Equine chorionic gonadotropin increases fertility of grazing dairy cows that receive fixed-time artificial insemination in the early but not later postpartum period

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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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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REDUCTION OF THE VOLUNTARY WAITING PERIOD BY USE OF HORMONAL PROTOCOLS AND FIXED-TIME ARTIFICIAL INSEMINATION (FTAI) IN DAIRY COWS

Archives of Veterinary Science ◽

10.5380/avs.v17i3.21676 ◽

2012 ◽

Vol 17 (3) ◽

Cited By ~ 1

Author(s):

Miriane Suplicy ◽

Haroldo Suplicy Filho ◽

Luiz Ernandes Kozicki ◽

José Carlos dos Santos Breda ◽

Romildo Romualdo Weiss ◽

...

Keyword(s):

Dairy Cows ◽

Pregnancy Rate ◽

Artificial Insemination ◽

Post Partum ◽

Fixed Time ◽

Estradiol Benzoate ◽

Control Group ◽

Waiting Period ◽

Equine Chorionic Gonadotropin ◽

Voluntary Waiting Period

ABSTRACT: The aim of this study was to reduce the waiting voluntary period in dairy cows by administration of two different hormonal protocols for estrus synchronization and fixed-time artificial insemination (FTAI). One hundred twenty-eight Holstein dairy cows were studied. Three groups (G) were carried out: G1 (44 treated), G2 (34 treated) and G3 (50 as control). In the treated cows the following hormonal protocols was applied between 40 and 45 days post partum: G1- Day 0 (D0) - bovine intravaginal device containing progesterone (P4) plus 1.0 mg of estradiol benzoate (EB), D8 - removal of the P4, plus 0.5 mg of cloprostenol plus 400 IU of equine chorionic gonadotropin (eCG), D9 - 1.0 mg of EB and FTAI after 36 hours. G2 - D0 - P4 intravaginal plus 50 mcg of gonadotropin-releasing hormone (GnRH), D7 - removal of the P4 plus cloprostenol plus 400 IU eCG; D9 - 50 mcg of GnRH and FTAI 16 hours after. G3 – Control group inseminated 12 hours after the visual estrus. Results: G1 and G2 were inseminated (FTAI) respectively in the D55.5 and D56.8 after calving, while the G3 in the D84.5 (p<0.01). The pregnancy rate in the G1, G2 and G3 was respectively 47.0, 46.1 and 35.8% (p>0.05). In Conclusion: there was significant reduction in the voluntary waiting period in treated cows and higher pregnancy rate although not significant.

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Effects of equine chorionic gonadotropin administered via the Baihui acupoint on follicular ovarian dynamics and the luteal function of cattle during an ovulation synchronization treatment regimen for fixed-time artificial insemination

Animal Reproduction Science ◽

10.1016/j.anireprosci.2020.106631 ◽

2020 ◽

Vol 223 ◽

pp. 106631

Author(s):

Lindomar Sousa Brito ◽

Luiz Di Paolo Maggitti Junior ◽

Priscila Assis Ferraz ◽

Isabela Costa Vasconcelos ◽

João Vitor Gomes da Silva Carvalho ◽

...

Keyword(s):

Treatment Regimen ◽

Chorionic Gonadotropin ◽

Artificial Insemination ◽

Fixed Time ◽

Luteal Function ◽

Equine Chorionic Gonadotropin ◽

Ovarian Dynamics

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The use of insulin to improve fertility of timed-inseminated postpartum suckled beef cows

Pesquisa Agropecuária Brasileira ◽

10.1590/s0100-204x2010001000023 ◽

2010 ◽

Vol 45 (10) ◽

pp. 1219-1221 ◽

Cited By ~ 2

Author(s):

Augusto Schneider ◽

Luiz Francisco Machado Pfeifer ◽

Eduardo Schmitt ◽

Ivan Bianchi ◽

Marcelo Brandi Vieira ◽

...

Keyword(s):

Pregnancy Rate ◽

Body Condition ◽

Chorionic Gonadotropin ◽

Artificial Insemination ◽

Body Condition Score ◽

Insulin Injection ◽

Fixed Time ◽

Beef Cows ◽

Condition Score ◽

Equine Chorionic Gonadotropin

The objective of this work was to evaluate the effect of insulin alone or in association with equine chorionic gonadotropin (eCG) on the fertility of postpartum beef cows subjected to synchronization. A total of 340 cows was subjected to fixed time artificial insemination. In the trial 1, the cows were subjected to temporary weaning (TW), while in the trial 2 the same protocol was tested without TW. The addition of an insulin injection to a progesterone/eCG-based protocol without TW increased the pregnancy rate of beef cows with body condition score (BCS) equal to or lower than 2.5. Insulin had no effect on cows submitted to TW or with BCS equal to or higher than 3.0.

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