Comparison of follicular dynamics and hormone concentrations between the 7-day and 5-day CO-Synch + CIDR program in primiparous beef cows

Bridges, G.A.; Mussard, M.L.; Helser, L.A.; Day, M. L.

doi:10.1016/j.theriogenology.2013.11.020

Cited by 34 publications

(30 citation statements)

References 27 publications

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“…It has been demonstrated that maximizing preovulatory estradiol concentrations during the preovulatory period increases the probability of conception in cattle (Bridges et al, 2010(Bridges et al, , 2013. Although this protocol relies on GnRH to reset follicular development at CIDR insertion, which has been demonstrated to have limited effectiveness in beef heifers (Atkins et al, 2008), the 5-d interval from GnRH to PG may limit asynchronous follicular develop ment in females that fail to respond to the initial GnRH administration (Bridges et al, 2000). Previous studies comparing the 5-d approach to other synchronization protocols in beef heifers have demonstrated that the 5-d approach is more effective than the 7-d approach Sparks et al, 2012) and equivalent to a longer progestin approach, the 14-d CIDR Select and FTAI .…”

Section: Discussionmentioning

confidence: 99%

Comparison of three CIDR-based fixed-time AI protocols in beef heifers1

Bridges

Lake

Kruse

et al. 2014

Journal of Animal Science

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Several effective fixed-time AI (FTAI) protocols have been developed to facilitate AI in beef heifers that circumvent the need for estrus detection. Among these are the 5-d CO-Synch + controlled intravaginal progesterone insert (CIDR) protocol (5dCO), PGF2α (PG) 6-d CIDR protocol (PG-6dCIDR), and 14-d CIDR-PG protocol (14dCIDR-PG). Although each of these protocols varies in duration and approach to synchronizing estrus and ovulation, each has been reported as an effective method to facilitate FTAI in beef heifers. Therefore, the objective of this study was to compare FTAI pregnancy rates in beef heifers synchronized with these 3 CIDR-based protocols. Virgin beef heifers (n = 801) at 4 locations were synchronized with 1 of 3 protocols: 1) 5dCO, an injection of GnRH (100 μg) and insertion of a CIDR on d -5, PG (25 mg) and CIDR removal on d 0 with a second injection of PG (>4 h after CIDR removal) on d 0 and FTAI at 72 h after CIDR removal, 2) PG-6dCIDR, PG (25 mg) on d -9, GnRH (100 μg) and insertion of a CIDR on d -6, PG and CIDR removal on d 0, and FTAI at 66 h after CIDR removal, or 3) 14dCIDR-PG, a 14-d CIDR insert from d -30 to -16, PG (25 mg) on d 0, and FTAI at 66 h after PG. All heifers received an injection of GnRH (100 μg) concurrent with FTAI. Timing of treatment initiation was offset to allow all heifers to receive FTAI concomitantly and at random. Pregnancy success was determined between 35 and 40 d after FTAI by transrectal ultrasonography. Blood samples were collected before the beginning of each protocol and at the initiation of each protocol to determine estrous cycling status (77%). Data were analyzed using the GLIMMIX procedures of SAS. As expected, because of the duration of protocols, fewer heifers in the 14dCIDR-PG treatment were pubertal at initiation of synchronization than in the 5dCO (P < 0.05) and PG-6dCIDR (P = 0.10) treatments. Fixed-time AI pregnancy success did not differ between treatments (P = 0.14; 62.6%, 56.9%, and 53.3% for 5dCO, PG-6dCIDR, and 14dCIDR-PG, respectively). However, heifers that had reached puberty by initiation of synchronization had greater (P < 0.01) pregnancy success compared to heifers that were prepubertal (60.7% and 47.3%, respectively). In summary, all 3 protocols had similar FTAI pregnancy success, and puberty status had the greatest impact on pregnancy success.

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Section: Discussionmentioning

confidence: 99%

Comparison of three CIDR-based fixed-time AI protocols in beef heifers1

Bridges

Lake

Kruse

et al. 2014

Journal of Animal Science

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“…In vivo-derived embryos have greater viability than those produced in vitro (Bridges, Mussard, Helser, & Day, 2009;Lonergan, 2007;Ulloa et al, 2008). This difference is mainly due to the lower quality and competency of oocytes that undergo in vitro maturation (IVM), suggesting that improving IVM might increase the efficacy of the in vitro production (IVP) system (Demyda-Peyrás et al, 2013).…”

Section: Introductionmentioning

confidence: 99%

Transporting bovine oocytes in a medium supplemented with different macromolecules and antioxidants: Effects on nuclear and cytoplasmic maturation and embryonic development in vitro

Ambrogi

Dall’Acqua

Rocha-Frigoni

et al. 2017

Reprod Domestic Animals

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We investigated whether supplementing the medium used to transport bovine oocytes with different macromolecules [foetal calf serum (FCS) or bovine serum albumin (BSA)] or a mixture of antioxidants (cysteine, cysteamine and catalase) affects their nuclear and cytoplasmic maturation and thereby affects their subsequent embryonic development and cryotolerance. Oocytes were transported for 6 hr in a portable incubator and then subjected to standard in vitro maturation (IVM) for 18 hr. The oocytes in the control groups were cultured (standard IVM) for 24 hr in medium containing 10% FCS (Control FCS) or 10% FCS and the antioxidant mixture (Control FCS+Antiox). The intracellular concentrations of reactive oxygen species (ROS) at the end of IVM period were lower in the oocytes subjected to simulated transport in the presence of a macromolecular supplement or the antioxidant mixture than that of the control group (FCS: 0.62 and BSA: 0.66 vs. Control FCS: 1.00, p < .05; and Transp: 0.58 and Transp Antiox: 0.70 vs. Control FCS: 1.00, p < .05). After IVM, the mitochondrial membrane potentials of the transported oocytes were lower than those of the non-transported oocytes (FCS: 0.41 and BSA: 0.57 vs. Control FCS: 1.00, p < .05; and Transp: 0.48 and Transp Antiox: 0.51 vs. Control FCS: 1.00 and Control Antiox: 0.84, p < .05). The blastocyst formation rates (36.9% average) and the re-expansion rates of vitrified-warmed blastocysts (53%, average) were unaffected (p > .05) by the treatments. In conclusion, supplementing the medium in which bovine oocytes are transported with antioxidants or different macromolecules did not affect their in vitro production of embryos or their cryotolerance.

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“…While PGF2α requirements have been definitively identified, the requirement of G1 in 5dCO has not been challenged to date. Gonadotropin releasing hormone is theoretically required to synchronize ovulatory follicular wave initiation; however, response rate of beef cows to GnRH is widely variable in both cycling and anestrus beef cows (Geary et al, 2000;Atkins et al, 2010a;Atkins et al 2010b;Bridges et al, 2014).…”

Section: Generalmentioning

confidence: 99%

“…The administration of G1 is used to synchronize ovarian follicular growth at the start of the FTAI protocol as to better time and synchronize ovulation for optimal FTAI success. However, in beef cows, the response rate to a single GnRH injection is widely variable and ranges on average from 66 to 70% in both cycling and anestrus females (Geary et al, 2000;Atkins et al, 2010a;Atkins et al 2010b;Bridges et al, 2014). The failure of response to the initial injection of GnRH has proven to be detrimental to pregnancy rates within the 7-d CO-Synch + CIDR protocol by leading to either smaller, immature dominant follicles (Lamb et al, 2001;Vasconcelos et al, 2001;Perry et al, 2005;Atkins et al, 2010a;Atkins et al 2010b) with decreased estradiol and progesterone concentrations or persistent follicles that are compromised in terms of both oocyte competence and steroidogenesis .…”

Section: Introductionmentioning

confidence: 99%

“…The design of the standard 5dCO more appropriately accommodates females that do not respond to G1 by shortening the period between G1 and corresponding CIDR removal and PGF2α administration compared to the 7-d protocol (Bridges et al, 2008;Bridges et al, 2014). Therefore, the oocytes that do not respond to G1 would be younger and more competent.…”

Section: Introductionmentioning

confidence: 99%

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Effects of initial GnRH removal from 5-d CO-Synch + CIDR protocol on ovarian parameters and fixed timed artificial insemination pregnancy rates in beef cattle

Grussing¹

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Comparison of follicular dynamics and hormone concentrations between the 7-day and 5-day CO-Synch + CIDR program in primiparous beef cows

Cited by 34 publications

References 27 publications

Comparison of three CIDR-based fixed-time AI protocols in beef heifers1

Comparison of three CIDR-based fixed-time AI protocols in beef heifers1

Transporting bovine oocytes in a medium supplemented with different macromolecules and antioxidants: Effects on nuclear and cytoplasmic maturation and embryonic development in vitro

Effects of initial GnRH removal from 5-d CO-Synch + CIDR protocol on ovarian parameters and fixed timed artificial insemination pregnancy rates in beef cattle

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