Resumption of ovarian activity in post-partum ewes: Role of the uterus

Schirar, A.; Meusnier, Chantal; Paly, J.; Levasseur, Marie-Claire; Martinet, J.

doi:10.1016/0378-4320(89)90048-1

Cited by 16 publications

(12 citation statements)

References 17 publications

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“…Cognié, unpublished data). However, in the present work as well as in other studies in naturally ovulating ewes (Sharpe et al, 1986;Schirar et al, 1989) and cows (Hinshelwood et al, 1982) a higher incidence of abnormal luteal phases was observed in non-suckling than in suckling ewes. This finding, and the small delay (6 days) in the resumption of normal oestrous cycle, suggests that suckling, rather than delaying the return of potential fertility, primarily affects the conditions of this return by acting as a protective or a regulatory mechanism to ensure an harmonious post-partum resumption of ovarian activity.…”

Section: Discussioncontrasting

confidence: 50%

“…It has been well established that oestrus expression in the ewe requires the sequential action of progesterone and oestradiol (Robinson, 1954;Signoret, 1970 (1989) indicates that inadequate luteal function is specific to the peculiar physiological situation of the ewes early after lambing. Schirar et al (1989) have suggested that it might result from the luteolytic influence of the involuting uterus and an incomplete restoration of LH release leading to insuf¬ ficient follicle growth and maturation (R. J. Scaramuzzi & Y. Cognié, unpublished data).…”

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

Resumption of oestrous behaviour and cyclic ovarian activity in suckling and non-suckling ewes

Schirar

Cognie²,

Louault³

et al. 1989

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Section: Discussioncontrasting

confidence: 50%

Section: Discussionmentioning

confidence: 99%

Resumption of oestrous behaviour and cyclic ovarian activity in suckling and non-suckling ewes

Schirar

Cognie²,

Louault³

et al. 1989

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“…The present post-partum anoestrous interval was longer than reported in temperate ewes (Rhind et al, 1980;Schirar, Meusnier, Paly, Levasseur and Martinet, 1989). It is, however, important to emphasize that ewes were on natural pasture grazing with uncontrolled mating, and showed ovarian activity at all times of the year.…”

Section: Discussionmentioning

confidence: 46%

Resumption of post-partum oestrous behaviour and associated plasma progesterone profiles in Menz ewes

Mukasa-Mugerwa¹,

Ezaz²

1991

Anim. Sci.

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Fifty Ethiopian Menz ewes maintained on pasture grazing with uncontrolled mating showed ovarian cyclicity at all times of the year. Conception rates to first, second and third service were 78, 18 and 4%, respectively. Mean post-partum anoestrous interval was 76-1 (s.e. 4-6) days. Two-thirds of ewes conceived before lamb weaning at 90 days and had 8 month lambing intervals. Twice weekly progesterone determinations showed that 67% of ewes exhibited a silent ovulation 66-4 (s.e. 10-5) days post partum, 12% of oestrous cycles were longer than 20 days and 8% of heats were false or anovulatory. It was concluded that Menz ewes have the natural potential for three lambings in 2 years, under adequate nutrition. Their better management and genetic improvement should further reduce current lambing intervals and increase annual reproductive rates.

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“…Indeed, we have previously shown that the induction of ovulation during the post-partum period is associated with a high incidence of prematurely regressing corpora lutea which is independent of the suckling stimulus but dependent on the stage post par¬ tum (Wallace, Robinson & Aitken, 1989a;Wallace, Robinson, McKelvey & Aitken, 1989c). A large body of circumstantial evidence suggests that these prema¬ turely regressing corpora lutea result from enhanced or premature release of prostaglandin F2a (PGF2a) from the uterus (Troxel & Kesler, 1984; Copelin, Smith, Garverick & Youngquist, 1987;Lewis & Bolt, 1987;Copelin, Smith, Keisler & Garverick, 1989;Schirar, Meusnier, Paly et al 1989). …”

Section: Introductionmentioning

confidence: 98%

Characterization and autoradiographical localization of oxytocin receptors within the ovine endometrium in relation to post-partum corpus luteum function

Wallace¹,

Morgan²,

Helliwell³

et al. 1991

Journal of Endocrinology

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The induction of ovulation in early post-partum ewes is associated with a high incidence of premature luteal regression which is independent of the suckling stimulus but dependent on the stage post partum. The aim of the present study was to determine whether oxytocin receptors are present on uterine endometrium early in the luteal phase and hence ascertain whether oxytocin-induced uterine prostaglandin F2 alpha release is a possible mechanism involved in the premature regression of these post-partum corpora lutea. Ovarian and uterine tissues were collected on day 4 of the the cycle in ewes induced to ovulate at either 21 or 35 days post partum (n = 4 per group). A further four cyclic ewes were similarly synchronized to ovulate and acted as controls. Corpora lutea from the 21-day post-partum group were significantly (P less than 0.01) smaller, had a lower progesterone content and a reduced capacity to secrete progesterone in vitro than corpora lutea from 35-day post-partum or control ewes. A highly specific oxytocin receptor ligand 125I-labelled d(CH2)5[Tyr(Me)2, Thr4,Tyr-NH29]-vasotocin was used to localize and characterize high affinity oxytocin receptors in uterine endometrium (dissociation constant 145 pmol/l). Oxytocin receptor concentrations in endometrium from ewes induced to ovulate at 21 days post partum were on average five-fold higher (P less than 0.05) than in 35-day post-partum and control groups.

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Resumption of ovarian activity in post-partum ewes: Role of the uterus

Cited by 16 publications

References 17 publications

Resumption of oestrous behaviour and cyclic ovarian activity in suckling and non-suckling ewes

Resumption of oestrous behaviour and cyclic ovarian activity in suckling and non-suckling ewes

Resumption of post-partum oestrous behaviour and associated plasma progesterone profiles in Menz ewes

Characterization and autoradiographical localization of oxytocin receptors within the ovine endometrium in relation to post-partum corpus luteum function

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