Effet de la progestérone sur le taux d'ovulation et la durée du cycle ovarien induits par effet mâle chez la brebis Barbarine et la chèvre locale tunisienne

Lassoued, N.; Khaldi, G.; Cognie, Y.; Chemineau, Philippe; Thimonier, J.

doi:10.1051/rnd:19950406

Cited by 23 publications

(14 citation statements)

References 12 publications

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“…However, in sheep and cattle, the intra-uterine administration of indomethacin prevents luteal regression (Lewis and Warren, 1977) and decreases PGFM in the plasma (Troxel and Kesler, 1984 (Southee et al, 1988) and at different moments after ovulation induction (Sankot and Murdoch, 1991 (Bensadoun and Reid, 1962). However, this is unlikely as when one administers intramuscularly 20 mg progesterone to hysterectomized ewes, the elimination of the hormone is slower (4 days, fig 3c) than in intact ewes (1 day, Lassoued et al, 1995 (Hunter et al, 1989). Progestagen treatment inhibits the establishment of oxytocin receptors and the release of prostaglandins in response to oxytocin administration (Vallet et al, 1990 (Rubianes et al, 1996) and probably reduces the increase in E2 secretion observed by Mattner and Braden (1972).…”

Section: Methodsmentioning

confidence: 99%

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Role of the uterus in early regression of corpora lutea induced by the ram effect in seasonally anoestrous Barbarine ewes

Lassoued¹,

Khaldi²,

Chemineau³

et al. 1997

Reprod. Nutr. Dev.

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Summary -The involvement of the uterus in early regression of corpora lutea induced by the ram effect was studied in seasonally anoestrous Barbarine ewes. In experiment 1, group I was only submitted to the male effect (control, n = 15) while group II (n = 14) was injected every 12 h with flunixin meglumine, a PGF2a synthetase inhibitor (finadyne), from day 3 to day 6 (day 0: day of ram introduction). The preovulatory LH surge appeared at the same time (around 21 h after ram introduction) in both groups. Finadyne treatment significantly decreased 13-14-dihydro-15-keto-PGF2a (PGFM) pulses ( 1.3 ± 0.3 versus 0.4 ± 0.2; P < 0.05), the number of short cycles (50 versus 14%, P < 0.05), and provided a single peak of oestrus, 15-16 days after the introduction of the rams, instead of between day 14 and day 23 (P < 0.01 In experiment 2, 17 hysterectomized ewes were allocated into two groups: group III (n = 8) was injected with oil and group IV (n = 9) received an intramuscular injection of 20 mg of progesterone immediately before introduction of rams. An additional group of intact ewes was used as control (group V, n = 9). Hysterectomy did not affect the ovulation response to the ram effect, but completely suppressed short cycles (0 versus 78% , P < 0.001). The preovulatory LH surge was delayed in hysterectomized females (36.0 ± 14.1 versus 16.6 ± 11.4 h; P < 0.004). Treatment with progesterone significantly (P < 0.01) increased the interval between introduction of rams and the preovulatory LH surge. In conclusion, suppression of short cycles by hysterectomy and an inhibitor of PGF2a synthetase suggest that the uterus is essential for determining the lifespan of ram-induced corpora lutea and that premature release of PGF2a is the cause of early luteal regression. The hypothesis that lower secretion of progesterone before D5 could be the initial cause of the premature induction of the luteolytic signal is discussed.

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Section: Methodsmentioning

confidence: 99%

“…In all cases, the length of these cycles is less than 7 days (Oldham, 1980;Knight et al, 1981;Chemineau, 1983;Southee et al, 1988; Lassoued and Khaldi, 1993;Lassoued et al, 1995).…”

Section: Introductionmentioning

confidence: 99%

Role of the uterus in early regression of corpora lutea induced by the ram effect in seasonally anoestrous Barbarine ewes

Lassoued¹,

Khaldi²,

Chemineau³

et al. 1997

Reprod. Nutr. Dev.

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“…This provokes an important delay in the post-introduction events: LH surge and subsequent ovulations are delayed from 24 to 72 h, depending on the experiments [5,17,56,57]. This was also demonstrated in goats [58,59]. The concomitant suppression of short-lifespan CL and of enlargement of the interval, introduction of male-LH preovulatory surge, led to the proposition that the existence of these short-lifespan CL is due to an insufficient follicle maturation before ovulation [57].…”

Section: How Exogenous P4 Acts To Completely Suppress Short Cycles? Imentioning

confidence: 97%

Male-induced short oestrous and ovarian cycles in sheep and goats: a working hypothesis

et al. 2006

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-The existence of short ovulatory cycles (5-day duration) after the first male-induced ovulations in anovulatory ewes and goats, associated or not with the appearance of oestrous behaviour, is the origin of the two-peak abnormal distribution of parturitions after the "male effect". We propose here a working hypothesis to explain the presence of these short cycles. The male-effect is efficient during anoestrus, when follicles contain granulosa cells of lower quality than during the breeding season. They generate corpora lutea (CL) with a lower proportion of large luteal cells compared to small cells, which secrete less progesterone, compared to what is observed in the breeding season cycle. This is probably not sufficient to block prostaglandin synthesis in the endometrial cells of the uterus at the time when the responsiveness to prostaglandins of the new-formed CL is initiated and, in parallel, to centrally reduce LH pulsatility. This LH pulsatility stimulates a new wave of follicles secreting oestradiol which, in turn, stimulates prostaglandin synthesis and provokes luteolysis and new ovulation(s). The occurrence of a new follicular wave on days 3-4 of the first male-induced cycle and the initiation of the responsiveness to prostaglandins of the CL from day 3 of the oestrous cycle are probably the key elements which ensure such regularity in the duration of the short cycles. Exogenous progesterone injection suppresses short cycles, probably not by delaying ovulation time, but rather by blocking prostaglandin synthesis, thus impairing luteolysis. The existence, or not, of oestrous behaviour associated to these ovulatory events mainly varies with species: ewes, compared to does, require a more intense endogenous progesterone priming; only ovulations preceded by normal cycles are associated with oestrous behaviour. Thus, the precise and delicate mechanism underlying the existence of short ovulatory and oestrous cycles induced by the male effect appears to be dependent on the various levels of the hypothalamo-pituitary-ovario-uterine axis.male-effect / ovulation / corpus luteum / cycle / oestrus / uterus

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“…Furthermore, short ovarian cycles result in scattered lambing because estrouses occur 18-21 and 24-27 days after introduction of rams. A pretreatment with 20 mg of progesterone (P4) on the day of ram introduction or 3 d before prevents short cycles, so that the first silent ovulation is followed by a normal cycle, with a single peak of estrus 18-21 days after the introduction of rams [6][7][8][9][10]. Estrus behaviour occurs at the first induced ovulation if ewes are treated with progestagen, such as fluorogestone acetate (FGA), using subcutaneous implants or intravaginal sponges [6,11].…”

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confidence: 99%

Progesterone Plus PMSG Priming in Seasonally Anovulatory Lactating Sarda Ewes Exposed to the Ram Effect

Todini

Malfatti

Barbato

et al. 2007

Journal of Reproduction and Development

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Abstract. The aim of this trial was to evaluate the effectiveness (fertility and lambing) of priming with a single injection of progesterone plus PMSG in anovulatory lactating Sarda ewes subjected to the ram effect (RE) in spring. Thirty ewes (P4 group) were i.m. injected with 30 mg progesterone and 500 IU PMSG 36 h before ram introduction (d 0). This treatment was compared to a 12-day treatment with fluorogestone acetate intravaginal sponges that was followed by injections of 350 IU PMSG upon sponge withdrawal (FGA group, n=30). All ewes responded to RE, showing plasma progestrone concentrations >1 ng/mL between d 6 and 12 (FGA) or 6 and 9 (P4). Eighty-nine percent of the P4 ewes conceived at first ovulation, and 11% conceived following a short estrus cycle. Lambings occurred on d 150.4 ± 3.9, and the lambing rate was 100%. The fertility of the FGA ewes was 83% for the induced ovulation and was 7% for the second ovulation after a normal cycle. The FGA ewes lambed on d 149.8 ± 4.4, and the lambing rate was 83%. Two abortions were recorded for the FGA ewes, which had higher prolificacy than the P4 group (2.2 ± 0.8 vs. 1.8 ± 0.4, respectively; P<0.05). Both fertility and the lambing rate were high in both groups, with a high degree of estrus synchronization, and there were no significant differences between the groups. We concluded that priming of lactating Sarda ewes in spring with P4+PMSG before RE is an effective and competitive method (cheaper and more practical than FGA+PMSG) of inducing fertile ovulations in these ewes. Key words: Estrus induction, Fertility, Progesterone priming, Prolificacy, Sheep (J. Reprod. Dev. 53: [437][438][439][440][441] 2007) h e " r a m e f f e c t " ( R E ) i s a n a t u r a l a n d i n e x p e n s i v e m e t h o d f o r c o n t r o l o f t h e reproductive activity in sheep [1]. The sudden introduction of rams to seasonally anovulatory ewes induces ovulations without estrus within 2 to 4 days. This silent ovulation is followed by either an ovarian cycle of normal duration (16-17 days) and a second ovulation associated with estrus behaviour or by an ovarian cycle of short duration (6 days) followed by a second silent ovulation. In this latter case, ovulation and estrus occur after a cycle of normal duration [2,3]. With "deep" anoestrous the percentage of short cycles is high, and anoestrus can follow the induced ovulations. The "depth" of anoestrus for a given flock in a given period could be measured as the percentage of females spontaneously ovulating, and it determines a wide range of variations in female responsiveness to RE [4]. RE is very effective in the Merinos and Mediterranean breeds of ewes, which show a shorter anoestrus period that is less deep

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Effet de la progestérone sur le taux d'ovulation et la durée du cycle ovarien induits par effet mâle chez la brebis Barbarine et la chèvre locale tunisienne

Cited by 23 publications

References 12 publications

Role of the uterus in early regression of corpora lutea induced by the ram effect in seasonally anoestrous Barbarine ewes

Role of the uterus in early regression of corpora lutea induced by the ram effect in seasonally anoestrous Barbarine ewes

Male-induced short oestrous and ovarian cycles in sheep and goats: a working hypothesis

Progesterone Plus PMSG Priming in Seasonally Anovulatory Lactating Sarda Ewes Exposed to the Ram Effect

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