Serum P4 Concentrations Research Articles

Effect of gonadorelin dose and an additional gonadorelin treatment 2 d after the initiation of Resynch-25 on ovarian dynamics and fertility of lactating Holstein cows

Our objective was to improve ovulatory response at the initiation of the Resynch-25 protocol by (1) increasing the dose of GnRH from 100 µg to 200 µg; and (2) giving a second GnRH treatment 56 h after the initiation of the protocol. We considered the experimental d 0 the day of the previous service. The experiment consisted of a 2 × 2 factorial design to compare the main effects of GnRH dose (100 vs. 200 µg) and GnRH treatment times (once vs. twice 56 h apart). A total of 2,111 previous services in 1,438 Holstein lactating cows were used. On d25, cows were assigned to receive either 100 or 200 µg of GnRH only on d25 or on d25 and 56 h later (d27). On d 32, cows diagnosed as nonpregnant (n = 1,076 services) were classified as with or without a corpus luteum (CL). Nonpregnant cows with a CL continued the Resynch-25 protocol receiving PGF2α treatments on d 32 and 33, followed by a GnRH 32 h later and timed AI 16 h after the last GnRH. Blood samples were collected in a subset of cows on d 25, 32, and 34 to assess serum P4 concentrations. In the same subset of cows, transrectal ultrasonographic examinations were performed on d 25, 29, 34 and 36 to assess ovarian parameters and ovulatory response to the GnRH treatments. The overall ovulatory response at the initiation of the protocol, defined as the ovulation between d 25 and 29, was not affected by days of GnRH treatment and averaged 41.9%. On the other hand, nonpregnant cows treated with the higher GnRH dose had a greater ovulatory response at the initiation of the protocol compared with cows treated with the lower dose (48.0% vs. 36.1%). Despite the increase in ovulatory response at the initiation of the protocol, the GnRH dose did not affect fertility of cows submitted to Resynch-25. Furthermore, the second GnRH treatment on d27 tended to decrease pregnancy per AI on d32 after AI (39.0% vs. 43.9%), but no effect of days of GnRH treatment was observed in the subsequent pregnancy diagnosis. The absence of a functional CL on d25 and ovulation at the initiation of the protocol were positively associated with improved fertility. However, the improvement in fertility of cows ovulating at the initiation of the protocol occurred only in cows with a functional CL on d25. In summary, despite increasing ovulatory response at the initiation of the protocol, the higher dose did not improve fertility. The extra GnRH on d27 did not increase ovulatory response at the initiation of the protocol and tended to decrease P/AI 32 d after AI of the Resynch-25. Also, no additive effect of the higher dose and extra GnRH treatment was observed. Despite the lack of overall treatment effect, data presented in this study suggests that the identification of CL functionality on d25 may help to optimize the resynchronization strategy used at nonpregnancy diagnosis to potentially increase fertility of cows reinseminated.

Effects of exogenous progesterone on the ovine serum progesterone profile during the non-breeding season

Exogenous progesterone (PRG) sources are used to induce ovine estrus during the non-breeding season. Intramuscular injection (IM) of PRG is an uncommon route for this purpose. This study investigated serum progesterone (P4) levels after IM administration of 50 mg of two different PRG products. Ten ewes were selected and received two consecutive PGF2α injections at 24-h intervals. Serum samples were collected (Time 0), followed by the injection of single doses of Fertigest® or Vetagesterone®. Serum P4 levels were assayed at times (T) 0, 30 min, 3,6,12,24,48,72,96, and 120 h after injection. A large variation in the serum P4 levels at T0 was detected. The serum P4 level at T0 was 4.3 ng/mL, which is considerable for anestrus ewes, following PGF2α administration. The mean time to reach maximum serum P4 concentration was 5.8 h, with a mean concentration of 22.5 ng/mL. Serum P4 levels returned to basal values (T0) after 48 h. An increased P4 production rate (PR) was detected following PRG administration, which continued for 24 h. A single injection of PRG reduced the variety of serum P4 levels from 24 h onward. The two different PRG generated different serum P4 concentrations. This study indicates an unusual change in serum P4 levels in anestrus ewes following PGF2α administration. 48 h after 50 mg PRG injection, the plasma levels of P4 reached basal levels in anestrus ewes.

Effect of post-mating administration of ketoprofen on serum progesterone concentration and fertility in Akkaraman ewes.

A major cause of early embryonic losses is inadequate secretion of progesterone (P4) hormone due to luteal insufficiency in farm animals. Post-mating applications that directly or indirectly increasing serum P4 concentrations have a positive effect on fertility. The aim of this study was to investigate the effect of post-mating administration of ketoprofen on serum P4 concentration and fertility in Akkaraman ewes synchronized with a short-term protocol during the breeding season. Oestrus monitoring ewes after synchronization were hand-mated and randomly assigned to two equal groups (Ketoprofen vs. Control). Ewes in the ketoprofen group (KPG) (n = 40) were administered with ketoprofen (Rifen, Richter pharma, Austria) intramuscularly (im) at a dose of 3mg/kg on days 9 and 10 after mating. In the control group (CG) ewes (n = 40) were administered with saline im on the same days. Blood samples were collected from ewes in both groups at four different time points of post-mating days (9, 12, 15 and 18 days). The results showed that there were no statistical differences between the KPG and CG groups on fertility parameters; pregnancy rates (85% vs. 72.5%), lambing rates (100% vs. 100%), single birth rates (55.9% vs. 55.2%), multiple birth rates (44.1% vs. 44.8%), litter sizes (1.56 vs. 1.55). In pregnant ewes, serum P4 concentrations on day 18 (4.35 ± 0.34 ng/mL) in the KPG group were higher than (3.27 ± 0.27 ng/mL) in CG group (P < 0.05). It was concluded that post-mating ketoprofen administration have no significant effect on fertility, but significantly increased the serum P4 concentration on day 18 in pregnant ewes.

Effect of post-mating GnRH or TAK-683 (Kisspeptin analog) treatment on the reproductive performance and serum progesterone concentration in ewes during the non-breeding season

This study was designed to evaluate the effect of post-mating GnRH or TAK-683 (kisspeptin analog) treatment on serum progesterone (P4) concentrations and fertility parameters of ewes during the non-breeding season. One hundred and twenty multiparous, lactating Awassi ewes were used. For estrus synchronization, vaginal sponges containing 60 mg of medroxyprogesterone acetate (MAP) were inserted into the vagina and kept there for nine days. On the day of sponge removal (day 0), 500 IU of eCG and 75 µg of d-cloprostenol were given intramuscularly. Rams were introduced in the flock 24 h after sponge removal and kept with the ewes for 26 days, allowing a second mating period after synchronized estrus. On the fourth day after mating (day 6) the ewes mated by the rams between the 24th and 72nd hours (n = 105) were randomly divided into three groups. Control group (n = 36) received 1 ml of saline solution subcutaneously; GnRH group (n = 34) received 4 μg of buserelin acetate intramuscularly; TAK-683 group (n = 35) received 5 μg of TAK-683 acetate subcutaneously. Blood samples were taken to measure serum P4 concentrations (ng/ml) at sponge insertion and on the 6th, 9th, 12th, 15th, 19th, 35th, and 50th days after sponge removal. Pregnancy diagnosis was conducted via serum P4 concentration measurement on the 19th day and transrectal ultrasonography on days 35 and 50. The results showed that GnRH treatment (4.823 ± 0.238; 2.151 ± 0.272) increased (P<0.05) the mean P4 concentration (ng/ml) in pregnant and non-pregnant ewes during the first mating period compared to Control (3.708 ± 0.207; 1.515 ± 0.164), while TAK-683 treatment (4.457 ± 0.181; 1.967 ± 0.213) was not different between groups. GnRH (58.82 %) and TAK-683 (42.10 %) treatments increased the pregnancy rate in the second mating period in comparison to the Control group (17.39 %) (P<0.05). Cumulative pregnancy and fecundity rates were higher in GnRH (79.41 %; 120.58 %) and TAK-683 (68.57 %; 100.0 %) groups than in the Control group (17.39 %; 58.33 %) (P<0.05). There was no difference in late embryonic loss rate among the groups (P>0.05), whereas early fetal loss rate tended to be lower in the TAK-683 (0 %) and GnRH (0 %) groups than in the Control group (15.38 %) (P=0.07). The total pregnancy loss rate (from day 19 to day 50 post-mating) was lower in GnRH (0 %) and TAK-683 (0 %) groups relative to the Control group (21.42 %) (P<0.05). There were no statistical differences among the groups in terms of the first mating period pregnancy rate, twinning rate, and litter size (P>0.05). As a result, treatment with GnRH and TAK-683 on the fourth day after mating increased fecundity in lactating ewes outside the breeding season by preventing total pregnancy losses (from day 19 to day 50) and increasing second mating pregnancy rates.

PROGESTERONE PROFILES OF CROSS BRED SOWS FOLLOWING DOUBLE AND TRIPLE INJECTIONS OF DINOPROST TROMETHAMINE (LUTALYSE®) TREATMENTS

This study was carried out to evaluate progesterone profile of cross bred sows in Zaria following treatments with double and triple injections of Dinoprost tromethamine (Lutalyse®). Ten (n = 10) apparently healthy cross bred sows were randomly assigned to 2 treatment groups based on number of injections of Lutalyse®. Group 1 (n=5) received two injections of Lutalyse®(12.5mg) (days 0 and 13) while Group 2 (n=5) received three injections of Lutalyse®(12.5mg) (Day 0, 7, 13). Oestrus was monitored twice daily from 0700-1000 and 1500-1800h. Data on progesterone profile obtained during the oestrous cycle were expressed as mean ± SEM. Student t-test was used to compare the mean values between the groups. Graph pad Prism®data package for windows (2009) was employed for all statistical analyses. A value of P&lt;0.05 was considered significant. There was no statistical significant (P &gt; 0.05) difference in the overall mean serum P4 concentrations between groups 1 and 2. It is concluded that dinoprost tromethamine sodium can be used to synchronize sow oestrus, both double and triple injections of dinoprost tromethamine produces similar effect on progesterone concentration. It is recommended that double injections of dinoprost tromethamines hould be used for oestrus synchronization as no statistical significant (P&gt;0.05) differences were observed in the progesterone concentrations of both groups.

P-626 Progesterone rescue is effective for clinical pregnancy outcome in women presenting low circulating progesterone levels at frozen embryo transfer day

Abstract Study question Is subcutaneous progesterone (prolutex® 25mg daily) addition effective for clinical pregnancy outcome in women presenting low progesterone(P4) levels at frozen embryo transfer(FET) day? Summary answer Subcutaneous progesterone rescue improved ongoing pregnancy rate and clinical pregnancy rate in women with low P4 results at FET day. What is known already FET has been increased, because preimplantation genetic testing for aneuploidies is performed widely, and FET presents a significantly low risk of ovarian hyperstimulation syndrome.In FET, there is no established optimal protocol for preparing endometrium, but hormonal replacement therapy (HRT) is widely used due to its convenient schedule adjustment. HRT protocol induce anovulation, functioning corpus luteum is lacking and exogenous progesterone administration is very important. Therefore, women showing low P4 levels around FET day have lower pregnancy rate. However, there are currently no data on the effectiveness of progesterone rescue. Study design, size, duration Primary outcomes from a randomized cohort retrospective study investigating subcutaneous progesterone (prolutex® 25mg) daily addition for whom had low P4 levels (&amp;lt;12ng/mL) at FET day. The study was conducted at one infertility center in Korea from January 2022 to December 2023 and pregnancy outcomes of FET transfers registered until Oct. 2023,. 194 patients fulfilled the inclusion criteria. Participants/materials, setting, methods One hundred ninety four women divided into two groups based on progesterone levels, with 12ng/ml as the threshold. Under 12ng/mL group were randomized to subgroup with and without addition of subcutaneous progesterone. In total 278 FET cycles, the effect of progesterone rescue on cumulative clinical pregnancy rate (CPR), Ongoing pregnancy rate (OPR) was reported as primary outcomes. Main results and the role of chance In total 278 cycles, there were 137 cycles with adequate serum P4 levels, while 141 cycles presented with low P4 levels in which randomly rescue subcutaneous progesterone administration added from next day of embryo transfer. When comparing the groups, there was no statistical difference in maternal age, BMI, smokers, duration of infertility, type of infertility, indication of in vitro fertilization(IVF), endometrial preparation method. In low P4 group, with and without subcutaneous progesterone addition subgroups included 51 and 90 cycles, retrospectively. CPR were 52.9% versus 35.6% (P = 0.044; chi-squared test) with a statistically significant higher rate of OPR in progesterone rescue group (45.1% versus 28.9%, p = 0.052). When comparing the group with adequate P4 levels and the group with low P4 levels without progesterone rescue, OPR were 18.2% versus 28.9% (p = 0.06, chi-squared test), CPR was significantly higher in low P4 levels group (23.4% versus 35.6%,p=0.046, chi-squared test). Adequate P4 level group had more IVF attempts (4.6 versus 2.2, p &amp;lt; 0.001, chi-squared test). There is tendency to use more luteal phase support medication with repeated attempt (serum P4 concentration on ET day 39.3 ng/mL versus 8.7 ng/mL, p &amp;lt; 0.001, t-test) Limitations, reasons for caution The main limitation of the study was retrospective, and had small sample size. A control group without progesterone rescue in low P4 levels did not receive any intervention. Wider implications of the findings The progesterone rescue for women presenting low P4 on FET day improved clinical outcome and excessively raising progesterone medication may have adverse effects. Therefore rather than using excessive progesterone administration from luteal support start day, progesterone rescue might be effective when low P4 levels presenting at FET day. Trial registration number not applicable

Effect of prostaglandin treatment on the estrus behaviour, follicular and luteal morphometry and serum hormone profile in sub-estrus buffaloes during non-breeding season.

Sub-estrus buffaloes do not exhibit estrus signs despite being cyclic contributing to extended service periods and inter-calving intervals causing significant economic loss. The present study described the effect of synthetic prostaglandin (PGF2α) on estrus behaviour, follicular and luteal morphometry, and serum estradiol (E2) and progesterone (P4) profile in sub-estrus buffaloes during the non-breeding season. The incidence of sub-estrus was 38.4% during the non-breeding season. The sub-estrus buffaloes (n = 33) were divided into two groups, viz., Control (n = 16) and PGF2α treatment (Inj. Cloprostenol 500 μg, i.m., n = 17). Estrus induction response was significantly greater in the treatment (100 vs. 18.75%, p < .001), and a relatively greater proportion of animals conceived in the treatment group (29.41 vs. 6.25%, p = .08). The time elapsed to induction of estrus and insemination following treatment was significantly lower in the treatment group than control. A significant increment in the follicle diameter (9.72 ± 0.45 vs. 13.00 ± 0.45 mm, P < .0001) and serum estradiol (E2) concentration (66.01 ± 11.92 vs. 104.9 ± 13.21 pg/mL, p = .003) observed at the post-treatment period in the PGF2α treatment group. At the same time, CL diameter was reduced significantly at a higher regression rate in the PGF2α treated buffaloes than those of control. Of the responded buffaloes, only 30% showed high-intensity estrus attributed to the expulsion of cervico-vaginal mucus (CVM), uterine tonicity, micturition, and mounting response by a teaser bull. From this study, it can be concluded that the administration of PGF2α could induce estrus in the sub-estrus buffaloes during the non-breeding season. Behavioural changes, along with sonographic observation of POF, regressing CL, and serum E2 and P4 concentration would be useful to determine the right time of insemination in sub-estrus buffaloes during non-breeding season.

Effect of prostaglandin alone and in combination with trace minerals on the follicular and luteal dynamics, estrus response and pregnancy in sub-estrus buffaloes (Bubalus bubalis).

Sub-estrus is a condition when buffaloes do not display behavioural estrus signs, despite being in estrus and causes a delay in conception and increases the service period. The present study describes the effect of synthetic prostaglandin (PGF2α) alone and in combination with trace minerals on the follicular and corpus luteum (CL) dynamics, serum estradiol (E2) and progesterone (P4) concentration correlating estrus response and pregnancy outcome in sub-estrus buffaloes during the breeding season. A total of 50 sub-estrus buffaloes, identified through ultrasonography (USG) examination, were randomly allocated into three groups, viz. T1 (Synthetic PGF2α, Inj. Cloprostenol 500 μg, i.m, n = 17), T2 (Synthetic PGF2α + Trace mineral supplementation, Inj. Stimvet 1 mL/100 kg body weight, i.m., n = 17) and control (untreated; n = 16). Following treatment, 100% of sub-estrus buffaloes were induced estrus in the T1 and T2 groups, while only 18.75% were induced in the control. The CL diameter and serum P4 concentration were significantly lower at post-treatment, whereas the pre-ovulatory follicle (POF) size and serum E2 concentration were significantly higher in the T1 and T2 groups as compared to the control (p < .05). The buffaloes of the T2 group had a greater proportion of moderate intensities estrus than those of T1. Moreover, the proportion of buffaloes conceived in the T1 and T2 were 41.2% and 52.95%, respectively. The larger POF diameter and higher serum E2 concentration were associated with intense intensity estrus and higher conception rate (66.7%) in sub-estrus buffaloes. Similarly, CL regression rate, POF size and serum E2 concentration were relatively higher in the buffaloes conceived as compared to those not conceived. It is concluded that synthetic PGF2α in combination with trace minerals induces moderate to intense intensities estrus in a greater proportion of sub-estrus buffaloes and increases the conception rate during the breeding season. Moreover, behavioural estrus attributes correlating follicle and luteal morphometry, serum E2 and P4 concentration could be used to optimise the breeding time for augmenting the conception rate in sub-estrus buffaloes.

Use of serum evaluation of contraceptive and ovarian hormones to assess reduced risk of pregnancy among women presenting for emergency contraception in a multicenter clinical trial

ObjectiveTo evaluate ovulation risk among women enrolling in an emergency contraception (EC) study by measuring contraceptive steroids and ovarian hormones. Study DesignWe used standard chemoluminescent assays to evaluate endogenous hormones [estradiol (E2), progesterone (P4), FSH, LH] and liquid chromatography-tandem triple quadrupole mass spectrometry (LC-MS/MS) to simultaneously analyze concentrations of ethinylestradiol (EE), dienogest (DNG), norelgestromin (NGMN), norethindrone (NET), gestodene (GSD), levonorgestrel (LNG), etonogestrel (ENG), segesterone acetate (NES), medroxyprogesterone acetate (MPA), and drospirenone (DRSP), in serum samples obtained at the time of enrollment in a recent study comparing oral ulipristal acetate and LNG EC in women with weight ≥ 80kg reporting no recent use of hormonal contraception. ResultsWe enrolled 532 and obtained a valid baseline blood sample from 520 women. Of these, 117 (22.5%) had detectable concentrations of a progestin [MPA (n=58, 11.2%), LNG (50, 9.6%), ENG (11, 2.1%), NET (5, 0.96%), NGMN (3, 0.06%), or DRSP (1, 0.02%)]. LNG was co-detected in all three participants with samples containing NGMN. Multiple progestins were detected in 8 other women: ENG/MPA (1); ENG/LNG (2); MPA/LNG (5). Samples from 55 (10.6%) had concentrations of one or more progestin considered above the minimum level for contraceptive [MPA ≥ 0.1ng/mL, n = 19; NGMN/LNG ≥ 0.2ng/mL, n = 31; ENG ≥ 0.09 ng/mL, n = 8; NET ≥ 0.35 ng/mL, n = 4]. We detected concentrations of serum P4 ≥ 3ng/mL, indicative of luteal phase (post-ovulation) status, in an additional 194 (37.3%) samples. ConclusionsMore than one third of enrolled in our clinical trial of oral emergency contraception had evidence of prior ovulation at the time of enrollment. Additionally, about 23% had evidence of recent use of hormonal contraception recent use of hormonal contraception. This results would have decreased the expected risk of pregnancy in the study. ImplicationsMany participants in a recent clinical trial of oral emergency contraception did not appear to be at risk for pregnancy or would not have benefited from intervention due to cycle timing. Investigators should consider the effects of these findings on expected pregnancy rates when determining sample size in future EC clinical trials, particularly when using non-inferiority designs or historical controls.Keywords

Effect of 200 μg of gonadorelin hydrochloride at the first GnRH of a CO-Synch program on ovulation rate and pregnancies per artificial insemination in Holstein heifers

The initial ovulatory response during synchronization programs is often low in dairy heifers, largely due to follicular dynamics and hormonal dynamics. Specifically, the progesterone (P4) concentration at the time of the first GnRH treatment in a breeding program can influence the LH response, often resulting in a suboptimal ovulatory response. The objective of this study was to determine the effect of the highest label dose 200 μg (100 μg vs. 200 μg) of GnRH (50 μg of gonadorelin hydrochloride per mL; Factrel, Zoetis Inc. Madison, NJ) at the first GnRH of a 6-d CO-Synch plus P4 device program on ovulatory response and pregnancy per AI (P/AI) in first service in Holstein heifers. A total of 1,308 Holstein heifers were randomly allocated at the beginning of a 6-d CO-Synch program at day 0 to receive either i.m. treatment of 100 μg (2CC, n = 655) or 200 μg (4CC, n = 653) of GnRH. Also, at d 0, heifers received an intravaginal insert with 1.38 g of P4 (Eazi-Breed CIDR Cattle Insert, Zoetis Inc.). On day 6, the insert was removed, and i.m. treatment of 25 mg of PGF2α (12.5 mg of dinoprost tromethamine/mL; Lutalyse HighCon Injection, Zoetis Inc.) was administered. On d 7, a second i.m. treatment of 25 mg of PGF2α was given, followed on d 9 by concurrent i.m. treatment of 100 μg of GnRH, and timed AI. A subset of 396 heifers had their ovaries scanned to evaluate ovulatory response, and blood samples were collected to measure the serum concentration of P4 at d 0 and d 6 of the study. The P4 concentrations at d 0 were categorized as low (≤3 ng/mL) or high (>3 ng/mL). The ovulatory response was greater for heifers receiving 4CC than 2CC at d 0 (54.7% vs. 42.8%). The ovulatory response was greater for low P4 than high P4 at d 0 (54.3% vs. 37.8%). However, we did not observe an interaction between treatment and P4 concentrations (low P4 2CC = 48.6% vs. high P4 2CC = 30.0%; low P4 4CC = 60.0% vs. high P4 4CC = 45.5%). The receiver operating characteristic curve analysis indicated that P4 concentrations at d 0 treatment could predict the ovulatory response, although the area under the curve was only 0.6. As expected, heifers that ovulated had increased P/AI (no = 55.6% vs. yes = 67.7%); however, we found no effect of treatment on P/AI (2CC = 63.3% vs. 4CC = 59.6%), and no interactions between treatment and ovulation and treatment and P4 (high vs. low) for pregnancy outcomes. In summary, P4 concentration and increasing the dose of GnRH at d 0 positively affected ovulatory response in Holstein heifers. However, there was no interaction between treatment and P4 on ovulation and no subsequent impact of GnRH dose on P/AI.

Supplementation with long-acting injectable progesterone 3days after TAI impaired luteal function in buffaloes.

Three experiments were conducted to evaluate the effects of long-acting injectable progesterone (iP4) in buffalo cows. In Experiment 1, ovariectomized buffaloes received 300mg (iP300) or 600mg (iP600) of iP4, and serum P4 concentrations were evaluated. In experiment 2, three groups were compared: control or administration of 300mg of iP4 3 (iP4-D3) or 6days (iP4-D6) after timed artificial insemination (TAI). On day 16, reproductive tract was recovered for conceptus, endometrium, and corpus luteum (CL) analysis. In experiment 3, pregnancy per AI (P/TAI) and proportion of pregnancy losses were evaluated after administration of 300mg of iP4 3 (iP4-D3) or 6days (iP4-D6) after TAI in lactating buffaloes. In experiment 1, serum P4 concentrations remained over 1ng/mL for ~ 3days in both groups. The 300mg dose was used in subsequent experiments. In experiment 2, CL weight and endometrial glands density were decreased, and conceptus length was increased in iP4-D3 compared to control and to iP4-D6 (P < 0.05). Transcript abundance of Prostaglandin F Receptor (FP) and ISG15 in CL and of ISG15 and MX1 in endometrium was greater in iP4-D3 when compared to control and to iP4-D6 (P < 0.05). In experiment 3, there was no difference among experimental groups for P/TAI at D30 and pregnancy losses (P > 0.1); however, iP4-D3 presented a lower P/TAI at day 60 (41.7%) when compared to control (56.8%) and iP4-D6 (57.7%; P = 0.07). In conclusion, administration iP4 at 3days after TAI affects CL development and consequently decreases final pregnancy outcome in buffaloes.

Effect of 200 µg of gonadorelin at the first gonadotropin-releasing hormone of the Resynch-25 on ovarian dynamics and fertility in lactating Holstein cows

Our objective was to determine the effect of a 200-µg dose of GnRH 25 d after previous artificial insemination (AI) in a Resynch-25 resynchronization program on ovulatory response, circulating progesterone (P4) concentrations before and after treatment, and pregnancy per AI (P/AI) compared with a 100-µg dose in lactating Holstein cows. Experimental d 0 was considered the day of the previous AI. Lactating dairy cows (n = 3,240) with an average of 126 d in milk (DIM) and between 1 and 6 services were randomly assigned to receive 100 µg or 200 µg of GnRH on d 25 (GnRH25). On d 32 after AI, cows diagnosed nonpregnant with the presence of a corpus luteum (CL) detected by ultrasound (n = 1,249) received PGF2α treatments on d 32 and 33, followed by a GnRH 32 h later and AI 16 h after this last GnRH. Blood samples were collected on d 25, 32, and 34 to evaluate serum P4 concentrations. Transrectal ultrasonographic examination was performed on d 25 and 27 to assess ovulatory response to GnRH25. Cows were checked for pregnancy on d 32, 46, and 88 after AI. The larger dose of GnRH increased the overall proportion of cows that ovulated to the GnRH25 (25.0% for the 100-µg dose vs. 32.5% for the 200-µg dose). However, when cows were evaluated separately according to the pregnancy status on d 32 after AI, we found no treatment effect within cows pregnant and nonpregnant. Even though treatment increased the proportion of cows with serum P4 ≤0.42 ng/mL at the last GnRH treatment (G2; 86.2% for the 100-µg dose vs. 93.0% for the 200-µg dose), it did not affect P/AI on d 32, 46, and 88. Furthermore, a greater proportion of cows without a functional CL at GnRH25 had circulating P4 concentrations ≥1.00 ng/mL on d 32 and lower than 0.42 ng/mL on G2. These cows also had a greater P/AI on d 32, 46, and 88. In summary, the larger dose of GnRH on d 25 after AI did not increase the ovulatory response in nonpregnant cows and P/AI on d 32, 46, and 88 after AI after the Resynch-25 program. Additionally, nonpregnant cows without a functional CL at GnRH25 were better synchronized after the Resynch-25 protocol and had greater P/AI on d 32, 46, and 88 after timed-AI.

Associations of postpartum health with progesterone after insemination and endocrine signaling during early pregnancy in dairy cows

Our objective was to investigate associations of postpartum health with serum progesterone (P4) concentrations after first artificial insemination (AI), expression of interferon-stimulated genes (ISG) in blood leukocytes, and serum pregnancy-associated glycoprotein (PAG) during early pregnancy in dairy cows. In this observational study, Holstein cows (n = 475) from 2 commercial herds were enrolled 3 wk before expected parturition. Body condition score (BCS) and lameness were assessed at enrollment, and total Ca, haptoglobin, and nonesterified fatty acids (NEFA) were measured in serum at 2 and 6 ± 2 d in milk (DIM). Blood β-hydroxybutyrate and metritis were evaluated at 4, 8, 11, and 15 ± 2 DIM, and purulent vaginal discharge (PVD) and endometritis based on endometrial cytology were diagnosed at 35 DIM. Onset of cyclicity was assessed by biweekly P4 measurements. The BCS was assessed at enrollment and at 63 DIM, and lameness at enrollment and at 21 and 49 DIM. First AI was based on estrus detection until ∼75 DIM, or synchronization for timed AI thereafter. Serum P4 was measured at d 8 and 12 after first AI; expression of ISG (ISG15 and RTP4) in blood leukocytes was assessed at d 19; and PAG in serum of pregnant cows was measured at d 29, 33, and 40. Multivariable linear regression models were built including health variables (with metabolites categorized via receiver operating characteristic curve analysis) and covariates (season, milk yield, AI method, DIM), accounting for pregnancy status (for ISG and PAG models), repeated measures (for P4 and PAG models), and herd as random. Results are reported comparing cows affected versus unaffected by each predictor. Serum P4 concentrations were lesser at d 8 after AI in cows that had total Ca ≤2.09 mM (3.6 vs. 4.0 ± 0.2 ng/mL) at 2 DIM or a clinical disease (3.7 vs. 4.0 ± 0.2 mg/mL), and P4 tended to be lesser at d 8 in cows that had PVD (3.6 vs. 4.0 ± 0.2 ng/mL) or any uterine disease (3.7 vs. 4.1 ± 0.2 ng/mL). Among cows pregnant at d 29, relative ISG15 expression (fold change) at d 19 was greater in cows that had lameness (5.10 [4.18-6.18] vs. 3.14 [3.10-3.19]) but tended to be lesser in cows that had endometritis (3.20 [2.89-3.54] vs. 4.29 [4.20-4.35]), and relative expression of RTP4 tended to be lesser in cows that had displaced abomasum (1.02 [0.62-1.67] vs. 1.75 [1.73-1.78]). Serum PAG was lesser at d 29 (3.8 vs. 4.2 ± 0.2 sample-to-positive ratio [S:P]) in cows that had NEFA ≥0.73 mM at 6 DIM, and lesser at d 33 (3.9 vs. 4.5 ± 0.2 S:P) and 40 (3.1 vs. 3.7 ± 0.2 S:P) in cows that had prepartum BCS ≥3.75. These findings suggest long-term effects of metabolic or reproductive tract disorders on luteal function after first AI, pregnancy recognition signaling, and placental function during early pregnancy. These associations may partially explain some of the pathways linking postpartum health and fertility in dairy cows.

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

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

Reproductive performance in gilts submitted to non-steroidal therapies to prolong the luteal phase of the estrous cycle

Synchronized cyclicity of replacement gilts is crucial to optimize breeding herd management, however, protocols with oral progestogen are expensive and require daily administration. This study tested two synchronization protocols without progestogens during the luteal phase in gilts. In Experiment I, on the day of the expression of the third estrus (D0), gilts were assigned to three groups (n = 6, each): control, with no treatment; PGF25: in which gilts received two doses of hCG (1,500 IU each) on D12 and D15 and two doses of a prostaglandin F2α (PGF) analogue (sodium cloprostenol; 250 µg) 6-h apart, on D25; and PGF30: in which gilts received two doses of hCG (1,500 IU each) on D12 and D15 and two doses of the PGF analogue (sodium cloprostenol; 250 µg) 6-h apart, on D30. The interval between PGF treatment and estrus expression was shorter in PGF30 than in PGF25 (P < 0.01). The PGF treatment failed to decrease serum progesterone (P4) for gilts from the PGF25 group (P > 0.05), but it was effective for gilts in the PGF30 group (P = 0.01). In Experiment II, gilts were assigned to three groups (n = 12, each): control (no treatment); eCG+hCG (400 IU eCG on D10 plus 500 IU hCG on D12); and hCG2 (two hCG doses, 1,500 IU each on D12 and D15). On D30, gilts from eCG+hCG and hCG2 that did not express estrus received two doses of the PGF analogue (250 µg each, 6-h apart). All gilts were inseminated when estrus was detected. Serum P4 concentrations were similar for all groups on D10 (P > 0.05) and greater on D20 and D25 for gilts in eCG+hCG and hCG2 (P < 0.01) than for those in the control, whereas P4 concentration was greater in hCG2 than in eCG+hCG, on both moments. The inter-estrus interval (IEI) was shorter for control gilts and intermediate for gilts in eCG+hCG, while the longest IEI was observed for gilts in hCG2 (P < 0.01). Total litter size was larger for gilts in the control (P = 0.02) compared to those in hCG2 and did not differ from the other groups for gilts in eCG+hCG (P > 0.05). In conclusion, Experiment I showed that PGF treatment did not induce luteolysis 10 days after the second hCG treatment but it was effective 15 days after the second hCG application. Additionally, Experiment II showed that both eCG+hCG and hCG2 were efficient in prolonging the luteal phase; however, number of piglets born alive and total litter size were negatively affected by the hCG2 protocol. In this sense, treatment with eCG+hCG or hCG2 may represent a steroid-free approach to prolong the luteal phase in gilts, although the doses and number of treatments must be further investigated.

Fertility in seasonal-calving pasture-based lactating dairy cows following timed artificial insemination or timed embryo transfer with fresh or frozen in vitro–produced embryos

The objective was to compare pregnancy per service event (P/S) in lactating dairy cows following timed artificial insemination (AI) or timed embryo transfer (ET) using either fresh or frozen in vitro-produced embryos. Oocytes were collected once per week for up to 9 wk using transvaginal ovum pick-up from elite dairy donors (ET-DAIRY; n = 40; Holstein-Friesian and Jersey) and elite beef donors (ET-ELITE-BEEF; n = 21; Angus). Both ET-DAIRY and ET-ELITE-BEEF donors consisted of heifers and cows. In addition, oocytes were collected from the ovaries of beef heifers of known pedigree following slaughter at a commercial abattoir (ET-COMM-BEEF; n = 119). Following in vitro maturation and fertilization, presumptive zygotes were cultured in vitro to the blastocyst stage. Grade 1 blastocysts were either transferred fresh or frozen for on-farm thawing and direct transfer. A total of 1,106 recipient cows (all lactating, predominantly Holstein-Friesian) located on 16 herdlets were blocked based on parity, calving date, and Economic Breeding Index, and randomly assigned to receive AI (n = 243) or ET (n = 863) after estrous synchronization with a 10-d Progesterone-synch protocol. Cows assigned to ET were further randomized to receive fresh (n = 187) or frozen (n = 178) ET-ELITE-BEEF embryos, fresh (n = 169) or frozen (n = 162) ET-DAIRY embryos, or fresh (n = 80) or frozen (n = 87) ET-COMM-BEEF embryos. Pregnancy was diagnosed using transrectal ultrasound on d 32 to 35 after synchronized ovulation and confirmed on d 62 to 65, at which time fetal sex was determined. Pregnancy per service event at d 32 was not different between AI (48.8%) and ET (48.9%) and did not differ between dairy and beef embryos (50.3% vs. 48.1%, respectively). However, P/S was less on d 32 following transfer of frozen embryos (41.6%) compared with fresh embryos (56.1%). Pregnancy loss between d 32 and 62 was greater for ET (15.1%) compared with AI (4.7%), with greater losses observed for frozen beef (18.5%), fresh beef (17.3%), and frozen dairy (19.2%) compared with fresh dairy (6.0%) embryos. Serum progesterone (P4) concentration on d 7 was associated with P/S at d 32 and 62. Cows in the quartile with the least serum P4 concentrations (quartile 1) had less probability of being pregnant on d 32 (33.4%) compared with cows in the 3 upper quartiles for serum P4 (45.7%, 55.6%, and 61.2% for quartile 2, quartile 3, and quartile 4, respectively). Sex ratio (male:female) at d 62 was skewed toward more male fetuses following ET (61.1:38.9) compared with AI (43.2:56.8) and was consistent with the sex ratio among in vitro blastocysts (61.2:38.8). In conclusion, P/S was similar for AI and ET, although pregnancy loss between d 32 and 62 was greater for ET than for AI.

Effect of using 200 μg of gonadorelin at the first gonadotropin-releasing hormone of the breeding-Ovsynch on ovulatory response and pregnancies per artificial insemination in first-service lactating Holstein cows

This study aimed to determine whether 200 μg of GnRH (gonadorelin hydrochloride) would increase ovulatory response and pregnancies per artificial insemination (P/AI) compared with 100 μg at the first GnRH of the breeding-Ovsynch of a Double-Ovsynch program (DO) in lactating Holstein cows. Weekly cohorts of primiparous (n = 719) and multiparous (n = 1,191) cows submitted to DO (GnRH, 7 d later PGF2α, 3 d later GnRH, 7 d later GnRH [G1], 7 d later PGF2α [PG1], 1 d later PGF2α, ∼32 h later GnRH [G2], and ∼16 h later timed artificial insemination [TAI]) for first service, randomly received either 100 μg or 200 μg of GnRH (gonadorelin hydrochloride) at G1 (primiparous, 64-75 DIM; multiparous, 59-70 DIM). Ovulation was determined by ultrasound 2 d after G1 (n = 1,294) and 2 d after G2 (n = 1,020). Blood samples were collected at G1 and at PG1 d to evaluate serum progesterone (P4) concentrations. Conventional (n = 314, Angus; n = 1,084, Holstein) and Holstein sexed semen (n = 276) were used. Pregnancy was diagnosed on d 32, 46, 88, and 200 post-TAI. The high dose of GnRH (200 μg) increased overall ovulatory response to G1 compared with 100 μg (81.3% vs. 65.1%), being similar between parities (primiparous, 72.2%; multiparous, 73.9%). Mean serum P4 concentrations at PG1 did not differ between treatments (100 µg: 9.59 ± 0.15 ng/mL vs. 200 µg: 9.43 ± 0.15 ng/mL). Cows with no ovulation to G1 had higher serum P4 concentrations at G1 than cows with ovulation to G1 (6.27 ± 0.19 ng/mL vs. 4.66 ± 0.07 ng/mL). At PG1, the proportion of cows with functional corpus luteum (98.7% vs. 89.7%) and serum P4 concentrations (9.68 ± 0.12 ng/mL vs. 9.14 ± 0.22 ng/mL) were greater in cows that ovulated to G1 compared with cows that did not ovulate. Also, cows that ovulated to G1 had a greater increase in serum P4 concentrations from G1 to PG1 than cows with no ovulation (5.26 ± 0.12 ng/mL vs. 3.32 ± 0.25 ng/mL). The high dose of GnRH improved overall P/AI at 32 d post-TAI in cows inseminated with conventional semen (54.6% vs. 48.2%) and tended to improve P/AI on 46 (48.8% vs. 44.9%), 88 (47.6% vs. 43.4%), and 200 (45.3% vs. 41.2%) d post-TAI. Primiparous cows inseminated with conventional semen had better P/AI than multiparous cows at d 32 (58.2% vs. 49.4%), 46 (55.1% vs. 44.4%), 88 (53.2% vs. 43.2%) and 200 (51.6% vs. 40.7%) post-TAI. Primiparous cows treated with 200 µg GnRH had lower P/AI on d 32, 46, 88, and 200 post-TAI when inseminated with sexed semen than with conventional semen. In summary, the higher dose of GnRH at G1 improved ovulatory response and P/AI at d 32 post-TAI and tended to improve P/AI at d 46, 88, and 200 post-TAI in cows inseminated with conventional semen. Moreover, the effect of treatment on P/AI in primiparous cows depended on semen type (conventional vs. sexed semen).

Effect of hCG administration on ovulation and estrus in Saanen goats subjected to short-term estrus synchronization protocol during the breeding season

This study aimed to compare the effect of hCG administered at 24 or 36 h following a short-term estrus synchronization treatment on the ovulation time and estrus parameters in non-lactating Saanen goats during the breeding season. The estrous cycles of does were synchronized with an intravaginal sponge containing 60 mg of medroxyprogesterone acetate (MAP) for six days, and an injection of 125 µg of d-cloprostenol at the time of sponge insertion in addition to an injection of 300 IU of eCG 24h before sponge removal. After removal of the sponges, does were injected intramuscularly either 1 ml physiological saline (0.9% NaCl) solution after 12 h (Group1/Control; n=10), 100 IU hCG after 24 h (Group2; n=9) or 100 IU hCG after 36 h (Group3; n=9). Estrus behavior after sponge removal was observed twice daily for 84 h using teaser bucks and transrectal ovarian ultrasonography was performed twice a day for seven days to determine small, medium and large follicle numbers, luteal development and the time of ovulation. Blood samples were collected on the same days to determine serum progesterone (P4) and estradiol (E2) concentrations. No significant differences were observed in terms of estrus parameters, ovarian structure and serum P4 and E2 concentrations between the hCG-treated groups and the control group. Average values observed for all groups: estrous response (53.57%), the interval from sponge removal to estrus and ovulation (35.2 h and 67.86 h, respectively), duration of estrus (18.4 h), the interval from estrus onset to ovulation (50.37 h), ovulation rate (96.43%), number of ovulations (1.36), ovulatory follicle diameter (6.86 mm), corpus luteum diameter (8.22 mm), follicle and luteal growth rate (1.17 and 0.68 mm/day, respectively). In conclusion, administration of hCG at 24 or 36 h following a short-term estrous synchronization protocol does not affect ovulation time, estrus parameters, and serum P4 and E2 concentrations in goats during the breeding season.

Short-term clinical and hormonal effects of a deslorelin implant on late-prepubertal bitches – Based on flare-up signs

Gonadotropin-releasing hormone (GnRH) agonists offer an alternative to surgical sterilization in prepubertal dogs, preserving ovarian and uterine functions. However, the clinical and hormonal effects of GnRH agonist application during the late-prepubertal stage remain insufficiently understood. This study aimed to investigate the clinical effect (flare-up) and hormonal changes, specifically serum progesterone (P4) and estradiol (E2) levels, in bitches treated with 4.7 mg deslorelin acetate (DA) implants (Suprelorin®, Virbac, F) during the late prepubertal period. Sixteen clinically healthy kangal cross-breed bitches, aged 7–8 months, with a mean body weight of 20.5 ± 0.8 kg, were implanted with DA. Estrus signs were monitored daily, and blood and vaginal cytological samples were collected every other day for four weeks. Cytological changes were analyzed for overall and superficial cell index. Six out of sixteen DA-treated bitches (EST group; n = 6) exhibited clinical proestrus 8.6 ± 0.6 days after implant insertion. The mean serum concentrations of P4 and E2 at the onset of estrus were 1.38 ± 0.32 ng/ml and 37.38 ± 10.07 pg/ml, respectively. Notably, all non-estrus (N-EST group; n = 10) bitches demonstrated an increase in superficial cell index, in addition to expected cytological changes observed in the EST group. On the 18th day post-implantation, the EST group exhibited a significantly higher number of superficial cells compared to the N-EST group (p < 0.001). DA implantation resulted in cytological profile alterations accompanied by a slight increase in estrogen concentrations in all dogs. However, the flare-up response exhibited significant variability, differing from that observed in adult dogs. This study highlights the importance of meticulous timing and breed-specific considerations when utilizing DA for puberty manipulation in late-prepubertal bitches. The observed cytological and hormonal changes in response to DA implants provide valuable insights, but the variability in flare-up responses warrants further investigation.

Long-acting injectable progesterone treatment prior to puberty induction in gilts

Progesterone (P4) has a pivotal role on female puberty attainment in most farm animals. However, there are no studies evaluating the effect of P4 treatment previously to boar exposure for puberty induction in gilts. Therefore, serum P4 concentration, estrus expression and reproductive performance after boar stimuli were evaluated in gilts intramuscularly treated with long-acting P4 before boar exposure. In Experiment I, prepubertal gilts received either 1 mL of saline (control) or intramuscular (I.M.) P4 treatment (150 mg, 300 mg or 600 mg; n=6 per treatment). Serum P4 concentration for P4-treated gilts was greater than for control gilts for at least 8 d for P4300 and P4600 groups (P < 0.05), but greater until after 16 d only for those treated with 600 mg (P < 0.05). In Experiments II (prepubertal) and III (peripubertal), gilts received either saline (control) or 300 mg P4 I.M. and those showing estrus signs were artificially inseminated (AI), whereas gilts without estrus expression were culled. In prepubertal gilts (Exp. II), estrus expression rate did not differ (P < 0.05) for control (79.1%; n=110) and P4-treated gilts (81.5%; n=108). In peripubertal gilts (Exp. III), although estrus expression did not differ between control (77.6%; n=106) and P4-treated (69.6%; n=102) gilts (P > 0.05), P4-treated gilts presented longer (23.1 ± 1.4 days) interval from treatment to estrus expression than control gilts (17.1 ± 1.3 days; P < 0.05). In Experiments II and III, the proportion of culled gilts with ovarian structures consistent with normal estrous cycles, farrowing rate, and litter size did not differ between treatments (P > 0.05). In conclusion, I.M. treatment with 300 or 600 mg of long-acting P4 was efficient in maintaining high P4 concentrations in prepubertal gilts for at least 8 days. However, P4 treatment over this time interval did not benefit the reproductive performance of prepubertal and peripubertal gilts.