on the day of PRID removal, estrous, and luteal phase. Results revealed that buffaloes treated with PRID - PGF2α had a higher total number of follicles and F1 dominant diameter. Color Doppler ultrasonography revealed that, F1 diameter, F1 area/pixel, F1 antrum area/pixel, F1 granulosa area, and F1 colored area/pixels significantly increased in PRID -PGF2α group as compared to normal spontaneous ovulating and PRID+GnRH group. In addition, the CL diameter and their vascularity (CL Area/pixels, CL Color area/pixels, CL Color area %) were markedly increased in PRID -PGF2α group as compared to normal spontaneous ovulating and PRID+GnRH group concurrent with a high level of plasma estrogen. The higher values of resistance index (RI) of ipsilateral and contralateral ovarian arteries were recorded in PRID -PGF2α and PRID+GnRH compared to the normal spontaneous ovulating. A similar tendency was observed in blood flow volume (BFV). However, the ovarian blood flow indices including time average mean velocity (TAMV) and peak systolic velocity PSV) did not change among different groups. A higher level of plasma estrogen was achieved in PRID -PGF2α as compared to other groups. However, the progesterone levels did not vary among groups. The nitric oxide level was significantly higher in PRID+GnRH as compared to others. In conclusion, synchronization with the PRID -PGF2α protocol could be enhanced the follicular activity and hemodynamics of Egyptian buffaloes.

Size and number of corpora lutea and serum progesterone concentrations when administering two doses of eCG in an estrous synchronization treatment regimen for dairy cattle

There was investigation of whether there were ovulations from co-dominant follicles following eCG administration. In all experiments, there was GnRH injection and CIDR insertion on day 0 (D0), CIDR withdrawal on D8, and cloprostenol administration on D8 (Exp. I and II) or D7 and D8 (Exp. III). Females in the control group were not administered any further treatment. Females in other group(s) were treated with eCG (500 IU) on Day 2 in Exp. I, Day 2 (eCG-2) or 8 (eCG-8) in Exp. II and Day 2 (eCG-2) or Days 2 and 6 (eCG-2-6) in Exp. III. Ovaries were examined using ultrasonography. In Experiments I and II, females had follicle emergence on Day 2. At the time of CIDR removal, more eCG-treated heifers (8/9; Exp. I) and cows (5/6; eCG-2; Exp. II) had co-dominant follicles compared to those in the control group (P < 0.05). Occurrence of ovulations from co-dominant for individual cows was minimal. In Experiment III, the time period from CIDR removal to estrus in cows treated with eCG-2 (68 ± 13 h) was longer compared to cows in the control (37±2 h) and eCG-2-6-treated group (38 ± 5 h; P < 0.05). There was a greater proportion of heifers having ovulations and thus greater progesterone concentration in the eCG-2-6 than eCG-2 group (P < 0.05). Administering eCG twice 4 days apart with the initial administration being two days after GnRH administration, at the time of follicle wave emergence, could induce growth of and ovulation from co-dominant follicles and enhance progesterone production in cattle.

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.

Identification and characterization of putative ovarian lincRNAs in dairy goats treated for repeated estrous synchronization

The goal of this study was to identify and characterize effects of repeated estrous synchronization (ES) treatments on the regulation of ovarian intergenic long non-coding RNAs (lincRNAs) in dairy goats. Six does were randomly assigned to a group administered three ES treatment regimens separated by 2 weeks or to a group administered only one ES treatment regimen (control) at the same time as the third ES treatment in the does administered the three hormonal regimens for ES. The paired-end RNA Sequencing procedures were used to evaluate lincRNAs of ovarian tissues. A total of 134 lincRNAs were differentially abundant between the two treatment groups. Several target genes were annotated and were related to hormone activity, cellular response to hormone stimulus, response to hormone, female pregnancy, as well as regulation of hormone secretion. These genes were noticeably enriched in MAPK, Hippo, estrogen signaling pathways, oocyte meiosis, progesterone-mediated oocyte maturation, ovarian steroidogenesis as well as GnRH signaling pathways. According to the enriched GO terms and KEGG pathways of regulated genes, 13 differentially abundant lincRNAs could be promising candidates for regulating reproductive functions of female goats. Current results indicate that repeated treatments with gonadotropins affected hormone sensitivity, estrogen synthesis, and ovarian function. The results also indicated that when there was imposing of the three hormonal treatment regimens for ES, there were several lincRNAs that could contribute to dysregulation of several genes that are important for reproduction in dairy goats. Findings provide novel insights for further investigation of lncRNAs biological functions in goats.

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

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

Decreasing the dose of equine chorionic gonadotropin does not affect ovarian or pregnancy responses of purebred taurine and crossbred beef heifers

In this study there was evaluation of effects of different doses of equine chorionic gonadotropin (eCG: 200, 300, or 400 IU) administrated at progesterone (P4) plus estradiol-based timed AI (TAI). A total of 1080 heifers were included in the study. There was insertion of the intravaginal P4-device plus administration of 2 mg of estradiol benzoate IM. On D7, 12.5 mg of dinoprost tromethamine IM was administered and on D9, the P4 insert was removed and 0.5 mg of estradiol cypionate IM was administered. Heifers were categorized according to Reproductive Tract Status (RTS; 1−5) and were assigned to one of three treatments: 200 IU (n = 387), 300 IU (n = 357), or 400 IU (n = 336) of eCG. Estrous occurrence was evaluated at TAI 48 h later (D11). A subset of heifers (n = 213) had the largest follicle (LF) evaluated on D9 and on D11, and the formation of a new CL evaluated on D18.There was no effect of eCG treatment on LF on D11 (P = 0.79), occurrence of estrus (P = 0.92), and pregnancy at 30 days after AI (P/AI; 52.2%, 49.8%, and 51.5% for 200 IU, 300 IU, and 400 IU, respectively; P = 0.46). Regardless of the treatment, there was a greater P/AI when heifers had a functional CL, at initiation of the estrous synchronization treatment regimen. It, therefore, is efficacious to reduce the dose of eCG to 300 or 200 IU in purebred taurine and crossbred beef heifers without negative effects on ovarian, estrous or pregnancy responses.

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.

Effects of estrous expression and intensity of behavioral estrous symptoms on variables associated with fertility in beef cows treated for fixed-time artificial insemination

This experiment was conducted to evaluate effects of estrous expression and intensity of behavioral estrous expression, assessed by evaluating physical activity, on variables associated with fertility in beef cows. The following treatment regimen was imposed on lactating, multiparous cows (n = 273): 100-μg injection of GnRH and an intravaginal progesterone (P4) releasing device (CIDR) administered on d -10, 25-mg injection of prostaglandin F2α at CIDR removal on d -3, and another GnRH injection + fixed-time artificial insemination (TAI) 60−66 h following CIDR removal (d 0). Cows were fitted with a pedometer on d -10, and an estrous detection patch on the tail-head on d -3. Cows were classified as not expressing estrus (NOESTR) or expressing estrus with net physical activity greater (HIESTR) or less than the median (LWESTR). Only data from cows responsive to the estrous synchronization treatment regimen were utilized (NOESTR, n = 119; LWESTR, n = 50; HIESTR, n = 50). Diameter of dominant follicles on d 0 and corpus luteum volume on d 7 were greater in HIESTR compared with LWESTR and NOESTR groups (P < 0.01). Plasma P4 concentrations on d 7 and pregnancy rates to TAI were greater in HIESTR and LWESTR than the NOESTR group (P < 0.01). Hence, if there was estrous expression during the period of the GnRH-based TAI treatment regimen, there were greater pregnancy rates to TAI, whereas when there was greater intensity of behavioral estrous symptoms, there were larger dominant follicles and corpora lutea dimensions but not greater pregnancy rates.

Effects of Polyunsaturated Fatty Acids (PUFA) Supplementation on Reproductive Performance of Beef Heifers Submitted to Fixed-time Artificial Insemination (FTAI) Protocol

Background: More recently, polyunsaturated fatty acids (PUFA) supplements have been used in grazing beef herds in attempt to influence specific metabolic pathways and hormones that directly modulate reproductive function. Supplementation of calcium salts of PUFA can positively influence ovarian follicular growth, luteal function, and improve reproductive performance in dairy and beef females. The aim of this experiment was to evaluate strategies of dietary treatments using PUFA supplementation for 30 days before or after FTAI protocol and its effects on of ovulatory follicle size, ovulation, pregnancy and gestational losses rates in beef heifers.Materials, Methods &amp; Results: One hundred and ninety-nine Brangus heifers (24 ± 3 months-old; BW= 320 ± 15 kg; BCS= 2.85 ± 0.17) were randomly assigned in three different groups to receive dietary treatments. Group 1 (n = 70) was fed with 0.5 kg/day of a protein-mineral mixture supplement containing 0.2 kg/day PUFA (Mix A)during 30 days before FTAI, Group 2 (n = 68) received the same supplement 30 days after FTAI and Control (n = 61) only the supplement without PUFA (Mix B) during all period. Heifers were submitted to estrous synchronization treatment using progesterone (P4), estradiol benzoate (E2) and prostaglandin F2a (PGF). Ultrasound exams were done to measure ovulatory follicle diameter and to determinate ovulation and pregnancy rates on Day 30 and 60 after FTAI. Daily gain (DG) was higher (P &lt; 0.05) only when heifers received supplement containing PUFA (Group 1= 30 days prior FTAI) and (Group 2= 30 days after FTAI). PUFA supplementation before FTAI also resulted in larger ovulatory follicles diameter (P &lt; 0.05) in Group 1 (11.2 ± 2.5 mm) compared to Group 2 (9.9 ± 2.3 mm) and Control (10.0 ± 2.07 mm). Ovulation rates were similar (P &gt; 0.05) in Group 1 (90%), Group 2 (75%) and Control (67%). Pregnancy rates were higher (P &lt; 0.05) in Group 1 (Day 30= 67.1% and Day 60= 64.2%) when compared with Group 2 (Day 30= 48.5% and Day 60= 44.1%) and Control (Day 30= 49.2% and Day 60= 45.9%). Gestation losses were similar (P &gt; 0.05) among Groups 1 (6.6%), 2 (9%) and Control (6.6%).Discussion: Rumen-protected supplemental lipids have been used to increase energy density and to determine direct positive effects on reproduction in dairy and beef herds. There is evidence that feeding moderate amounts of PUFA supplements can improve energy status and result in significant differences in DG as it was observed during experimental period. Thus, heifers that received 0.2 kg/day of PUFA supplement 30 days before FTAI protocol had also a positive effect on ovulatory follicles size, but ovulation rates were similar in groups. Beneficial effects of pre-breeding PUFA supplementation were observed on pregnancy rates on Days 30 and 60 after FTAI, but pregnancy loss was not different among dietary treatments in beef heifers. Based on this study, PUFA supplementation before FTAI protocol had a positive effect on reproductive performance of beef heifers by directly improving ovarian function, uterine environment and early embryonic development. Results indicate that pre-breeding PUFA supplementation to beef heifers is a suitable strategy to increase pregnancy rate in FTAI programs. Therefore, for a better understanding of interactions of nutritional strategies and utero-ovarian functions more evaluations are needed to understand the mechanisms by which feeding PUFA may improve reproductive function in beef heifers.