scholarly journals 129 Split-time artificial insemination improves estrous response and pregnancy rates following administration of the MGA-PG protocol to synchronize estrus in beef heifers.

2018 ◽  
Vol 96 (suppl_3) ◽  
pp. 345-345
Author(s):  
E Knickmeyer ◽  
J Thomas ◽  
J Locke ◽  
R Bonacker ◽  
M Ellersieck ◽  
...  
Keyword(s):  
Artificial Insemination ◽  
Pregnancy Rates ◽  
Beef Heifers ◽  
Split Time

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

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.

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

2002 ◽  
Vol 74 (3) ◽  
pp. 547-552 ◽  
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.

Evaluation of split-time artificial insemination following administration of a long or short-term progestin-based estrus synchronization protocol in beef heifers

2019 ◽  
Vol 133 ◽  
pp. 179-186 ◽  
Author(s):  
E.R. Knickmeyer ◽  
J.M. Thomas ◽  
J.W.C. Locke ◽  
R.C. Bonacker ◽  
M.R. Ellersieck ◽  
...  
Keyword(s):  
Artificial Insemination ◽  
Estrus Synchronization ◽  
Beef Heifers ◽  
Short Term ◽  
Split Time ◽  
Synchronization Protocol

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

2010 ◽  
Vol 90 (1) ◽  
pp. 23-34 ◽  
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

Evaluation of later timepoints for split-time artificial insemination when using sex-sorted semen among beef heifers following the 14-d CIDR®-PG protocol

2021 ◽  
Vol 224 ◽  
pp. 106649
Author(s):  
J.N. Ketchum ◽  
R.C. Bonacker ◽  
C.M. Andersen ◽  
E.G. Smith ◽  
K.S. Stoecklein ◽  
...  
Keyword(s):  
Artificial Insemination ◽  
Beef Heifers ◽  
Split Time

136 Administration of recombinant bovine somatotropin prior to fixed-time artificial insemination and the effects on pregnancy rates and conceptus development in beef heifers

2017 ◽  
Vol 95 (suppl_4) ◽  
pp. 67-67
Author(s):  
N. Oosthuizen ◽  
P. L. P. Fontes ◽  
D. D. Henry ◽  
C. D. Sanford ◽  
F. M. Ciriaco ◽  
...  
Keyword(s):  
Artificial Insemination ◽  
Fixed Time ◽  
Pregnancy Rates ◽  
Bovine Somatotropin ◽  
Beef Heifers ◽  
Recombinant Bovine Somatotropin ◽  
Conceptus Development

Split-time artificial insemination in beef cattle: I–Using estrous response to determine the optimal time(s) at which to administer GnRH in beef heifers and postpartum cows

2016 ◽  
Vol 86 (4) ◽  
pp. 1102-1110 ◽  
Author(s):  
B.E. Bishop ◽  
J.M. Thomas ◽  
J.M. Abel ◽  
S.E. Poock ◽  
M.R. Ellersieck ◽  
...  
Keyword(s):  
Beef Cattle ◽  
Artificial Insemination ◽  
Optimal Time ◽  
Beef Heifers ◽  
Split Time

scholarly journals PSXIII-22 Modeling the optimal time point at which to perform timed artificial insemination

2019 ◽  
Vol 97 (Supplement_3) ◽  
pp. 371-371
Author(s):  
Jordan M Thomas ◽  
William R Lamberson ◽  
John B Hall
Keyword(s):  
Mathematical Model ◽  
Pregnancy Rate ◽  
Artificial Insemination ◽  
Pregnancy Rates ◽  
Optimal Time ◽  
Estrus Synchronization ◽  
Time Points ◽  
Optimal Time Point ◽  
Split Time ◽  
Time Point

Abstract Timing of artificial insemination (AI) critically impacts likelihood of pregnancy success. In modern timed AI protocols for cattle, AI is performed at a predetermined time point following estrus synchronization. As a result, there may be significant variation among cows or heifers in estrous status and in timing of insemination relative to estrus onset. Recommendations as to when timed AI should be performed are formulated based on research trials evaluating alternative time points. However, available data are limited, as such trials are costly and require large numbers to detect significant differences. As an alternative approach, a mathematical model was developed to predict the anticipated aggregate pregnancy rate to timed AI based on the hour at which timed AI is performed. Previously published distributions of estrus onset were compiled separately for two long-term progestin-based protocols for beef heifers (MGA-PG and 14-d CIDR-PG). Probability of pregnancy was modeled using a regression equation for fertility based on timing of AI in relation to timing of estrus, with heifers grouped in one hour time blocks. Based on a previously published meta-analysis that compiled pregnancy rates when timed AI was performed prior to onset of estrus, a reduced pregnancy rate was assigned to heifers for which timed AI would be performed prior to anticipated estrus expression. Modeled pregnancy rates based on timing of AI were plotted for each protocol. Additionally, use of a split-time AI versus fixed-time AI approach was modeled, as well as predicted impact of varying intervals between the two time points used for split-time AI. Modeled cumulative estrous response and aggregate pregnancy rates were compared to published data for the MGA-PG and 14-d CIDR-PG protocols. Results suggest a mathematical model may be useful to determine the optimal time point at which to perform timed AI following estrus synchronization.

Effects of prostaglandin F2α administration at CIDR insertion on artificial insemination pregnancy rates in beef heifers

2012 ◽  
Vol 28 (5) ◽  
pp. 552-559 ◽  
Author(s):  
B.L. Sparks ◽  
S.L. Lake ◽  
P.J. Gunn ◽  
K.S. Fisher ◽  
L.A. Horstman ◽  
...  
Keyword(s):  
Artificial Insemination ◽  
Prostaglandin F2α ◽  
Pregnancy Rates ◽  
Beef Heifers
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