Intravaginal Progesterone Device Research Articles

Equine chorionic gonadotropin (eCG) treatment in heifers: Double ovulation, twinning rate, and pregnancy losses in twin pregnancies

This study aimed to evaluate the effects of different doses of equine chorionic gonadotropin (eCG; 200 and 300 IU) administered at the end of a fixed-time artificial insemination (FTAI) treatment protocol on ovulation, pregnancy, and twin rates in Bos taurus beef heifers. In addition, pregnancy losses in heifers with singleton and twin pregnancies were determined. A total of 2382 Angus heifers treated with a 6-day estradiol/progesterone-based protocol for FTAI (J-Synch protocol) were randomly allocated to two experimental groups to receive 200 or 300 IU of eCG administered intramuscularly at the time of intravaginal progesterone device removal; FTAI was performed from 60 to 72 h after device removal. The pregnancy rate did not differ (P = 0.89) between the 200 and 300 IU eCG groups. The number of corpus luteum induced by both eCG doses was determined by ultrasonographic examination 14 days after insemination and those treated with 300 IU of eCG had a greater double ovulation rate (P < 0.05). In addition, 300 IU eCG treated heifers had a higher twinning rate on day 30 of gestation (P < 0.05) and parturition (P < 0.05). Pregnancy losses from 30 days of gestation to calving did not differ between heifers treated with 200 and 300 IU of eCG (P = 0.70). However, regardless of the experimental group, heifers bearing twins had greater pregnancy losses than heifers with singletons (P < 0.05). In conclusion, reducing the dose of eCG from 300 to 200 IU under FTAI treatment protocol decreases double ovulation and twinning rates, maintaining a similar pregnancy rate in heifers. Nulliparous cows carrying two fetuses suffer greater pregnancy losses than cows with singletons.

Timed-artificial insemination protocols for Bos indicus beef heifers: Evaluation of protocol length and variations in prostaglandin F2α treatments

The aim was to compare reproductive outcomes of Nelore heifers submitted to timed AI (TAI) protocols, with 7 or 9 d of permanence of the intravaginal progesterone (P4) device and different times of prostaglandin F2α (PGF) administration, for first (n = 935) and second (n = 530) services. On Day −24, heifers without corpus luteum (CL) underwent a protocol for induction of ovulation. On Day 0, heifers received a P4 device (0.5 g) and 1.5 mg estradiol (E2) benzoate. In order for the TAI to be carried out on the same day, these treatments were performed 2 d later on the heifers treated with the 7-d protocol. Additionally, heifers received 0.5 mg PGF at different times, resulting in four experimental groups: 9dP4-PGFd9 (n = 365); 9dP4-PGFd7 (n = 369); 9dP4-PGFd0&9 (n = 364); 7dP4-PGFd0&7 (n = 367). These nomenclatures indicate for how many d the P4 device was kept and the specific day on which PGF was given. At P4 removal, all heifers received 0.5 mg E2 cypionate and 200 IU eCG, and TAI was performed 2 d later. Effects were considered significant when P ≤ 0.05 (superscript letters a,b) whereas a tendency was assumed when 0.05 < P ≤ 0.10. Groups 9dP4-PGFd0&9 and 7dP4-PGFd0&7 had lower percentage of heifers with CL at P4 removal. The diameter (mm) of the dominant follicle (DF) was affected by treatment at P4 removal (9dP4-PGFd9: 11.3 ± 0.3b; 9dP4-PGFd7: 11.8 ± 0.2ab; 9dP4-PGFd0&9: 12.6 ± 0.2a; 7dP4-PGFd0&7: 10.8 ± 0.2c) and at TAI (9dP4-PGFd9: 12.7 ± 0.3ab; 9dP4-PGFd7: 13.2 ± 0.2a; 9dP4-PGFd0&9: 13.4 ± 0.2a; 7dP4-PGFd0&7: 12.4 ± 0.3b). Expression of estrus (%) was affected by treatment (9dP4-PGFd9: 89.6a; 9dP4-PGFd7: 93.5a; 9dP4-PGFd0&9: 88.2ab; 7dP4-PGFd0&7: 85.6b). There were no differences among treatments for P/AI on Day 40 (30–35 d post AI), final P/AI (between Day 70 and parturition) and pregnancy loss (between Day 40 and final P/AI). When the permanence of the P4 device was compared, regardless of PGF treatments, 9-d protocols resulted in greater DF diameter at P4 removal and at TAI, and greater expression of estrus (90.4 vs. 85.6%) than the 7-d protocol. Despite that, the 7-d protocol resulted in greater P/AI on Day 40 (55.3 vs. 49.1%). In addition, there was an interaction between protocol duration and body weight, in which heavier heifers (≥ 307 kg) had greater P/AI when treated with the 7-d protocol, in comparison to 9-d. In conclusion, longer TAI protocols (9 d of P4 device duration) resulted in greater DF diameter and expression of estrus. However, the shorter TAI protocol (7 d of P4 device duration) produced greater P/AI on Day 40, particularly in heavier heifers. Within 9-d protocols, the additional dose of PGF on Day 0 or the anticipation of the PGF to Day 7 did not influence fertility.

The potential of biodegradable polymers: Chitosan, polyethylene glycol, and polycaprolactone as materials for progesterone intravaginal devices

&lt;p&gt;&lt;span lang="EN-US"&gt;For several decades, a protocol based on the use of progestagens has been used to manage livestock reproduction with minimal alterations. Recently, researchers have gained insight into the short-term use of progestagen protocols lasting 5-7 days, which has been found to reduce the incidence of vaginitis and obviate the use of antibiotics. Additionally, this approach enables the reutilization of silicone-based devices such as CIDRs after a thorough biosecurity assessment. However, these devices have certain limitations. At the end of the treatment, they must be disposed of and cannot be reused, necessitating a re-evaluation of their use for technical and societal reasons, including animal health and welfare, food safety, and environmental impact.&lt;/span&gt;&lt;span lang="EN-US"&gt;A chitosan-PEG intravaginal implant formulation released progesterone for a period of four days, corresponding to the degradation time of the implant in the vagina. The use of a simple melting and molding process for the combination of PCL-PEG-chitosan implants has been observed to result in degradation of both simulated vaginal fluid and vaginal tissue of cows. The development of intravaginal devices made from biodegradable polymers is considered a potential solution because these materials would degrade within the body, eliminating the need for removal and leaving no residue. These devices are safe for animals and the environment.&lt;/span&gt;&lt;/p&gt;

PSII-10 Effect of Equine Chorionic Gonadotrophin-Like Glycoprotein Treatment on Fertility in Angus Cows Subjected to a 7-Day Co-Synch Protocol

Abstract This study evaluated the effect of administering a glycoprotein with equine chorionic gonadotropin like activity produced by recombinant DNA technology (eCG-like) associated with a 7-d Co-Synch protocol on estrus rate (ER) and pregnancy per timed AI (P/TAI). A total of 1,344 suckled Angus cows (primiparous, n = 381; multiparous, n = 963) from 11 herds were scanned at initiation of synchronization protocol by transrectal ultrasonography and the presence of corpus luteum (CL) and uterine tone was used to classify them by cycling. On day -10, cows received 100 μg GnRH analogue and a progesterone intravaginal device (IVD; 1.0g progesterone) for 7 days. At IVD removal, cows were administered 500 μg of cloprostenol and randomly assigned to receive 400 IU of eCG-like glycoprotein (Syntex S.A., Argentina, PCT/EP2019/073277; eCG-like, n = 665) or to remain as untreated (Control, n = 679). Also on day -3, paint was applied on the sacrum to the tail head of each cow. Finally, 100 μg GnRH analog were injected concurrently with TAI on Day 0 (66h after IVD removal) and the ER was evaluated by the degree of paint loss. Pregnancy to TAI was determined on day 30 by transrectal ultrasonography when an embryo and fluid were detected in the uterus. Body condition score (BCS; scale = 1-9) was evaluated on days -10 and 30. Optimal BCS was considered ≥ 5 and BCS balance between days -10 and 30 was classified as negative (lost BCS) or positive (maintained or gained BCS). The associations among treatment, parity, cyclicity at initiation of protocol, optimal BCS on day -10, and their interactions and ER and P/TAI were analyzed by GLIMMIX (SAS 9.3). Estrus expression and BCS balance were also included as effects in the model of pregnancy per TAI. The effect of herd was included as a random effect. The model specifications included an option to retrieve the mean, SEM, and an adjustment for multiple comparisons (Tukey-Kramer). The percentage of acyclic cows was 31.3%. The ER in cyclic cows was 64.9% and the eCG-like treatment increased ER only in anestrus cows (55.8 vs. 44.3%; Treatment x cyclicity interaction; P = 0.03). The percentage of cows with negative BCS balance was 27.2%. The P/TAI in cows with positive BCS balance was 48.4% and the eCG-like treatment increased P/TAI only in cows with negative BCS balance (44.7% vs. 30.5%; Treatment x BCS balance interaction; P = 0.01). In conclusion, the addition of a recombinant eCG-like glycoprotein to a 7-day Co-Synch protocol increased estrus expression in anestrus Angus cows and P/TAI in those with negative body condition score balance. However, this addition did not influence the estrus expression in cycling cows or on P/TAI in those with positive BCS balance.

Intravaginal progesterone device reinsertion during the early luteal phase affects luteal function and embryo yield in superovulated ewes

This study checked the efficacy of progesterone (P4) device reinsertion during the early luteal phase on luteal function and embryo yield in superovulated crossbred ewes. Twenty multiparous ewes received an intravaginal P4 device for nine days (D0 to D9) followed by six decreasing doses (25, 25, 15, 15, 10, 10%) of 133 mg pFSH i.m. at 12 h intervals, starting 60 h before P4 device removal. Ewes were naturally mated at 12 h intervals while in estrus. On D13, ewes with viable corpora lutea (CL; n = 19) were equally allocated for receiving their P4 device reinsertion (G-P4; n = 10) or not (G-Control; n = 9). On D17, the P4 device was removed, and all females received the cervical relaxation protocol 16 h to 20 min before non-surgical embryo recovery. CL count and their functionality classification were performed on D13 and D17 by transrectal B-mode and color Doppler ultrasonography (US). Plasma P4 concentrations (ng/mL) of G-P4 ewes increased (P < 0.05) over the days, being greater on D17 (9.2 ± 2.8) than on D9 (1.9 ± 0.7) and D13 (1.6 ± 0.4). The overall CL count per ewe tended to be greater (P = 0.09) in G-P4 compared with G-Control. The occurrence of premature regression of corpora lutea did not differ (P > 0.05) between G-P4 (30.0%) and G-Control (44.4%). The number of ova/embryos recovered was greater (P < 0.05) in G-P4 (11.6 ± 2.9) compared with G-Control (3.7 ± 2.0), respectively. Altogether, the reinsertion of the P4 device for four days after superovulation in ewes promotes greater P4 concentrations, resulting in greater ova/embryos recovered.

Factors affecting pregnancy rates in acyclic recipient mares prepared with an intravaginal progesterone device

In acyclic embryo recipient mares, artificial cycle protocols are conventionally based on estradiol followed by long acting (LA) progesterone injections. The use of intravaginal devices has been encouraged because it allows a rapid resynchronization of recipients (Rigoleto-Júnior et al., Journal of Equine Veterinary Science 2021; 97:103325) and days of estradiol injections have also been discussed (Silva et al., Journal of Equine Veterinary Science 2021; 103:103669), but further studies are needed to develop more appropriate protocols. The present work aimed to evaluate factors that affect fertility in a commercial ET program. A total of 114 healthy mares (5-15yr-old) were used as embryo recipients and divided into two groups according to ovarian activity: cyclic (n=57) and acyclic (n=57, anestrus or transitional). Day-0 was defined as the day of ovulation in the cyclic group and the day of a 1g intravaginal P4 device (iP4) insertion in the acyclic group. Before iP4 insertion, 17β-estradiol doses varied from 0 to 10mg daily depending on the presence of natural or induced uterine edema that ranged from 3 to 7 days in duration. A one-by-one Pearson's Chi-square test was used to compare pregnancy rates between groups and the effects on pregnancy rate of 1) number of days of 17β-estradiol injections, 2) uterine edema (0-4 score)on D0 in the acyclic group, and 3) day of ET in both groups. Plasma P4 concentrations were evaluated daily by RIA in acyclic (n=10) and cyclic (n=13) mares from D0 to D7. Repeated measure models followed by Tukey's test were used to compare mean plasma P4 within groups. Pregnancy rates did not differ between acyclic (82%, 47/57) and cyclic (75%, 43/57) mares (P=0.5). Uterine edema on Day 0 (P=0.7) and day of ET (P=0.05) did not affect pregnancy rates of acyclic mares. Three days of estradiol treatment in acyclic mares resulted in a lower pregnancy rate (P=0.0425) than four days of injections. For cyclic recipient mares, day of ET affected pregnancy rates (P=0.0001) where D4 (96%, 26/27) showed higher pregnancy rates than D5 (66.7%, 12/18) and D6-7 (41.7%, 5/12), but D5 and D6-7 did not differ. Mean plasma P4 concentrations varied over days for both groups (P>0.05). In cyclic mares, mean plasma P4 increased daily to D5 (plasma P4 = 10ng/mL) followed by a plateau, whereas in the acyclic group, iP4 insertion caused an abrupt rise in plasma P4 concentration within 24h (plasma P4=5.67mg/mL) followed by a gradual daily fall to D7 (plasma P4=2.78mg/dL). In conclusion, the use of acyclic recipient mares prepared with iP4 results in similar pregnancy rates as in cyclic mares despite differences in the plasma P4 profile.

Effects of two protocols of ovulation synchronization on corpus luteum size and blood flow, progesterone concentration, and pregnancy rate in beef heifers

The objective of this study was to evaluate the effect of 7-day estradiol-progesterone-based [Treat(C)] and 5-day Co-Synch plus progesterone [Treat(Co-Sy)] protocols on ovulation time, pre-ovulatory follicle diameter, corpus luteum (CL) size and blood flow, progesterone (P4) concentration and pregnancy rate (PR) in beef heifers. In Experiment 1, a crossover design was applied (n = 9). For Treat(C), a progesterone intravaginal (PI) device was inserted, plus 2 mg of estradiol benzoate (day 0). On day 7, 500 µg of cloprostenol plus 0.5 mg of estradiol cypionate were administered, and PI was removed. For Treat(Co-Sy), on day 0, a PI was inserted plus 100 µg gonadotropin-releasing hormone (GnRH). On day 5, PI was removed, plus 500 µg of cloprostenol and 100 µg of GnRH were administered at 69–70 h later. From day one to ovulation day, dominant follicle was evaluated by ultrasonography. On days 4 and 8 post-ovulation, CL was evaluated by color Doppler, and P4 concentration was determined by chemiluminescence. In Experiment 2, a split-plot experimental design was used. Protocols followed were the same as in Experiment 1 [Treat(C); n = 310 and Treat(Co-Sy); n = 314]. Heifers were fixed-time artificially inseminated. Pregnancy was determined on day 41. In Experiment 1, the interval between PI removal and ovulation time was different between protocols (P < 0.01). In addition, P4 concentration was related to the CL size (P < 0.001), CL blood flow (P < 0.01) and protocols (P < 0.03). In Experiment 2, PR did not differ between protocols.

Administration of Beta-Nerve Growth Factor during the Preovulatory Stage Improves Endocrine and Luteal Function in Dairy Heifers

The neurotrophin beta-nerve growth factor (NGF), which is present in the semen of different mammals, elicits potent ovulatory and luteotrophic actions in llamas following systemic administration. Here, we determine if purified NGF given intramuscularly (IM) during the preovulatory stage affects the corpus luteum (CL), hormone production, endometrial gene expression, and pregnancy rate of dairy heifers. Holstein-Friesian heifers were estrus-synchronized using estradiol benzoate (EB) plus an intravaginal progesterone (P4) device (DIB). After eight days, the device was removed and cloprostenol was given IM; the next day (day 9), heifers received EB IM plus one of the following: (i) 1 mg of NGF (NGF D9 group), (ii) 1 mg of NGF 32 h after EB (NGF D10 group), or (iii) phosphate buffer saline (control group). To measure pregnancy rates, heifers were treated similarly, then artificially inseminated with sexed semen 48-52 h after DIB removal, then an ultrasound was conducted 30 days after insemination. The females given NGF along with EB (NGF D9) showed significantly higher luteinizing hormone (LH) concentrations, larger CL vascular areas, and higher plasma P4 concentrations than the NGF D10 and control animals. Downregulation of the P4 receptor (PGR), and upregulation of both lipoprotein lipase (LPL) and Solute Carrier Family 6 member 14 (SLC6A14) endometrial genes, were detected in NGF D9 heifers. Furthermore, these heifers had a 10% higher pregnancy rate than the control group. We conclude that the higher P4 output, in response to the early NGF administration, led to the enhanced gene expression of transcripts related to uterine receptivity that may result in enhanced pregnancy rates.

GnRH dose at initiation of a 5-day CO-Synch + P4 for fixed time artificial insemination in suckled beef cows

The objective of the present study was to evaluate the effect of GnRH dose administered at initiation (GnRH-1) of a 5-day CO-Synch + P4 protocol on ovulatory response, expression of estrus, and fertility in suckled beef cows. Suckled beef cows (n = 1101) at four locations were randomized to receive either 100 or 200 µg of gonadorelin acetate at initiation (D-8) of a 5-day CO-Synch + P4 protocol concurrently with insertion of an intravaginal progesterone (P4) device. On D-3 the P4 device was removed, two doses of prostaglandin F2α were administered concurrently and a patch was applied to evaluate expression of estrus. Artificial insemination was performed 72 h after P4 device removal (D0) simultaneously with the administration of 100 µg of gonadorelin acetate (GnRH-2). Increasing GnRH dose at initiation of a 5-day CO-Synch + P4 did not enhance ovulatory response (P = 0.57) to GnRH-1, expression of estrus (P = 0.79), nor pregnancies per AI (P/AI; P = 0.91). Both follicle size (quadratic) and circulating P4 (linear) affected (P < 0.01) ovulatory response to GnRH-1 independent of dose. Cows that had ovulation to GnRH-1 had smaller (P < 0.001) follicle size on D-3 and reduced (P = 0.05) expression of estrus compared to cows that did not have ovulation to GnRH-1, however, P/AI did not differ (P = 0.75). In conclusion, increasing the dose of GnRH-1 in the 5-day CO-Synch + P4 protocol did not enhance ovulatory response, expression of estrus, or P/AI in suckled beef cows.

Strategic re-use of intravaginal progesterone devices increases conception rate in primiparous Nellore cows

In the present study, we investigate the effect of the presence or absence of corpus luteum (CL) at the beginning of a fixed-time artificial insemination (FTAI) protocol and to evaluate the impact of one-time use of intravaginal progesterone device (P4 device) in cows with or without CL. A total of 776 primiparous Nellore cows were subjected to FTAI approximately 45 days postpartum. In Experiment 1, 476 cows were divided into two experimental groups: with (CL-present, n=113) or without (CL-absent, n=363) CL, after ultrasound evaluation. On day 0 (D0), all cows received a new P4 device (1.0 g) and 2.0 mg estradiol benzoate (EB). Eight days later (D8), the P4 devices were withdrawn, and prostaglandin (15 mg), estradiol cypionate (0.5 mg), and eCG (300 IU) were administered i.m. All cows were inseminated 48 h after P4 device withdrawal (D10). In Experiment 2, the cows (n= 300) received (at D0) P4 devices that were previously used once in other cows with (n=109) or without CL (n=191) and 2 mg of EB. The same protocol as that used in Experiment 1 was performed from D8 onwards. In Experiment 1, the overall conception rate after FTAI was 55% (262/476). No difference was found in the conception rate between CL-present and CL-absent cows (52.2 vs. 55.5%). In Experiment 2, the conception rate obtained with P4 devices previously used in cows with CL (58.7%) was greater (P&lt;0.05) than that obtained with P4 devices previously used in cows without CL (42.9%). Thus, this strategy resulted in a 15.8% increase in conception rate. In conclusion, the presence or absence of CL at the beginning of the FTAI protocol did not affect the conception rate in cows synchronized with the new P4 device, but the insertion of P4 devices previously used in cows with CL enhanced the conception rates in cows without CL.

Comparison of Estradiol Cypionate, Estradiol Benzoate and Gonadotropin-Releasing Hormone in Fixed-Time Artificial Insemination in Multiparous Murrah Buffaloes

The present study was aimed to evaluate the efficiency of estradiol cypionate, estradiol benzoate and gonadotropin-releasing hormone during fixed-time artificial insemination (FTAI) protocols in multiparous Murrah buffaloes. A total of 35 buffaloes were used between September and November 2021 and subjected to a synchronization protocol. On day 0, insertion of an intravaginal progesterone device (CIDR, 1.38 g) was made with intramuscular (i/m) injection of estradiol benzoate (EB, 2 mg); On day 9: CIDR removed with i/m injections of Dinoprost (12.5 mg) and eCG (400 IU), and then buffaloes were randomized into three treatment group: 1) EB 1 mg on day 10 (n=13). 2) estradiol cypionate (EC) 1 mg on day 9 (n=12), and 3) Buserelin acetate (GnRH) 0.0105 mg on day 10 (n=10). The estrus signs observed during the FTAI (56 h after CIDR withdrawal) and conception rate at 90 days after FTAI were recorded. The conception rates were 61.5, 58.3 and 60.0% for EB, EC and GnRH treatment groups, respectively. There was no significant difference between the treatment groups for conception rate and signs of estrus. Therefore, it was concluded that all three treatments can be efficiently used during estrus synchronization protocol with FTAI in multiparous Murrah buffaloes.

Comparison of the efficiency of progesterone, ketoprofen, or GnRH administration on the day of fixed-time transfer (FTET) of in vitro produced (IVP) embryos in suckled crossbred beef cows

ABSTRACT The objective is to treat cows receiving IVP embryos with injectable progesterone, ketoprofen, and gonadorelin on the day of FTET and to compare the reproductive efficiency of untreated cows with that of treated cows, using pregnancy per ET as the response variable. 32 oocyte donor cows were used and 392 embryo transfers were performed in multiparous cows. Recipient cows were synchronised with the protocol: on day zero (d0), an intravaginal progesterone device was inserted (1.0 g P4), and 2.0 mg estradiol benzoate (EB;im) was administered; on d8, the P4 device was removed, and 150 µg of cloprostenol was administered; on d9, 1.0 mg EB was administered; and on d17, embryo transfers were performed. On d17, recipient cows were randomly assigned to one of four groups: those treated with injectable progesterone (iP4G, 150 mg; n = 84), ketoprofen (KetoprofenG, 1000 mg; n = 104), gonadorelin (GonadorelinG, 100 µg; n = 80), or the control (untreated) group (NTG, n = 124). Pregnancy diagnosis was performed 35 days following embryo transfer, showing pregnancy per FTET of 42.8, 57.6, 55.0, and 43.5% for iP4G, KetoprofenG, GonadorelinG, and NTG, respectively. It is concluded that ketoprofen improves FTET pregnancy rates when compared to injectable progesterone and control group. Gonadorelin demonstrated comparable efficacy to ketoprofen.

Association between length of proestrus, follicular size, estrus behavior, and pregnancy rate in beef heifers subjected to fixed–time artificial insemination

This study evaluated the relationship between proestrus length and follicular size, estrous behavior, and pregnancy rate in Bos taurus beef heifers subjected to fixed–time artificial insemination (FTAI). A total of 911 heifers received a synchronization treatment protocol for FTAI (J–Synch) consisting of an intravaginal progesterone device for 6 d, estradiol benzoate at the time of device insertion cloprostenol sodium and eCG at device removal and GnRH at the time of FTAI. The presence or absence of a corpus luteum (CL) was determined by ultrasonography at device insertion and all heifers were tail painted at device removal for estrus detection at the time of FTAI. For the establishment of different periods of proestrus length (i.e., interval from device removal to FTAI), GnRH was administered i.m. at 48 h (n = 308), 60 h (n = 290) or 72 h (n = 313) after device removal. The diameter of the largest follicle at the time of GnRH administration was determined by ultrasonography, expression of estrous was determined by percentage of tail paint removal, and FTAI was performed at the time of GnRH administration in all heifers. The diameter of the largest follicle was greater when GnRH/FTAI was performed at 72 or 60 h (12.9 ± 0.2 mm and 12.8 ± 0.1 mm, respectively) than at 48 h (12.2 ± 0.1 mm, P < 0.05). The proportion of heifers in estrus tended to be greater when GnRH/FTAI was performed at 72 h (77.0%, 137/178) than at 48 h (68.2%, 122/179; P = 0.06), and intermediate at 60 h (71.4%, 120/168). Pregnancy rate tended to be greater in heifers with the longest (72 h: 70.0%, 219/313) than the shortest (48 h: 63.6%, 196/308; P < 0.1) proestrus length, while 60 h proestrus length was intermediate (63.1%, 183/290; P= NS). Pregnancy rate was affected by the presence of a CL at device insertion (71.3%, 352/494 in heifers with a CL, vs. 59.0%, 246/417 for those without a CL; P < 0.01). For those heifers bearing a CL, pregnancy rate was greater in heifers with a 72 h proestrus length (77.0%, 134/174) than with 48 or 60 h proestrus length (67.7%, 107/158 and 68.5%, 111/162; respectively; P < 0.05). In heifers without a CL, proestrus length did not affect pregnancy rate. In summary, extending proestrus length by delaying the interval from device removal to GnRH/FTAI from 48 to 72 h, was associated with a greater diameter of the preovulatory follicle, greater proportion of heifers expressing estrus at the time of FTAI, and greater pregnancy rate in cycling beef heifers.

124&#x2003;Reutilisation of intravaginal progesterone devices during fixed-time artificial insemination with sex-sorted semen in dairy heifers.

Reproduction, Fertility and Development is an international journal publishing original research , review and comment in the fields of reproduction and developmental biology in humans, domestic animals and wildlife

Progesterone release profile and follicular development in Nelore cows receiving intravaginal progesterone devices

This study aimed to evaluate the progesterone (P4) release profile provided by four commercially available intravaginal P4 devices, as well as the effect of circulating P4 concentrations exclusively from these devices on the development of the dominant follicle (DF) in Nelore (Bos indicus) cows. Therefore, non-lactating multiparous Nelore cows were enrolled in an experimental design, over three replicates, starting on Day −9 with the insertion of a reused P4 device (2 g – original P4 load) for 7 d, followed by two treatments of cloprostenol sodium (PGF; 0.482 mg), 24 h apart, on Days −3 and −2. Just before device removal, on Day −2, a norgestomet ear implant was inserted and, 2 d later (Day 0), at the time of norgestomet withdrawal, cows were randomly assigned to receive one of the intravaginal devices: Primer (0.5 g); Prociclar (0.75 g); Sincrogest (1 g); or CIDR (1.9 g), and 2 mg of estradiol benzoate (EB) im. Blood samples were collected immediately before P4 device insertion, 12 h later and daily over 15 d (1 d after P4 device removal). Ultrasound examinations were performed on Days 0, 7, 8, 9, 10, 12, and 14 to evaluate ovarian dynamics. Results are presented as mean ± SEM and differences were considered when P ≤ 0.05. Overall, the devices resulted in distinct circulating P4 concentrations over 10 d, varying according to their initial P4 load and P4 impregnated surface area. Primer provided the lowest circulating P4 concentrations over time, whereas, CIDR had the greatest concentration. Sincrogest and Prociclar were similar, producing intermediary circulating P4. There was no effect of treatment on the DF diameter on any specific day, nor on follicular growth rate from Day 7–10. However, the Primer device resulted in a greater mean DF diameter over time. Additionally, greater circulating P4 concentrations, mainly during the first 3 d of device insertion, were associated with smaller DF diameters regardless of the treatment. In conclusion, results from this study provided a better understanding of the P4 profile of intravaginal P4 devices, as well as, their effect on DF development in Bos indicus cows. These data contribute to optimize the use of P4 devices in the reproductive management of beef cattle.

Estradiol cypionate treatment in suckling/weaning and estrous cycling/anestrous beef cows subjected to fixed-time artificial insemination

This study was conducted to evaluate the interaction between dose of estradiol cypionate (ECP) and ovarian status in beef cows on which different weaning/suckling regimens were imposed before fixed-time artificial insemination (FTAI). A total of 8070 estrous cycling and anestrous cows were subjected to three experiments, when calves were weaned early (Experiment 1), anti-suckling nose plates were applied for 9 or 10 days (Experiment 2), or there was continued suckling (Experiment 3). The cows were administered an estradiol/progesterone–based treatment regimen for FTAI and were treated with 0.5 or 1.0 mg of ECP im at the time of progesterone intravaginal device removal. Artificial insemination was performed from 46 to 56 h after the time of ECP treatment. Pregnancy per artificial insemination (P/AI) was affected by dose of ECP differentially in early-weaned and suckled cows. Whereas P/AI percentage was greater in early-weaned cows treated with 0.5 than 1.0 mg ECP (P < 0.05), P/AI percentage was greater for suckled cows treated with 1.0 than 0.5 mg ECP (P < 0.05). Although there were greater P/AI percentages in estrous cycling than anestrous cows (P < 0.05) when there was nose plate weaning and continuation of suckling, there was no difference between estrous cycling and anestrous cows (P = NS) when there was early weaning. Overall results indicate ECP administration affects fertility in a dose-dependent manner, suggesting an interaction between suckling and estrous cycling effects. As more critical the condition was (i.e., suckling anestrous cows), larger dose of estradiol was required.

Intravaginal progesterone device (1.9g) and estradiol benzoate for follicular control in the mare during spring and summer

ABSTRACT The objective of this study was to evaluate follicular growth and ovulatory rates in mares treated with an intravaginal progesterone device (P4) during the 10-day period, associated with the use of estradiol benzoate (EB). The results were compared during the transition period (ET) in the spring and the breeding season in the summer (ER). The variables were submitted to ANOVA (Tukey's test), considering P&lt;0.05. No ovulation occurred during the permanence of the P4 implant in both experimental periods. The ovulatory rate in the ER was 100% (n = 8) and in the ET 62.5% (n = 5; P = 0.0547). Significant differences were observed (&lt;0.001), in both periods, comparing follicular growth rates during the permanence of P4 device (ER: 1.33 ± 0.89mm/d; ET: 1.00 ± 0.81mm/d) to the period without P4 (ER: 3.63 ± 1.33 mm/d; ET: 3.31 ± 1.66 mm/d). The present study demonstrated applicability and efficiency of a hormonal protocol using P4 intravaginal device and EB for follicular control in mares, both during ET and ER.

Progesterone release profile and follicular development in Holstein cows receiving intravaginal progesterone devices

The aim of this study was to evaluate the progesterone (P4) release profile provided by eight commercial intravaginal P4 devices, as well as the effect of circulating P4 concentrations produced exclusively by these devices on the development of the dominant follicle (DF) in non-lactating multiparous Holstein cows. All cows were submitted to the same experimental design starting with the insertion of a reused P4 device (2 g – original P4 load) for 7 d, followed by two treatments of cloprostenol sodium (PGF; 0.482 mg), 24 h apart, 6 and 7 d after device insertion. Just before device removal, a Norgestomet ear implant was inserted and, 2 d later (Day 0), simultaneously to Norgestomet withdrawal, cows received one of the tested intravaginal devices and 2 mg of estradiol benzoate (EB) im. In Exp.1 (n = 22; three replicates), cows were randomized to receive: CIDR (1.38 g); PRID-Delta (1.55 g); Prociclar (0.75 g); or Repro sync (2 g). In Exp. 2 (n = 29; four replicates), cows were randomized to receive: Cue-Mate (1.56 g); DIB 0.5 (0.5 g); DIB (1 g); PRID-Delta (1.55 g); or Sincrogest (1 g). Blood samples were collected before P4 device insertion (Day 0), 12 h later and daily over 15 d (1 d after P4 device removal). Ultrasound examinations were performed to evaluate growth of the DF on Days 0, 7, 8, 9, and 10. Results are presented as mean ± SEM and differences were considered when P ≤ 0.05. Overall, the circulating P4 profile and mean circulating P4 over 10 d differed among treatments. However, no effects were observed on the DF diameter and follicular growth rate from Day 7–10 after P4 device insertion. In Exp. 2, devices that provided higher circulating P4 concentrations were associated to a slower DF growth during the treatment period. Finally, this study provided a better understanding of the P4 release profile produced by intravaginal P4 devices as well as their effect on circulating P4 concentrations and DF development in non-lactating Holstein cows.

Comparação entre dispositivos intravaginais de progesterona de primeiro e quarto uso para reprodução em bovinos

The intravaginal progesterone device is the most expensive of the estrus synchronization protocol, which may make it impossible for the producer to access this biotechnology. The aim of the present study was to compare the pregnancy rate between implants with new devices and fourth use in two farms in Amazonas. Data were acquired through the MultBovinos® program. The results show a pregnancy rate of 56.06% for new devices and 67.14% for fourth use on Farm 01 and 67.09% for new devices and 70.97% for fourth use on Farm 02. Therefore, the reuse of 1.9 g progesterone intravaginal implants obtained better pregnancy rate results when compared to the first use.

Reproductive strategies for dairy heifers based on 5d-Cosynch with or without an intravaginal progesterone device and observed estrus

The objective of this randomized, controlled study was to evaluate the reproductive and economic performance of dairy Holstein heifers managed for first to third artificial inseminations (AIs) with or without an intravaginal progesterone device (IPD) under different temperature-humidity indexes (THI) and combined with AI after observed estrus. A total of 503 heifers from one rearing commercial farm were randomly assigned for first AI to the 5d Co-synch 72 h protocol (5dCO; n=261) or to the 5d Co-synch protocol plus IPD (5dCOP4; n=242). In a subset of heifers (n = 193) we determined progesterone (p4) and performed an ovarian ultrasound scanner on Days 0, 5, 8 and 15. Animals were considered to be synchronized on Day 5 if p4 > 1 ng/mL and a corpus luteum present; synchronized on Day 8 if p4 < 1 ng/mL, luteolysis and a follicle > 8 mm diameter was observed; and synchronized on Day 15 if p4 > 1 ng/mL and ovulation occurred, defined as the presence of a CL in the ovary where a follicle had been detected on Day 8. Pregnancy diagnosis was performed by ultrasound scanner on Days 28-35 after AI. The diagnosis confirmation was done by ultrasound on Days 50-56 and again on Days 100-113 after AI. Non-pregnant heifers (n=205) were resynchronized with the same protocol for second fixed-time AI (FTAI) and 104 for third FTAI. Pregnancy per AI (P/AI) and pregnancy loss after each AI were calculated. Reproductive costs were calculated at the individual level, based on costs for pregnancy and cost for the open days. Estrus observation was performed by visual inspection for 20 min periods, twice a day and heifers observed in estrus inseminated (OEAI). Observed in estrus inseminated heifers were 10.5% at first, 26.8% at second and 24.0% at third AI (P >0.05). The global P/AI after first AI was 58.6%; the P/AI after FTAI, 58.0%; and the P/AI after first OEAIs, 64.2%. Pregnancy per AI values were better in the IPD group [55.2% for 5dCO vs. 62.4% for 5dCOP4; odds ratio (OR) 0.35, 95% confidence interval (CI) 0.18-0.70; P=0.003], and a significant effect of the temperature humidity index (THI) on P/AI was observed (P = 0.03). The protocol 5dCOP4 led to a significantly better synchronization rate (85.7% vs. 40.0% for 5dCO; P = 0.01) and a numerically higher P/AI (74.5% vs. 49.0% for 5dCO; P = 0.24) when THI values were ≥ 70. During the cold season, there were no differences between the experimental groups for the synchronization rate (P = 0.9) nor for the P/AI (P = 0.6). The P/AI was 52.2% after the second AI and 60.6% after the third AI. Inseminations per pregnancy and open days did not differ significantly across experimental groups. However, reproduction costs per heifer were 130.8 ± 116.1 and 152.3 ± 129.5€ for 5dCO and 5dCOP4 groups, respectively, for the whole study (P = 0.051) and the average cost per AI was 58.23 ± 27.9 € for 5dCO and 76.3 ± 36.2 € for 5dCOP4 (P < 0.0001). During the cold season, protocols were associated with similar costs to the whole study, but they differed notably during the hot season (194.3 ± 137.6 vs. 177.3 ± 134.2 for 5dCO and 5dCOP4, respectively; P=0.49), reflecting the better reproductive performance with an IPD during the summer (P = 0.003). Advisors and farmers need to consider farm conditions and characteristics (herd management, staff training, and seasonality, among others) to achieve the best economic and reproductive performance in the dairy herds, when implementing hormonal synchronization protocols. Thus, cost-effectiveness depends on seasonality when implementing reproductive strategies with 5 d Co-synch 72h and combined OEAI at a rearing farm. With high THI-values, the inclusion of IPD in hormonal protocols in heifers is recommended, while it is not required during the cool season.