Fixed-time artificial insemination in replacement beef heifers after estrus synchronization with human chorionic gonadotropin or gonadotropin-releasing hormone1

The aim of this study was to investigate the effects of hormonal support on the pregnancy rate in repeat breeder cows. Prostaglandin F2α + Ovsynch oestrus synchronization protocol was applied to the cows. Following the fixed time insemination (day 0), the cows were divided into 4 groups. In Group 1 (n = 42), progesterone releasing intravaginal device (PRID) was placed vaginally at 84 h and removed on the 9th day after the artificial insemination. In Group 2 (n = 40), the cows were administered human chorionic gonadotropin (hCG) on the 7th day. Group 3 (n = 45) was applied a combination of progesterone and hCG. Group 4 (n = 42) was not given any treatment. Blood samples were collected from all cows 4 times on days 3.5, 7, 12, and 18 to evaluate progesterone concentrations. The pregnancy rates were 40.47%, 37.50%, 44.44%, and 30.95% in Group 1, 2, 3, and 4, respectively (P > 0.05). In addition, in cows with progesterone concentrations <2 ng/ml on day 3.5, the pregnancy rates were found to be lower than in the cows with progesterone concentrations >2 ng/ml in Group 4 (P < 0.05). Progesterone supplementation in cows with progesterone concentrations < 2 ng/ml appeared to increase pregnancy rates (P < 0.05) in Groups 1 and 3. As a result, post-insemination hormonal applications in the repeat breeder cows did not increase the pregnancy rate. However, it was concluded that determination of progesterone concentrations on day 3.5 following artificial insemination and then hormonal support in the cows with low concentrations would increased the pregnancy rate.

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Effects of presynchronization and eCG on pregnancy rates to GnRH-based, fixed-time artificial insemination in beef heifers

Canadian Journal of Animal Science ◽

10.4141/cjas09058 ◽

2010 ◽

Vol 90 (1) ◽

pp. 23-34 ◽

Cited By ~ 5

Author(s):

J A Small ◽

M G Colazo ◽

J P Kastelic ◽

N E Erickson ◽

R J Mapletoft

Keyword(s):

Chorionic Gonadotropin ◽

Artificial Insemination ◽

Follicular Development ◽

Fixed Time ◽

Pregnancy Rates ◽

Preovulatory Follicle ◽

Beef Heifers ◽

Plasma Progesterone ◽

Follicle Diameter ◽

Equine Chorionic Gonadotropin

Three experiments were conducted to determine the effects of presynchronization and treatment with equine chorionic gonadotropin (eCG) on corpus luteum (CL) and ovarian follicular development, plasma progesterone concentrations, and pregnancy rates in beef heifers subjected to a gonadotropin releasing hormone (GnRH)-based, fixed-timed AI (TAI) protocol. All heifers were given GnRH on day 0, prostaglandin F2α (PGF) on day 7, and a second GnRH on day 9 concurrent with TAI (54 h after PGF). In exp. 1 (N = 148), presynchronization with PGF (days -22 and -11) decreased the percentage of heifers with non-luteal plasma progesterone concentrations on day 0 (5.4 vs 29.7%) and day 7 (0 vs 11.6%; P < 0.05), but not on day 9 (74.3 vs. 66.2%; P > 0.20), and reduced the number of heifers in estrus and bred before TAI (P < 0.05). Although presynchronization reduced preovulatory follicle diameter (12.9 ± 0.3 vs. 14.9 ± 0.3 mm; mean ± SEM; P < 0.01), it did not affect TAI pregnancy rates (36.5 vs. 29.7%; P > 0.20). In exp. 2, heifers (N = 128) were presynchronized with melengestrol acetate (MGA) (days -27 to -12), and received a controlled internal drug release (CIDR) on day 0; on day 7, half were given 300 IU of eCG at CIDR removal. Treatment with eCG tended to increase preovulatory follicle diameter in heifers that did not ovulate to GnRH on day 0 (P = 0.06), but did not affect the percentage of heifers with non-luteal plasma progesterone concentrations on day 9 (57.8 vs. 57.8%) or TAI pregnancy rates (48.4 vs. 53.1%; P > 0.20). Experiment 3 was a 2 × 2 factorial arrangement of presynchronization (PGF concurrent with a CIDR on day -7) and eCG treatments (on day 7) applied to heifers in three herds (A, N = 150, B, N = 260 and C, N = 40). All heifers had a once-used CIDR from days 0 to 7. Presynchronization increased the percentage of heifers (Herd A) with low-luteal plasma progesterone concentrations on day 0 (70.7 vs. 22.7%) and day 7 (90.7 vs. 53.3%; P < 0.01), but did not affect the percentage of heifers with non-luteal concentrations of progesterone on day 9 (97.3 vs. 93.3%; P > 0.20). Combined for all herds, presynchronization reduced the prevalence of a CL on day 0 (23.5 vs. 73.7%; P < 0.01), and increased the prevalence of follicles ≥ 10 mm on day 7 (96.8 vs. 86.7%; P < 0.01); however, TAI pregnancy rates (195/439 = 44.4%) were not improved by either presynchronization or eCG treatment (P > 0.20).Key words: Presynchronization, equine chorionic gonadotropin, GnRH, fixed-time artificial insemination, progesterone

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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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510 Impact of estrus synchronization and fixed-time artificial insemination on calving distribution in Bos indicus influenced beef heifers

Journal of Animal Science ◽

10.2527/asasann.2017.510 ◽

2017 ◽

Vol 95 (suppl_4) ◽

pp. 249-249

Author(s):

N. Oosthuizen ◽

P. L. P. Fontes ◽

C. D. Sanford ◽

F. M. Ciriaco ◽

D. D. Henry ◽

...

Keyword(s):

Artificial Insemination ◽

Bos Indicus ◽

Fixed Time ◽

Estrus Synchronization ◽

Beef Heifers

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Estrus synchronization and fixed-time artificial insemination alter calving distribution in Bos indicus influenced beef heifers

Theriogenology ◽

10.1016/j.theriogenology.2017.10.028 ◽

2018 ◽

Vol 106 ◽

pp. 210-213 ◽

Cited By ~ 2

Author(s):

N. Oosthuizen ◽

P.L.P. Fontes ◽

C.D. Sanford ◽

F.M. Ciriaco ◽

D.D. Henry ◽

...

Keyword(s):

Artificial Insemination ◽

Bos Indicus ◽

Fixed Time ◽

Estrus Synchronization ◽

Beef Heifers

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PSI-27 Effect of antral follicle count on time intervals to estrus and ovulation in crossbred beef heifers

Journal of Animal Science ◽

10.1093/jas/skaa278.823 ◽

2020 ◽

Vol 98 (Supplement_4) ◽

pp. 472-472

Author(s):

Maria K Chavez ◽

Shelby L Rosasco ◽

Matthew C Herrington ◽

Joslyn K Beard ◽

Adam F Summers

Keyword(s):

Artificial Insemination ◽

Reproductive Function ◽

Antral Follicle ◽

Fixed Time ◽

Antral Follicle Count ◽

Prediction Tool ◽

Estrus Synchronization ◽

Beef Heifers ◽

Time Intervals ◽

Antral Follicles

Abstract While genetics are an unreliable indicator of fertility, antral follicle count (AFC) has recently been recognized as a useful fertility prediction tool in heifers. The aim of this study was to determine if AFC exerts an effect on response to synchronization, time to estrus (TTE), and/or time to ovulation (TTO). Twenty-five crossbred heifers were classified by AFC, either high (> 25 antral follicles), moderate (16–24 antral follicles), or low (< 15 follicles) and utilized in two experiments. In experiment 1, heifers were subjected to the Select Synch + CIDR fixed time artificial insemination (FTAI) protocol. After synchronization, estrus activity was monitored every 3 h until standing estrus was observed. Heifers were examined at 12 and 18 h after observation of standing estrus and every 3 h thereafter to monitor ovulation. In experiment 1, the proportion of heifers that responded to the protocol was not significant (P = 0.71) among classification groups. Time to estrus and time to ovulation were similar between groups (P > 0.90). In experiment 2, heifers were placed with bulls for 60 d and were monitored for signs of estrus every 3 h. Results of experiment 2 indicated that response to estrus synchronization was similar across groups (P = 0.46). Time to estrus was greater (P = 0.04) in the high AFC group than in the low or moderate AFC groups. This may be attributed to lower concentrations of circulating gonadotropins in high AFC heifers, resulting in decreased intrafollicular estradiol. Differences in TTE results between experiment 1 and experiment 2 may be explained by increased reproductive function as heifers continued to mature during the study. These results suggest that differences in TTE may be related to AFC. Additional research is needed to corroborate these results and inform the creation of differing FTAI protocols based on AFC.

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Administration of human chorionic gonadotropin 7 days after fixed-time artificial insemination of suckled beef cows1

Journal of Animal Science ◽

10.2527/jas.2009-2596 ◽

2010 ◽

Vol 88 (7) ◽

pp. 2337-2345 ◽

Cited By ~ 8

Author(s):

C. R. Dahlen ◽

S. L. Bird ◽

C. A. Martel ◽

KC Olson ◽

J. S. Stevenson ◽

...

Keyword(s):

Chorionic Gonadotropin ◽

Human Chorionic Gonadotropin ◽

Artificial Insemination ◽

Fixed Time

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Effects on Synchronization and Reproductive Efficiency of Delaying the Removal of the Intravaginal Progesterone Device by 24 h in the 5d Co-synch Protocol in Heifers

Animals ◽

10.3390/ani11030849 ◽

2021 ◽

Vol 11 (3) ◽

pp. 849

Author(s):

Aitor Fernandez-Novo ◽

Sergio Santos-Lopez ◽

Jose Luis Pesantez-Pacheco ◽

Natividad Pérez-Villalobos ◽

Ana Heras-Molina ◽

...

Keyword(s):

Animal Welfare ◽

Reproductive Performance ◽

Artificial Insemination ◽

Fixed Time ◽

Reproductive Efficiency ◽

Beef Heifers ◽

Animal Management ◽

Commercial Farms ◽

Beef Herds ◽

Farm Economics

In beef herds, increasing animal welfare, improving reproductive performance and easing animal management are key goals in farm economics. We explored whether delaying the removal of the intravaginal progesterone device by 24 h in heifers synchronized with a 5d Co-synch 72-h protocol could improve reproductive efficiency of fixed-time artificial insemination (FTAI). In experiment 1, we examined the total synchronization rate (TSR) in cycling Holstein heifers. Heifers (13.4 ± 0.69 mo.) were randomly assigned to the standard 5d Co-synch 56-h protocol (5dCo56; n = 10), 5d Co-synch 72-h (5dCo72; n = 17), or the modified 5d Co-synch 72-h protocol, in which removal of the progesterone device was delayed by 24 h (6dCo48; n = 19). In experiment 2, 309 cycling beef heifers on 18 commercial farms were subjected to the 5d Co-synch 72-h or 6-d Co-synch 48-h protocol and conception rate (CR) studied. In experiment 1, the three protocols led no differences on TSRs of 80.0% (5dCo56), 88.2% (5dCo72), and 89.5% (6dCo48). In experiment 2, the CR from the beef heifers, observed during two consecutive reproductive seasons did not differ: 59.7% for 5dCo72 and 62.0% for 6dCo48 (p = 0.907). Therefore, delaying removal by 24 h provides satisfactory results without reducing reproductive efficiency of heifers.

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Response of beef heifers and non-suckling beef cows to different oestrous synchronization protocols

Animal Science ◽

10.1017/s135772980005270x ◽

2002 ◽

Vol 74 (3) ◽

pp. 547-552 ◽

Cited By ~ 3

Author(s):

D. Cavestany ◽

N. Negrin ◽

R. Negrin ◽

J. F. Groth

Keyword(s):

Beef Cattle ◽

Medroxyprogesterone Acetate ◽

Artificial Insemination ◽

Experimental Period ◽

Fixed Time ◽

Beef Cows ◽

Pregnancy Rates ◽

Gnrh Analogue ◽

Beef Heifers

AbstractThe objective was to evaluate different oestrous synchronization schemes in beef cattle under range conditions. In experiment 1, 202 heifers averaging 26 months of age were assigned randomly to three treatments: (a) GnRH-PG. (no. = 44) day 0 (D0): injection of GnRH; D7: injection of PGF2α; D0 to D25 oestrous detection (OD) and artificial insemination (AI); (b) OD-PG. (no. = 45) D0 to D4; OD + AI; D5: injection of PGF2α; D5 to D25 OD + AI; and (c)Ovsynch. (no. = 113) D0: injection of GnRH; D7: injection of PGF2α; D9: injection of GnRH and 16 h later AI at fixed time. In experiment 2, 318 non-suckling cows were assigned randomly to three treatments: (a) GnRH-PG. (no. = 106) D0: injection of GnRH; D7: injection of PGF2α; D0 to D25 OD + AI; (b) GnRH-MAP-PG. (no. = 106) D0: injection of a GnRH analogue and insertion of an intravaginal sponge impregnated with 250 mg of medroxyprogesterone acetate; D7: injection of PGF2α and sponge withdrawal; D0 to D25 OD + AI; (c) controls. (no. = 106) OD and AI. The experimental period lasted 25 days and, with exception of the Ovsynch treatment, oestrous detection was carried out twice a day (a.m./p.m.) and inseminations performed 12 h later. The pregnancy rates assessed by ultrasonography 30 days after AI were: experiment 1: (a) 30·0%; (b) 28·6% and (c) 62·3% (P < 0·05); experiment 2: (a) 60·2%; (b) 57·8% and (c) 45·5% (P < 0·05). It is concluded that in heifers and non-suckling cows, oestrous synchronization treatments result in higher pregnancy rates. In non-suckling cows, the addition of a progestagen did not improve the response.

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Efficiency of mating, artificial insemination or resynchronisation at different times after first timed artificial insemination in postpartum Nellore cows to produce crossbred calves

Animal Production Science ◽

10.1071/an17466 ◽

2019 ◽

Vol 59 (2) ◽

pp. 225 ◽

Cited By ~ 1

Author(s):

Walvonvitis Baes Rodrigues ◽

Jean do Prado Jara ◽

Juliana Correa Borges ◽

Luiz Orcirio Fialho de Oliveira ◽

Urbano Pinto Gomes de Abreu ◽

...

Keyword(s):

Pregnancy Rate ◽

Breeding Season ◽

Chorionic Gonadotropin ◽

Artificial Insemination ◽

Fixed Time ◽

Beef Cows ◽

Device Removal ◽

Oestradiol Benzoate ◽

Timed Artificial Insemination ◽

Equine Chorionic Gonadotropin

The objective of this trial was to evaluate different post-timed artificial insemination (TAI) reproductive managements in postpartum beef cows to produce crossbred calves from artificial insemination (AI). Nellore cows (n = 607), with 45 days postpartum, were inseminated at a fixed time, using a protocol that included an intravaginal progesterone-releasing device along with oestradiol benzoate, prostaglandin, equine chorionic gonadotropin, and oestradiol cypionate, followed TAI 48 h post-device removal. Four post-TAI treatments were evaluated: in CONTROL (T1, n = 161), cows were exposed to Nellore clean-up bulls until the end of the breeding season (75 days). In OBSERVATION (T2, n = 132), heat detection was performed for 15–25 days post-TAI, followed by AI. In RESYNC22 (T3, n = 157) and RESYNC30 (T4, n = 157), resynchronisation started after 22 or 30 days, following second TAI at Day 32 or 40 days after first TAI. In T2, T3 and T4, after the second AI, cows were exposed to Nellore clean-up bulls until the end of the breeding season (75 days). The pregnancy rate (PR) for the first TAI did not differ (54.6%, 53.0%, 59.2%, and 51.6% for CONTROL, OBSERVATION, RESYNC 22, and RESYNC 30, respectively; P = 0.66), and no difference was observed for the second TAI (RESYNC 22 = 45.31% and RESYNC30 = 46.05%; P = 0.137), in the PR at the end of the breeding season (86.33%, 86.36%, 78.98%, and 81.52%, P = 0.43), or embryonic losses (4.54%, 2.85%, 6.45% and 7.40%, respectively; P = 0.61), but the percentage of crossbred pregnancy was higher in groups with resynchronisation (RESYNC22 and RESYNC30) than CONTROL and OBSERVATION (98.38%, 90.62%, 63.30%, 78.95%, P < 0.001). In conclusion, resynchronisation programs of 22 or 30 days are more efficient to produce AI products, and the final pregnancy rate is similar among the treatments, differing only in the amount of calves produced by AI.

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