Effect of peripheral concentrations of progesterone on follicular growth and fertility in ewes

Johnson, Sandra K.; Dailey, R. A.; Inskeep, E. K.; Lewis, P. E.

doi:10.1016/0739-7240(95)00045-3

Cited by 101 publications

(92 citation statements)

References 28 publications

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“…This indicates that high doses of MGA are not the most efficient for its use as a reproductive handling strategy in ewes. Similar results were found [31], when using a high dose of MGA (0.5 mg) during 10 days to evaluate its effect on estrus induction and fertility in 50 goats, finding a response of 73.5% of estrus with a fertility rate of 74%, result that can be explained similarly by the effect of the high dose of MGA on LH secretion and follicular development [21].…”

Section: Resultssupporting

confidence: 74%

“…This suggests that the efficiency of the used dose on the response of estrus manifestation is associated to treatment duration, by the stage of the estrus cycle in the ewes [20] and perhaps, the low fertility observed is due to the fact that the inhibitory effect of ovulation could not be entirely efficient or it could have affected ovarian activity in some ewes, due to the fact that low doses of MGA have shown a negative effect on the pulsatile frequency of LH, can develop persistent dominant follicles [21].…”

Section: Resultsmentioning

confidence: 99%

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Effect of an Intermediate Dose of Melengestrol Acetate (MGA) on Ovulation Inhibition in Ewes

Salas-Razo¹,

Rojo-Martínez²,

Garcidueñas-Piña³

et al. 2014

IJBBB

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Section: Resultssupporting

confidence: 74%

Section: Resultsmentioning

confidence: 99%

Effect of an Intermediate Dose of Melengestrol Acetate (MGA) on Ovulation Inhibition in Ewes

Salas-Razo¹,

Rojo-Martínez²,

Garcidueñas-Piña³

et al. 2014

IJBBB

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“…In contrast, P 4 in a shorter duration treatment maybe maintained at higher levels, which sensitize follicles to grow in normal patterns. Low P 4 concentrations have been associated with formation of persistent follicles, prolonged luteal function and reduced fertility in cattle [14] and [15 ]. Second, the vaginal contamination created following and during the process of sponge insertion.…”

Section: Introductionmentioning

confidence: 99%

The Effects of Short or Long Term FGA Treatment with or without eCG on Reproductive Performance of Ewes Bred Out-of-season

Husein¹,

Ababneh²,

Abu-Ruman³

2007

American J. of Animal and Veterinary Sciences

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Abstract:The objective was to evaluate the effects of intravaginal FGA sponges inserted for 4 or 12 days with or without eCG on reproductive performance of ewes out-of-season. Forty-eight anestrous ewes were assigned in equal numbers to four treatments in a 2x2 factorial design. Ewes were administered with FGA sponges on May 17 for 12 days (12-day-FGA-eCG and 12-day-FGA groups, n= 12 each) and on May 25 for 4 days (4-day-FGA-eCG and 4-day-FGA groups, n= 12 each). All treatments were timed to end together on May 29 (day 0, 0 h) at which time sponges were withdrawn and eCG or saline was injected. Five fertile rams which had been isolated from ewes were joined at 0 h for breeding and estrus detection. Blood samples were collected to compare progesterone (P 4 ) concentrations and for pregnancy diagnosis. Overall estrus expression occurred in 40/48 ewes which differed only between 12-day-FGA-eCG and 4-day-FGA (p<0.05) groups. Intervals from 0 h to onset of estrus were shorter (p<0.05) in 12-day-FGA-eCG than those in 12-day-FGA and 4-day-FGA groups with no differences between 12-day-FGA-eCG and 4-day-FGA-eCG or between 12-day-FGA and 4-day-FGA groups. Progesterone levels were basal from day -12 through day 4 (p>0.1) and increased gradually thereafter until day 15. Progesterone remained elevated through day 19 in 11/12, 8/12, 9/12 and 6/12 ewes, respectively, which were diagnosed pregnant on day 30 by ultrasonography. Of the 34 ewes that became pregnant, 31 lambed 150 days following day 0. Pregnancy loss occurred only in 3 ewes from the two groups that did not have eCG treatment No differences in pregnancy and lambing rates and the number of lambs born were found between 12-day-FGA-eCG and 4-day-FGA eCG. The overall pregnancy and lambing rates obtained from mating at first service were 70.8 and 64.6%, respectively. In conclusion, the 4-day-FGA and eCG regimen could adequately replace the 12-day-FGA out-of-season. Application of such a 4-day-FGA protocol must be accompanied by eCG treatment upon sponge removal.

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“…The results showed that 24 hours after applying PGF2α, 86.66% (4/30) of the progesterone samples exhibited concentrations < 2 ng/mL, and in the G-EB group, only one animal exhibited a concentration of 2.56 ng/ml; all the other animals had concentrations < 2 ng/mL, which indicated that PGF2a was effective in promoting luteolysis. Estrus does not occur until the P4 levels decline to approximately 1 ng/mL (STABENFELDT; HOLT;EWING, 1969;JOHNSON et al 1996). In this study, the pregnancy rate after laparoscopic AI ranged from 11.1% to 66.6%.…”

Section: Groupsmentioning

confidence: 87%

Use of estradiol benzoate to induce ovulation in a short-term protocol for fixed-time AI in sheep

et al. 2015

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The aim of this study was to test the hormonal protocol for fixed-time artificial insemination (TAI) with a progesterone vaginal device for six days applying equine chorionic gonadotropin (eCG) or estradiol benzoate (EB) as an ovulation inducer in ewes. On day 0 (D0), the ewes (n=31) received a device containing 0.33 g of intravaginal progesterone (CIDR ® ) and were divided into three groups. The G-CT (control group) used CIDR for nine days and upon withdrawal of the progesterone, were administered prostaglandin F2 alpha (PGF2α) and eCG. In the eCG (G-eCG) group, CIDR was administered for six days, instead of nine as in the G-CT group, followed by PGF2a and eCG after progesterone withdrawal. In the EB (G-EB) group, CIDR was also administered for six days, but eCG was not applied, and EB was used to induce ovulation 24 hours after removing the CIDR and PGF2a application. TAI was realized in all groups 50 hours after CIDR withdrawal. The pregnancy rate in the G-eCG group (66.66%) was higher (p <0.05) than that in the G-EB group (11.11%). The short-term groups showed no difference (p>0.05) compared to the G-CT group (30%). It is possible to reduce the application time of the progesterone and use eCG for TAI in sheep; however, using EB resulted in a low ovulation rate in the sheep. Key words: Ovine CIDR, laparoscopy, ovulation, serum progesterone ResumoO objetivo do presente estudo foi testar protocolo hormonal para inseminação em tempo fixo (IATF) usando dispositivo de progesterona vaginal por seis dias e aplicação de eCG (gonadotrofina coriônica equina) ou BE (benzoato de estradiol) como indutor de ovulação em ovelhas. No dia 0 (D0), as ovelhas (n=31) receberam CIDR e foram divididas em três grupos. O grupo controle (G-CT) usou CIDR por nove dias e na retirada do dispositivo foi administrado PGF2a e eCG. No grupo eCG (G-eCG), CIDR foi mantido por seis dias, ao invés de nove como no G-CT, com aplicação de PGF2a e eCG na retirada da progesterona. No grupo benzoato de estradiol (G-EB), o CIDR também foi administrado por seis dias, mas não foi utilizado eCG, o BE foi usado para induzir ovulação e foi aplicado 24 horas após a remoção do CIDR e administração de PGF2a. A IATF foi feita em todos os grupos 50h após a retirada do CIDR. A taxa de prenhez do G-eCG (66,66%) foi maior (p <0.05) que no G-EB (11,11%). O grupo G-eCG de curta duração não diferiu (p>0,05) do G-CT (30%). É possível reduzir o tempo de permanência da progesterona usando eCG para IATF em ovelhas, entretanto o uso de BE resultou em baixa taxa de ovulação. Palavras-chave: CIDR ovino, laparoscopia, ovulação, progesterona plasmática

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Effect of peripheral concentrations of progesterone on follicular growth and fertility in ewes

Cited by 101 publications

References 28 publications

Effect of an Intermediate Dose of Melengestrol Acetate (MGA) on Ovulation Inhibition in Ewes

Effect of an Intermediate Dose of Melengestrol Acetate (MGA) on Ovulation Inhibition in Ewes

The Effects of Short or Long Term FGA Treatment with or without eCG on Reproductive Performance of Ewes Bred Out-of-season

Use of estradiol benzoate to induce ovulation in a short-term protocol for fixed-time AI in sheep

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