Evidence that progesterone may influence subsequent luteal function in the ewe by modulating preovulatory follicle development

McLeod, B. J.; Haresign, W.

doi:10.1530/jrf.0.0710381

Cited by 71 publications

(41 citation statements)

References 7 publications

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“…The increase in progesterone is related to the new corpora lutea formed following the GnRH-induced ovulation. The corpus luteum that forms after GnRH administration is capable of undergoing PGF 2α -induced luteolysis following 5 days in goats [23] and sheep [24,25]. Whereas, 33.3% and 44.4% of the goats in groups GPE and GP, respectively, had basal progesterone levels on day 0 due to ovulation failure following the GnRH treatment and therefore, did not respond to the PGF 2α injection.…”

Section: Discussionmentioning

confidence: 99%

The effects of progesterone priming on reproductive performance of GnRH-PGF2α-treated anestrous goats

2005

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-The objective of this experiment was to determine the effect of a 5-day progesterone priming prior to a GnRH-PGF 2α treatment on reproductive performance of anestrous goats. Thirtysix Mountain Black goats were randomly assigned in a 2 × 2 factorial arrangement and were administered intravaginally on day -12, either with 300 mg progesterone inserts (CGPE and CGP) or with 0 mg progesterone (GPE and GP) for 5 days. On day -6, the goats were injected with 100 µg GnRH, followed 6 days later by 15 mg PGF 2α (day 0), the time at which the goats in the CGPE and GPE groups were administered 300 IU eCG injections and those in CGP and GP groups were administered the control solution. The goats were exposed to four fertile bucks at 0 h and were checked for breeding marks at 6-h intervals for 72 h. Blood samples were collected from all goats for progesterone analysis. Progesterone concentrations increased only in CGPE and CGP during the period of device insertion but remained low in GPE and GP groups (P < 0.001). Progesterone levels at the time of GnRH injection on day -6 were basal (0.2 ± 0.04 ng·mL -1 ) among the groups and began to increase starting on day -2. Day 0 progesterone concentrations differed (P < 0.05) among groups and were significantly influenced by CIDR-G (P < 0.001). A similar proportion of goats expressed estrus and intervals to detected estrus were shorter (P < 0.05) in the CGPE and GPE groups than in GP with no difference between the CGPE, CGP and GPE or between CGP and GP groups. The number of goats ovulating based upon elevated progesterone levels on day 0 was significantly greater (P = 0.002) in CGPE (9/9) and CGP (9/9) than GPE (6/9) and GP (5/9) groups and was significantly influenced by CIDR-G (P = 0.03). All pregnant goats had elevated progesterone concentration on day 0 and none of the goats with basal progesterone levels became pregnant. Pregnancy and kidding rates, twinning percentage and the number of kids born per goat exposed were greater (P < 0.05) among goats treated with progesterone and eCG. In conclusion, progesterone priming and eCG are essential for producing higher rates of pregnancy and kidding in GnRH-PGF 2α -treated anestrous goats.

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Section: Discussionmentioning

confidence: 99%

The effects of progesterone priming on reproductive performance of GnRH-PGF2α-treated anestrous goats

2005

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“…Although Guinness et al (1971) have claimed that silent ovulations before the first oestrus of the breeding season do not occur in the red deer hind, the phenomenon has been described in other seasonal ungulates (sheep: Walton et al, 1977; fallow deer: Asher, 1985). In the ewe it has been shown that progesterone priming is essential to ensure normal luteal function at the subsequent ovulation (McLeod et al, 1982;McLeod & Haresign, 1984). In addition, Legan et al (1985) have shown that some of the priming effects of progesterone require only low physiological concentrations of progesterone for as little as 3 days.…”

Section: Discussionmentioning

confidence: 99%

Oestrous cycles and the breeding season of the Pere David's deer hind (Elaphurus davidianus)

Curlewis

Loudon²,

Coleman³

1988

Reproduction

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Summary. Reproductive cycles were studied in a group of tame P\l=e`\reDavid's deer hinds. The non-pregnant hind is seasonally polyoestrous and, in animals studied over 2 years, the breeding season began in early August (2 August \ m=+-\ 3\m=.\3days; s.e.m., N = 9) and ended in mid-December (18 December \m=+-\5\m=.\7 days; N = 8) and early January (6 January \ m=+-\3\m=.\2days; N = 11) in consecutive years. During the anoestrous period, plasma progesterone concentrations were low (0\m=.\2\ m=+-\ 0\m=.\01 ng/ml) or non-detectable. During the breeding season, experiments were conducted to investigate synchronization of oestrus with exogenous progestagens. Oestrus occurred 32\p=n-\90h after progestagen removal. The changes in plasma progesterone concentrations which followed oestrus were similar to those seen after natural oestrus.

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“…The findings that pulsatile administration of GnRH to anoestrous ewes at low to intermediate follicular phase frequencies can initiate cycles rapidly, within 2-3 days (McNatty et al, 1982;McLeod et ai, 1982a, b;McLeod & Haresign, 1984;Legan et ai, 1985a, b), strongly suggest that the first increase in LH pulse frequency at the end of anoestrus may occur within a few days. Such a rapid change in response to oestradiol negative feedback would contrast markedly with the steroid-independent seasonal change in LH pulse frequency observed in ovariectomized ewes, which takes place over several months (Robinson et ai, 1985).…”

Section: Introductionmentioning

confidence: 99%

Changes in LH pulse frequency and serum progesterone concentrations during the transition to breeding season in ewes

I’Anson

Legan²

1988

Reproduction

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Summary. To characterize the changes in LH pulse frequency during the transition to breeding season, LH pulse patterns and serum progesterone profiles were determined in 8 intact ewes from mid-anoestrus to the early breeding season. Overall, 8 increases in LH pulse frequency were observed and these were restricted to 5 ewes. Of the 8 increases, 7 occurred during the 4 weeks before the first cycle, 5 of them within 1 week after a pulse frequency typical of anoestrus (0\p=n-\2per 8 h). Six of them occurred less than 1 week before either a full-length luteal phase (n = 2) or a 1\p=n-\3-day increment in progesterone (n = 4). Seven of these brief progesterone increases were observed in 6 ewes, 5 of them immediately preceding the first full-length luteal phase. These results are consistent with the hypothesis that the seasonal decrease in response to oestradiol negative feedback at the beginning of the breeding season causes an increase in GnRH, and thereby LH pulse frequency. In addition, they demonstrate that the first increase in tonic LH secretion occurs in < 1 week and, in most ewes, initiates either the first fulllength cycle or a transient increase in progesterone, the latter occurring more often.

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Evidence that progesterone may influence subsequent luteal function in the ewe by modulating preovulatory follicle development

Cited by 71 publications

References 7 publications

The effects of progesterone priming on reproductive performance of GnRH-PGF2α-treated anestrous goats

The effects of progesterone priming on reproductive performance of GnRH-PGF2α-treated anestrous goats

Oestrous cycles and the breeding season of the Pere David's deer hind (Elaphurus davidianus)

Changes in LH pulse frequency and serum progesterone concentrations during the transition to breeding season in ewes

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