Influence of inducing luteal regression before a modified fixed-time artificial insemination protocol in postpartum beef cows on pregnancy success1

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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Influence of estradiol on bovine trophectoderm and uterine gene transcripts around maternal recognition of pregnancy

Biology of Reproduction ◽

10.1093/biolre/ioab091 ◽

2021 ◽

Author(s):

Emmalee J Northrop-Albrecht ◽

Jerica J J Rich ◽

Robert A Cushman ◽

Runan Yao ◽

Xijin Ge ◽

...

Keyword(s):

Artificial Insemination ◽

Mrna Level ◽

Fixed Time ◽

Beef Cows ◽

Differentially Expressed ◽

Differentially Expressed Proteins ◽

Rt Pcr ◽

Embryo Survival ◽

Uterine Fluid ◽

Gene Transcripts

Abstract Embryo survival and pregnancy success is increased among animals that exhibit estrus prior to fixed time artificial insemination (AI), but there are no differences in conceptus survival to d16. The objective of this study was to determine effects of preovulatory estradiol on uterine transcriptomes, select trophectoderm transcripts, and uterine luminal fluid (ULF) proteins. Beef cows/heifers were synchronized, artificially inseminated (d0), and grouped into either high (highE2) or low (lowE2) preovulatory estradiol. Uteri were flushed (d16); conceptuses and endometrial biopsies (n = 29) were collected. RNA sequencing was performed on endometrium. Real-Time PCR (RT-PCR) was performed on trophectoderm (TE; n = 21) RNA to measure relative abundance of IFNT, PTGS2, TM4SF1, C3, FGFR2, and GAPDH. Uterine fluid was analyzed using 2D LC–MS/MS based iTRAQ method. RT-PCR data were analyzed using the MIXED procedure in SAS. There were no differences in mRNA abundances in TE, but there were 432 differentially expressed genes (DEGs) (253 downregulated, 179 upregulated) in highE2/conceptus versus lowE2/conceptus groups. There were also 48 differentially expressed proteins (DEPs; 19 upregulated, 29 downregulated), 6 of these were differentially expressed (FDR < 0.10) at the mRNA level. Similar pathways for mRNA and proteins included: calcium signaling, protein kinase A signaling, and corticotropin releasing hormone (CRH) signaling. These differences in uterine function, may be preparing the conceptus for improved likelihood of survival after d16 among highE2 animals.

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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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1113 Comparing fixed-time artificial insemination to split-time artificial insemination with delayed administration of GnRH in postpartum beef cows

Journal of Animal Science ◽

10.2527/jam2016-1113 ◽

2016 ◽

Vol 94 (suppl_5) ◽

pp. 533-534

Author(s):

B. E. Bishop ◽

J. M. Abel ◽

J. M. Thomas ◽

M. F. Smith ◽

S. E. Poock ◽

...

Keyword(s):

Artificial Insemination ◽

Fixed Time ◽

Beef Cows ◽

Split Time

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Altered progesterone concentrations by hormonal manipulations before a fixed-time artificial insemination CO-Synch + CIDR program in suckled beef cows

Theriogenology ◽

10.1016/j.theriogenology.2014.03.008 ◽

2014 ◽

Vol 82 (1) ◽

pp. 104-113 ◽

Cited By ~ 14

Author(s):

S.L. Hill ◽

G.A. Perry ◽

V.R.G. Mercadante ◽

G.C. Lamb ◽

J.R. Jaeger ◽

...

Keyword(s):

Artificial Insemination ◽

Fixed Time ◽

Beef Cows

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Use of Gonadotropin-Releasing Hormone at Fixed-Time Artificial Insemination at Eighty or Ninety-Seven Hours Post Prostaglandin F2α in Beef Cows Administered the Long-Term Melengestrol Acetate Select Synch

The Professional Animal Scientist ◽

10.15232/s1080-7446(15)30715-4 ◽

2009 ◽

Vol 25 (3) ◽

pp. 256-261

Author(s):

J.K. Ahola ◽

G.E. Seidel ◽

J.C. Whittier

Keyword(s):

Artificial Insemination ◽

Prostaglandin F2α ◽

Fixed Time ◽

Beef Cows ◽

Gonadotropin Releasing Hormone ◽

Releasing Hormone ◽

Melengestrol Acetate

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107 Timing of progesterone exposure effects pregnancy rates following fixed time artificial insemination in postpartum beef cows

Journal of Animal Science ◽

10.1093/jas/skz053.098 ◽

2019 ◽

Vol 97 (Supplement_1) ◽

pp. 43-44

Author(s):

Anna L Smith ◽

Rebecca K Poole ◽

Kyle Mayberry ◽

McKayla A Newsome ◽

Harrison B Dudley ◽

...

Keyword(s):

Artificial Insemination ◽

Statistical Significance ◽

Fixed Time ◽

Beef Cows ◽

Reproductive Technologies ◽

Pregnancy Rates ◽

Estrous Synchronization ◽

Pregnancy Status ◽

Timed Artificial Insemination ◽

The Impact

Abstract Advancements in reproductive technologies have improved pregnancy rates in postpartum cows; however, undesirable consequences leading to reduced fertility still occur. Thus, the objectives were to determine if presence of a corpus luteum (CL) at the start of estrous synchronization (AIM1) or if the length of proestrus (interval from progesterone removal to a GnRH-induced LH surge; AIM2) alters fixed timed artificial insemination (FTAI) pregnancy rates. Cycling postpartum cows (n = 285) at two locations were synchronized using the CO-Synch+CIDR® FTAI protocol. Ultrasonographic measurements of luteal area were recorded at CIDR insertion. To determine the impact of proestrus length, cows were randomly assigned to either undergo CIDR removal at the time of PGF2a injection (long proestrus, n = 145), or CIDR removal 24 hours post PGF2a injection (short proestrus, n = 140). Blood samples were collected at CIDR insertion and at insemination for progesterone (P4) analysis. Pregnancy status to FTAI was assessed using ultrasonographic diagnosis at 30 d post insemination. Data were analyzed using a MIXED procedure of SAS and examined for effects of length of proestrus, P4 concentration, luteal area, sire, location, and age. Statistical significance was determined at P0.05) pregnancy rates. Pregnancy rates were greater in cows with >1 ng/mL P4 compared to cows with 0.05). Cows > 4 y old had higher AI pregnancy rates compared to 2–3 y cows (70.2±7.4 vs. 51±5.8%, respectively; P > 0.05). Based on these data, incorporating a presynchronization program to ensure the presence of a functional CL at the start of a FTAI protocol may improve pregnancy success in postpartum beef cows.

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