177 resultados para Prostaglandin E


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Pós-graduação em Ciências Biológicas (Farmacologia) - IBB

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Pós-graduação em Medicina Veterinária - FMVZ

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Pós-graduação em Medicina Veterinária - FMVZ

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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The objective of this study was to determine the effect of age of the ovulatory follicle on fertility in beef heifers. Ovulation was synchronized with the 5 d CO-Synch + controlled intravaginal drug release (CIDR) program in heifers in Montana (MT; n = 162, Hereford and Angus Crossbred) and Ohio (OH; n = 170, Angus Crossbred). All heifers received estradiol benzoate (EB; 1 mg/500 kg BW, [i.m.]) 6 d after the final GnRH of the synchronization program to induce follicular atresia and emergence of a new follicular wave (NFW) followed by prostaglandin F2 alpha (PGF(2 alpha); 25 mg, i.m.) administration either 5 d (young follicle [YF]; n = 158) or 9 d (mature follicle [MF]; n = 174) after EB. Estrous detection was performed for 5 d after PGF(2 alpha) with AI approximately 12 h after onset of estrus. Ovarian ultrasonography (MT location only) was performed in YF and MF at EB, 5 d after EB, PGF(2 alpha), and AI. Heifers in MT (n = 20) and OH (n = 18) that were not presynchronized or did not initiate a NFW were excluded from further analyses, resulting in 142 and 152 heifers in MT and OH, respectively. Heifers from the MF treatment in MT that initiated a second NFW after EB but before PGF(2 alpha) (MF2; n = 14) were excluded from the primary analysis. In the secondary analysis, the MF2 group was compared to MF and YF treatments in MT. Estrous response was similar (90%; 252/280) between treatments and locations. Proestrus interval (from PGF(2 alpha) to estrus) and age of the ovulatory follicle at AI were similar for MF heifers between locations (54.6 +/- 1.7 h and 8.3 +/- 0.07 h) but were greater (P < 0.01) for YF heifers in OH (78.5 +/- 1.4 h and 5.3 +/- 0.06 h) than MT (67.4 +/- 1.6 h and 4.8 +/- 0.06 h; treatment x location, P < 0.01). However, conception rate did not differ for MF (63.8%; 74/116) and YF (67.0%; 91/136) treatments. In the MT heifers, follicle size and follicle age atAI in the YF treatment (10.4 +/- 0.15 mm and 4.8 +/- 0.06 d, respectively) was less (P < 0.01) than in the MF treatment (11.0 +/- 0.18 mm and 8.3 +/- 0.11 d, respectively), but conception rate to AI did not differ between treatments in MT. In the MF2 group proestrus interval was greater (P < 0.01); hence, diameter of the ovulatory follicle and age were similar to that for the YF treatment. Conception rate to AI did not differ between MF2, MF, and YF (61.5, 63.3, and 64.7%, respectively) in MT. In conclusion, manipulation of age of the nonpersistent ovulatory follicle at spontaneous ovulation did not influence conception rate.

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The effect of the age of the ovulatory follicle on fertility in beef cows was investigated. Multiparous (n = 171) and primiparous (n = 129) postpartum beef cows in 2 groups (G1 and G2) received estradiol benzoate (EB; 1 mg/500 kg BW, intramuscular [i.m.]) 5.5 d (G1; n = 162) and 6.5 d (G2; n = 138) after the final GnRH of a synchronization program (5d CO-Synch + CIDR) to induce emergence of a new follicular wave (NFW), followed by prostaglandin F2 alpha (PGF2 alpha; 25 mg, i.m.) administration either 5.5 d (young follicle, YF; n = 155) or 9.5 d (mature follicle, MF; n = 145) after EB. Estrous detection coupled with AI 12 h later (estrus-AI) was performed for 60 h (MF) and 84 h (YF) after PGF(2 alpha); cows not detected in estrus within this period received timed AI (TAI) coupled with GnRH at 72 and 96 h, respectively. Within the first 72 h after PGF(2 alpha), more (P < 0.01) cows in the MF (76.3%) than YF treatment (47.7%) exhibited estrus, but through 96 h, the proportion detected in estrus (P < 0.05) and interval from PGF(2 alpha) to estrus (P < 0.01) were greater in the YF than MF treatment (88.6% vs. 76.3%, 78.9 +/- 0.8 vs. 57.5 +/- 1.6 h, respectively). Age of the ovulatory follicle at AI was greater (P < 0.01) in the MF (9.32 +/- 0.04 d) than YF (6.26 +/- 0.02 d) treatment, but follicle diameter at AI and pregnancy rates did not differ between MF (13.1 +/- 0.2 mm; 72.0%) and YF (12.9 +/- 0.1 mm; 67.1%) treatments. Regardless of treatment, the diameter of the ovulatory follicle at AI and pregnancy rate were greater (P < 0.01) with estrus-AI (13.1 +/- 0.1 mm; 75.0%) than TAI (12.6 +/- 0.2 mm; 55.4%). Cows in the MF treatment that initiated a second NFW after EB but before PGF(2 alpha) (MF2; n = 47) were induced to ovulate with GnRH and TAI at 72h, when ovulatory follicles were 4 d old and 10.2 +/- 0.2 mm in diameter. Pregnancy rate for TAI (51.1%) in MF2 did not differ from TAI pregnancy rate (55.4%) across the MF and YF treatments. In summary, the age of the ovulatory follicle affected interval to estrus and AI but did not influence pregnancy rate in suckled beef cows.

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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Currently, timed ovulation induction and timed artificial insemination (TAI) can be performed in buffalo using GnRH or estradiol plus progesterone/progestin (P4)-releasing devices and prostaglandin F-2 alpha (PGF(2 alpha)). The control of the emergence of follicular waves and of ovulation at predetermined times, without the need for estrus detection, has facilitated the management and improved the efficiency of AI programs in buffalo during the breeding and nonbreeding season. Multiple ovulations, embryo transfer, ovum collection and in vitro embryo production have been shown to be feasible in buffalo, although low efficiency and limited commercial application of these techniques have been documented as well. These results could be associated with low ovarian follicular pools, high levels of follicular atresia and failures of the oocyte to enter the oviduct after superstimulation of follicular growth. This review discusses a number of key points related to the manipulation of ovarian follicular growth to improve pregnancy rates following TAI and embryo transfer of in vivo- and in vitro-derived embryos in buffalo.

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In cattle, proestrus begins with the initiation of luteolysis and ends with initiation of estrus and the GnRH/LH surge. This period is marked by a dramatic decrease in circulating progesterone (P4) that reaches a nadir by about 36-48 h in cows undergoing natural or prostaglandin F2 alpha (PGF)-induced luteolysis. Inadequate luteolysis is a cause of reduced fertility particularly in timed AI programs with small elevations in circulating P4 reducing fertility. Increasing circulating estradiol (E2) during proestrus is dependent on presence, size, and function of the dominant follicle and this varies during natural proestrus, due to whether animals have two or three follicular waves, and during PGF-induced proestrus, according to stage of the follicular wave at time of PGF treatment. Inadequate circulating E2 can limit fertility and increase pregnancy loss in some specific circumstances such as in cows with low BCS and in cows during heat stress. Thus, studies to optimize the length of proestrus and the concentrations of E2 and P4 during proestrus could produce substantial improvements in fertility and reductions in pregnancy loss.

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)