1115 The 9-d CIDR-PG protocol: Incorporation of prostaglandin pretreatment into a long-term, CIDR-based estrus synchronization protocol improves timed AI pregnancy rates in postpartum suckled beef cows

The aim of this study was to investigate estrus synchronization in prepubertal and pubertal heifers (crossbred ½ Nelore x Red Angus - commercial herd) submitted to a long-term progesterone-based protocol for timed artificial insemination (TAI), as well as overall pregnancy rates. Four hundred forty-seven heifers underwent ultrasound examination of the ovaries and were assigned to one of 3 groups: (1) prepubertal heifers (PPNS; n = 114) with ovarian follicles <8 mm in diameter and no corpus luteum (CL) that were submitted to natural service (NS) by bulls for 10 days; (2) prepubertal heifers (PPTAI; n = 124) with follicles <8 mm in diameter and no CL that underwent estrus synchronization with injection of 4.0 mg estradiol benzoate (EB) and insertion of a controlled-release intravaginal progesterone (P4) device containing 0.558 g P4 on d 0, followed by P4 device removal and injection of 150 mg prostaglandin F2α and 0.6 mg estradiol cypionate (ECP) on d 8, and TAI on d 10; and (3) pubertal heifers (PTAI; n = 209) with follicles >8 mm in diameter and/or a CL that underwent the same protocol as PPTAI heifers. Overall pregnancy rate was determined by transrectal ultrasonography on d 45 after NS or TAI. Data were analyzed using the FREQ procedure of SAS (SAS Inst. Inc., Cary, NC). Pregnancy rates were as follows: 20.1% in PPNS, 37.0% in PPTAI, and 48.5% in PTAI (P < 0.05). In conclusion, TAI after estrus synchronization with a hormonal protocol using EB and ECP in prepubertal and pubertal heifers resulted in higher pregnancy rates than prepubertal heifers exposed to natural service, and exposure of prepubertal heifers to a long-term progesterone-based protocol effectively synchronized estrus.

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PSXIII-11 Altering length of the presynchronization period in a long-term progestin-based estrus synchronization protocol for timed artificial insemination of beef heifers

Journal of Animal Science ◽

10.1093/jas/skz258.747 ◽

2019 ◽

Vol 97 (Supplement_3) ◽

pp. 375-376

Author(s):

Emma R Knickmeyer ◽

Jordan M Thomas ◽

James William C Locke ◽

Rachael C Bonacker ◽

Lauren Ciernia ◽

...

Keyword(s):

Artificial Insemination ◽

Reproductive Tract ◽

Prostaglandin F2α ◽

Estrus Synchronization ◽

Dominant Follicle ◽

Estrus Detection ◽

Timed Artificial Insemination ◽

Split Time ◽

Synchronization Protocol

Abstract An experiment was designed to evaluate the effect of extending the presynchronization period in a progestin-based estrus synchronization protocol. Heifers were assigned to an 18 d or 14 d CIDR® treatment (1.38 g progesterone), with prostaglandin F2α (PG; 250 mg im) administered 16 d after CIDR® removal (Day 34). Heifers at two locations (location one, n = 193; location two, n = 649) were assigned to treatment based on reproductive tract score (RTS; Scale 1–5) and weight. Estrus detection aids (Estrotect®) were applied at PG and split-time artificial insemination (STAI) was performed based on estrus expression at 66 h. Heifers that expressed estrus at 66 h were inseminated and heifers that did not express estrus were inseminated at 90 h. Only heifers that failed to express estrus by 90 h received gonadotropin-releasing hormone (GnRH; 100 µg im) at AI. At location one, blood samples were collected at PG and AI (66 h or 90 h) from all heifers to determine E2 concentrations, and transrectal ovarian ultrasound was performed to detail ovarian structures on a subset of heifers (n = 73) at both time points. The proportion of heifers expressing estrus by 66 h (60%) or in total by 90 h (84%) after PG did not differ between treatments. Pregnancy rate to STAI did not differ between treatments (P = 0.3; 52%, 14 d CIDR®-PG; 50%, 18 d CIDR®-PG), or at the end of the 60 d breeding season (P = 0.2). There were no differences between treatments in mean diameter of the dominant follicle at PG (P = 0.6) or STAI (P = 0.3), nor were any differences observed between treatments in E2 concentrations at PG (P = 0.8) or STAI (P = 0.6). These data suggest that CIDR® treatment can be extended from 14 to 18 d, providing flexibility in scheduling without compromising reproductive outcomes.

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PSXIII-12 Evaluation of split-time artificial insemination following administration of the 7-d CO-Synch + CIDR® estrus synchronization protocol in beef heifers

Journal of Animal Science ◽

10.1093/jas/skz258.745 ◽

2019 ◽

Vol 97 (Supplement_3) ◽

pp. 374-374

Author(s):

Emma R Knickmeyer ◽

Jordan M Thomas ◽

James William C Locke ◽

Rachael C Bonacker ◽

Mark R Ellersieck ◽

...

Keyword(s):

Artificial Insemination ◽

Reproductive Tract ◽

Fixed Time ◽

Pregnancy Rates ◽

Estrus Synchronization ◽

Beef Heifers ◽

Estrus Detection ◽

Delayed Time ◽

Split Time ◽

Synchronization Protocol

Abstract Estrous response and pregnancy rates resulting from fixed-time (FTAI) or split-time (STAI) artificial insemination were compared among heifers following treatment with the 7-d CO-Synch + CIDR® (controlled internal drug release;1.38g progesterone) protocol. Heifers (n = 456) were assigned to balanced treatments based on weight and reproductive tract score (RTS; Scale 1–5). Gonadotropin-releasing hormone (GnRH; 100 µg gonadorelin acetate) was administered coincident with CIDR® insertion. Progesterone inserts were removed after 7 d, and PG (250 mg im cloprostenol sodium) was administered at CIDR® removal. Estrus detection aids (Estrotect®) were applied at the time PG was administered. Estrous status was recorded at FTAI or STAI, and estrus was defined as removal of ≥ 50% of the grey coating from the Estrotect® patch. Heifers assigned to the FTAI treatment received GnRH and were artificially inseminated 54 h after PG administration. In the STAI treatment, only heifers that expressed estrus prior to 54 h were artificially inseminated at that time. For heifers failing to express estrus, AI was postponed 24 h and only those heifers that failed to exhibit estrus by the delayed time (78 h) received GnRH concurrent with AI. Estrous response prior to the standard time of FTAI did not differ between treatments (P = 0.3). Total estrous response was increased (P < 0.001) among heifers assigned to STAI (74%, STAI; 47%, FTAI); however, pregnancy rates resulting from AI were similar between treatments (48%, STAI; 46%, FTAI; P = 0.4), as were pregnancy rates at the end of a 60 d breeding season (P = 0.6). In summary, STAI resulted in a greater estrous response following treatment with the 7-d CO-Synch + CIDR® protocol; however, this did not result in an increase in pregnancy rate compared to heifers that received FTAI.

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Melengestrol acetate, estradiol-17β and GnRH for synchronization of estrus and ovulation in beef cows

Canadian Journal of Animal Science ◽

10.4141/a98-089 ◽

1999 ◽

Vol 79 (1) ◽

pp. 39-43 ◽

Cited By ~ 6

Author(s):

J. Thundathil ◽

J. P. Kastelic ◽

W. O. Olson ◽

R. B. Cook ◽

R. J. Mapletoft

Keyword(s):

Key Words ◽

Pregnancy Rate ◽

Beef Cows ◽

Pregnancy Rates ◽

Conception Rate ◽

Estrus Synchronization ◽

Short Term ◽

Melengestrol Acetate ◽

Conception Rates ◽

Estradiol 17Β

Three experiments were conducted with suckled crossbred beef cows to determine the efficacy of various short-term regimens for synchronizing estrus or ovulation and to determine whether feeding melengestrol acetate (MGA) after timed AI will increase pregnancy rate. In exp. 1, all cows (n = 141) were given 0.5 mg MGA head−1 d−1 for 7 d (days 1 to 7), 1 or 5 mg E17β (and 100 mg progesterone) or 100 µg GnRH on day 1, and 500 µg cloprostenol on day 7. There were no significant differences among groups for estrous or synchronized conception rates (average, 84.4 and 52.1%, respectively). With an identical protocol in exp. 2 (78 cows), by day 11, cows given 5 mg E17β had the highest estrous and synchronized pregnancy rates (65.4 and 42.3%), compared to 1 mg E17β (46.2 and 15.4%) and GnRH (34.6 and 11.5%). Cows not detected in estrus were timed-inseminated and given 100 µg GnRH, 100 h after cloprostenol. There were no significant differences among groups for synchronized conception rate to timed AI (65.0%) or synchronized pregnancy rate to all inseminations (56.4%). Overall, 5 mg E17β gave the most consistent results. In exp. 3, 84 cows were given 100 µg GnRH on days 1 and 9, 500 µg cloprostenol on day 7, and were timed-inseminated on day 10. Half were fed MGA (0.5 mg head−1 d−1) on days 16 to 22, but the pregnancy rate was not different from that in the remaining cows (55.0 versus 47.8%, P > 0.5). Key words: Ovary, follicles, estrus synchronization, beef cows

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PSXIII-14 The impact of estrus intensity on variables associated with fertility in Bos taurus-influenced beef cows

Journal of Animal Science ◽

10.1093/jas/skz258.724 ◽

2019 ◽

Vol 97 (Supplement_3) ◽

pp. 362-363

Author(s):

Reinaldo F Cooke ◽

Nicola Oosthuizen ◽

Kelsey Schubach ◽

Alice Brandão ◽

Ramiro Oliveira Filho ◽

...

Keyword(s):

Physical Activity ◽

Bos Taurus ◽

Fixed Time ◽

Beef Cows ◽

Estrus Synchronization ◽

Estrus Detection ◽

Follicle Size ◽

The Impact ◽

Ovarian Dynamics ◽

Synchronization Protocol

Abstract To evaluate the impact of estrus expression and intensity on parameters associated with reproductive performance, 219 lactating, multiparous Bos taurus-influenced beef cows were enrolled in this study. Cows were exposed to an estrus synchronization protocol, where they received a 100-µg injection of GnRH and a CIDR insert on d -10, a 25-mg injection of PGF2a at CIDR removal on d -3, and an injection of GnRH 60–66 h following CIDR removal at fixed-time AI (TAI; d 0). Cows were fitted with a pedometer behind their right shoulder on d -10, and an estrus detection patch was applied to their tail-head on d -3. Estrus expression was defined as removal of > 50% of the rub-off coating from the patch on d 0. Net physical activity during estrus was calculated by subtracting daily activity during the non-estrus period (d -10 to -3) from activity during the expected estrus period (d -3 to 0). Cows were classified into 3 groups: cows that did not express estrus (NOESTR; n = 119), cows that expressed estrus with net physical activity greater than the median (HIESTR; n = 50), and the remaining cows (LWESTR; n = 50). Ultrasonography was performed on d -3, 0, and 7 to determine the presence and size of ovarian structures. Pregnancy diagnosis was performed 29 d after TAI. Net physical activity was greater in HIESTR compared to both LWESTR and NOESTR (P < 0.01). Dominant follicle size was greater in HIESTR compared to both LWESTR and NOESTR (P < 0.01). Furthermore, HIESTR had greater corpus luteum volume on d 7 than LWESTR and NOESTR (P < 0.01). Pregnancy rates to AI (PR/AI) were greater in HIESTR and LWESTR compared to NOESTR (P < 0.01). In conclusion, cows that expressed estrus at a greater intensity had improved ovarian dynamics. Additionally, cows that exhibited estrus had greater PR/AI compared to non-estrual cows.

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Effect of different protocols for estrus synchronization on reproductive performance of Santa Inês ewes under Amazon environmental conditions

Acta Scientiarum Animal Sciences ◽

10.4025/actascianimsci.v43i1.48954 ◽

2020 ◽

Vol 43 ◽

pp. e48954

Author(s):

Regina Oliveira da Silva ◽

Roseane Pinto Martins de Oliveira ◽

André Ferreira Silva ◽

Franklyn Ferreira de Oliveira ◽

João Paulo Ferreira Rufino ◽

...

Keyword(s):

Experimental Design ◽

Pregnancy Rate ◽

Reproductive Performance ◽

Environmental Conditions ◽

Pregnancy Rates ◽

Estrus Synchronization ◽

Test Results ◽

Short Term ◽

Santa Inês

The objective of this study was to evaluate the effect of different hormonal protocols on the reproductive performance of Santa Inês ewes in Amazon environmental conditions. Twenty-two Santa Inês ewes between 3 and 4 years-old were distributed in a randomized block experimental design, where the treatments consisted of two protocols for estrus synchronization (short and long) with eleven animals each. Data on the occurrence of estrus were described for each protocol. Data of estrus, pregnancy, and prolificity were firstly subjected to ANOVA and a subsequent Tukey’s test. Results were considered significant at p ≤ 0.05. The short-term protocol presented an interesting successful rate, where above 70% ewes tested had estrus. The long-term protocol also achieved a high successful rate, where above 80% ewes tested had estrus. However, comparing the protocols, the long-term protocol presented better results of positive estrus and pregnancy rates in ewes. Thus, it can be concluded that both protocols presented satisfactory results regarding estrus manifestation, and prolificity (lambs produced per ewe). However, under Amazon environmental conditions, the long-term protocol presented better results regarding positive manifestation of estrus and pregnancy rate.

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24 EFFECT OF GnRH ON FIXED-TIMED ARTIFICIAL INSEMINATION PREGNANCY RATES OF WHITE-TAILED DEER

Reproduction Fertility and Development ◽

10.1071/rdv22n1ab24 ◽

2010 ◽

Vol 22 (1) ◽

pp. 170

Author(s):

J. Lambe ◽

W. Forbes ◽

B. M. Olcott ◽

D. E. Sanders ◽

R. A. Godke ◽

...

Keyword(s):

Artificial Insemination ◽

Pregnancy Rates ◽

Transrectal Ultrasonography ◽

Estrus Synchronization ◽

Control Groups ◽

Motile Cells ◽

Timed Artificial Insemination ◽

And Control ◽

Uterine Body ◽

Synchronization Protocol

During the fall 2008 breeding season in Louisiana, 2 synchronization protocols for fixed-timed artificial insemination (FTAI) in White-tailed deer were assessed. The objective was to determine if GnRH at FTAI improved pregnancy rates in White-tailed deer. White-tailed does (n = 35) with a mean body weight of 65.8 kg (range: 54.0 to 79.8 kg) and average age of 5.9 years (range: 1.5 to 9.5 years) were stratified by weight, age, and last fawning date into 2 groups. Treatment and control synchronization protocols were randomly assigned to each group. Does were synchronized with a CIDR-G device for 14 d and were then subjected to either FTAI 60 hpost-CIDR removal (control, n = 17) or 100 μg (i.m) injection of GnRH at FTAI 60 h post-CIDR removal (treated, n = 18). At insemination (AI), insemination pipette placement score (IP; 0 = at cervical os to 3 = within uterine body), mucous scores (clear/cloudy, viscous/nonviscous, or no secretions), vulva assessments (hyperemic/nonhyperemic and swollen/not swollen), and sperm progressive motility were recorded. Does were inseminated with frozen-thawed sperm (5 × 107 progressively motile cells pre-freeze) from 2 fertile bucks stratified across each treatment group. Starting 28 d following AI, intact bucks (ITB) were introduced into both groups for natural mating. Pregnancy was determined via transrectal ultrasonography 73 or 80 d postinsemination. Does, confirmed pregnant via ultrasonography, had fawns within the reported gestation range of 187 to 222 days. Placentomes were visualized and measured in AI pregnancies (range: 32.7 to 56.2 mm in length), whereas pregnancies derived from ITB presented no identifiable placentomes. However, crown-rump measurements were obtainable from ITB pregnancies (range: 13.4 to 21.7 mm). Five does were not included in the final analyses as they were either lost to predators or removed because of illness. IP (1.4 ± 0.24 v. 1.3 ± 0.30; P = 0.671), mucous classifications (3.0 ± 0.35 v. 2.5 ± 0.39; P = 0.311), vulva assessments (2.1 ± 0.29, 1.7 ± 0.23; P = 0.223), and sperm motility (1.6 ± 0.16, 1.7 ± 0.22; P = 0.829) were not different for pregnant and nonpregnant AI does, respectively. Treatment did not affect AI pregnancy rates (53 v. 27%) or fecundity rates (1.6 v. 1.3 offspring/doe) for the GnRH treated and control groups, respectively. Addition of GnRH to a 14-day estrus synchronization protocol did not result in significantly higher pregnancy rates compared with controls. More studies are needed to determine the effect of GnRH on White-tailed pregnancies following FTAI protocols. We have demonstrated that differentiating pregnancies derived from AI and ITB could be accomplished by utilizing transrectal ultrasonography as early as 73 d postinsemination in White-tailed does.

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