Origin of the preovulatory follicle after induced luteolysis during the early luteal phase in ewes

Viñoles, C.; Rubianes, E.

doi:10.4141/a98-015

Cited by 21 publications

(10 citation statements)

References 8 publications

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“…This is consistent with previous studies carried out in ewes and cows treated with prostaglandin F2 α for oestrus synchronization (Stevenson et al. 1998; Viñoles and Rubianes 1998). These studies showed that ovulation was advanced in those animals whose largest follicles were in a growing phase at induced luteolysis.…”

Section: Discussionsupporting

confidence: 93%

“…Thus, ewes with an LF1 which decreased in size, and thus was in the decreasing phase at start the FSH treatment showed a delay in LH surge and ovulation time of around 10-12 h when compared with females with a growing LF1. This is consistent with previous studies carried out in ewes and cows treated with prostaglandin F2a for oestrus synchronization (Stevenson et al 1998;Vin˜oles and Rubianes 1998). These studies showed that ovulation was advanced in those animals whose largest follicles were in a growing phase at induced luteolysis.…”

Section: Discussionsupporting

confidence: 93%

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Timing of Preovulatory LH Surge and Ovulation in Superovulated Sheep are Affected by Follicular Status at Start of the FSH Treatment

Veiga-López¹,

Encinas²,

McNeilly³

et al. 2007

Reprod Domestic Animals

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The aims of this study were to evaluate the chronology of periovulatory events (oestrus behaviour, LH surge and ovulation) in 16 superovulated Manchega sheep and to determine whether follicular status at start of the FSH supply might affect their occurrence. Mean timing for onset of oestrus behaviour was detected at 28.1 +/- 0.7 h after sponge withdrawal; the preovulatory LH surge and ovulation started at 37.2 +/- 0.7 h and 65.4 +/- 0.7 h after progestagen withdrawal, respectively. The intervals between oestrus, LH surge and ovulation were affected by a high individual variability, which might be the cause for reported decreased efficiency in embryo production. Current results also addressed the role of follicular status at start of the superovulatory treatment on the preovulatory LH surge and the ovulation. The interval LH surge-ovulation was increased in ewes with a growing dominant follicle at starting the FSH treatment (32.3 +/- 0.9 vs 28.6 +/- 0.5 h, p < 0.05). The developmental stage of the largest follicle at starting the superovulatory treatment also affected occurrence of LH surge and ovulation; follicles in growing phase advanced the occurrence of the LH surge and ovulation when compared to decreasing follicles (33.0 +/- 1.0 vs 43.5 +/- 1.1 h, p < 0.05, for LH peak and 60.7 +/- 1.1 vs 72.8 +/- 1.2 h, p < 0.05, for ovulation). Thus, only ewes with growing follicles ovulated prior to 55 h after sponge withdrawal; conversely, no sheep with decreasing follicles ovulated earlier than 67 h, when an 85.7% of the ewes bearing growing follicles has ovulated at 63 h.

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Section: Discussionsupporting

confidence: 93%

Section: Discussionsupporting

confidence: 93%

Timing of Preovulatory LH Surge and Ovulation in Superovulated Sheep are Affected by Follicular Status at Start of the FSH Treatment

Veiga-López¹,

Encinas²,

McNeilly³

et al. 2007

Reprod Domestic Animals

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“…This day was close to the day of luteolysis, and the occurrence of a recruitment and selection phase of preovulatory follicles following a prostaglandin application, which has been also observed by Maracek et al (2002) in sheep. These results are also in accord with those obtained by Viñoles and Rubianes (1998) in Corriedale sheep. In this monovular breed, when estrous was induced by prostaglandin on Day 5 or 9 of the estrous cycle, the preovulatory follicle originated from the first follicular wave when the dominant follicle was in its growth phase or attaining maximum diameter.…”

Section: Discussionsupporting

confidence: 93%

Follicular dynamics in Serrana goats

Simões

Almeida

Valentim

et al. 2006

Animal Reproduction Science

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Twenty-two Serrana goats were studied through two successive estrous cycles in order to characterize their follicular dynamics during the breeding season. The ovaries of the goats were scanned daily by realtime ultrasonography and all follicles ≥3 mm were measured and classified. The data were classified by the number of follicular waves per goat to test the hypothesis that temporal and morphological differences between the last follicular wave of an ovary, irrespective of ovulation, will affect the selection of the next ovulatory wave.The mean interovulatory interval was 20.7 ± 1.0 days (mean ± S.D.). Three to five waves per estrous cycle were observed and 61.3% (19/31) of cycles had four waves. In estrous cycles with four waves, the day of onset of the first, second, third and fourth wave was 1.4 ± 1.0, 6.9 ± 1.4, 11.6 ± 1.8 and 16.8 ± 1.6, respectively. No differences (P > 0.05) were found between the day of onset of the first and second waves for estrous cycles with three, four or five waves. However, the day of onset of the third and fourth waves occurred later when the number of waves per estrous cycle increased (P < 0.001). The duration of the interwave interval (time between the day of onset of two consecutive waves) was longer when the second wave was ovulatory. The length of the growth phase (2.4 ± 0.9 days) and size (5.9 ± 0.7 mm) of the dominant follicle in the second wave were lower (P < 0.01) than for the first wave (3.3 ± 1.2 days and 6.6 ± 0.9 mm, respectively) and the fifth wave (4.1 ± 1.2 days and 7.5 ± 1.0 mm, respectively). Within pairs of ovaries, the onset of the last wave occurred later (P < 0.05) and was less variable in ovulatory ovaries (day 16.8 ± 1.4, n = 20) than in anovulatory ovaries (day 15.1 ± 3.7, n = 20). The length of the growing phase was longer (P < 0.001) in the last waves of ovulatory ovaries (3.1 ± 0.9 days) than in the last waves of anovulatory ovaries (1.7 ± 0.8 days). These results support the hypothesis that the day of onset of the ovulatory wave is related to or, at least, conditioned by the luteolysis and the decrease in plasma progesterone. * Corresponding author. Tel.: +35 1259350417; fax: +35 1259350480. J. Simões et al. / Animal Reproduction Science 95 (2006) 16-26 17 In summary, the estrous cycle of Serrana goats is characterized by sequential follicular wave growth with a great variability in their onset and duration, with the exception of the ovulatory wave. The temporal and morphological differences observed in the last wave of estrous cycle provide strong evidence for the role of progesterone in their regulation.

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“…Despite a high proportion of ewes showing oestrus symptoms after the second dose, this occurs in a wide range of time, around 120 h (Loubser and van Niekerk 1981), which precludes its use in TAI. Ultrasonography studies have demonstrated that the variable response to PGF2 α treatments in cows (Kastelic and Ginther 1991) and ewes (Viñoles and Rubianes 1998) was related with the specific ovarian status of each animal at the time when PGF2 α was given. If a large healthy growing follicle is present at time of treatment, oestrus and ovulation will occur soon after PGF2 α administration.…”

Section: Introductionmentioning

confidence: 99%

Prostaglandin F2α Treatment Associated with Timed Artificial Insemination in Ewes

Menchaca

Miller

Gil³

et al. 2004

Reprod Domestic Animals

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Traditional treatments of two prostaglandin F2 alpha (PGF2alpha) doses at 10-day intervals or more did not result in acceptable pregnancy rates in timed artificial insemination (TAI) programmes in ewes. An explanation might be the undefined time-period of the onset of oestrus and ovulation after the treatment. Recently a consistent interval to oestrus and ovulation was obtained by giving PGF2alpha at day 3 post-ovulation, i.e. when the largest follicle of the first follicular wave of the cycle was still growing. This can be achieved when a second dose of PGF2alpha is given 7 days after a first dose. In this work, we evaluated the synchronization of oestrus and determined which of three different moments of TAI was the most successful using a PGF2alpha (PG-7d) protocol in a large flock. A total of 436 nulliparous and multiparous ewes were treated with two doses of a PGF2alpha analogue (delprostenate 160 microg, i.m.) separated by 7 days. Onset of oestrus was recorded twice a day and a single cervical TAI with fresh undiluted semen was performed either at 42 h (n = 152), 48 h (n = 120), or 54 h (n = 164), after the second PGF2alpha dose without taking into account the oestrous response. Pregnancy rate was determined by transrectal ultrasonography 30 days after insemination. Onset of oestrus was detected in 308 of 328 and 89 of 108 multiparous and nulliparous ewes, respectively (p < 0.001), within 72 h after treatment. The distribution of the onset of oestrus did not differ between multiparous and nulliparous ewes and the highest proportion of ewes in oestrus was detected between 25 to 48 h (313/397) from the second PGF2alpha dose. The pregnancy rate in ewes inseminated at 42 h tended to be higher than those inseminated at 48 h (p = 0.09) and was higher than those inseminated at 54 h (p < 0.05) (56/152, 31/120, 37/164; respectively). Therefore, the use of the PG-7d protocol resulted in a very high synchronization of oestrus with the highest concentration (around 80%) between 25 to 48 h from the end of treatment. The best pregnancy rate (37%) was obtained after a single cervical TAI with fresh semen at 42 h.

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Origin of the preovulatory follicle after induced luteolysis during the early luteal phase in ewes

Cited by 21 publications

References 8 publications

Timing of Preovulatory LH Surge and Ovulation in Superovulated Sheep are Affected by Follicular Status at Start of the FSH Treatment

Timing of Preovulatory LH Surge and Ovulation in Superovulated Sheep are Affected by Follicular Status at Start of the FSH Treatment

Follicular dynamics in Serrana goats

Prostaglandin F2α Treatment Associated with Timed Artificial Insemination in Ewes

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