Resumption of gonadotrophin release during the post-partum period in suckling and non-suckling ewes

Schirar, A.; Cognie, Y.; Louault, Florent; Poulin, Noëlle; Meusnier, Chantal; Levasseur, Marie-Claire; Martinet, J.

doi:10.1530/jrf.0.0880593

Cited by 36 publications

(16 citation statements)

References 14 publications

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“…In ewes, FSH secretion followed a quite clear wave-like pattern from the day after lambing that suggested a 4-6-day rhythm [37]. These findings are concomitant with earlier findings in cyclic goats [38] and indicated that the follicular waves occur regularly under conditions of basal LH and FSH during the postpartum period in the goat.…”

Section: Discussionsupporting

confidence: 86%

Follicular Turnover and Hormonal Association in Postpartum Goats During Early and Late Lactation

et al. 2012

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Abstract.To clarify the effect of lactation period on ovarian follicular activity and associated hormonal levels in goats, six goats were monitored daily by ultrasonographic examination with blood sampling during early (Days 5 to 25; Day 0 was the day of kidding) and late (Days 40 to 60) lactation. While the presence of a corpus luteum of pregnancy retarded follicular growth in the ipsilateral ovary until Days 11-13 postpartum, the total follicular number (TFN) and area (TFA) increased during late lactation due to the significant increase in the number of medium-and large-sized follicles and decrease in the number of small follicles. Four goats showed a similar pattern of follicular development during the period studied characterized by the emergence of five and six waves during the early and late lactation, respectively. The largest follicle diameter of the first three waves monitored during early lactation was significantly smaller as compared with the diameter of those existing during late lactation. TFN showed a positive correlation with FSH but showed a negative correlation with immunoreactive (ir-) inhibin and estradiol during the postpartum period. TFA was positively correlated with ir-inhibin, estradiol and PRL and negatively correlated with FSH during the monitored periods. The plasma levels of ir-inhibin and progesterone were significantly higher during late lactation compared with the levels recorded during early lactation. Ir-inhibin levels showed a significant positive correlation with LH and estradiol during early and late lactation but showed a negative correlation with FSH during the whole lactation period. LH was positively correlated with estradiol and PRL during early and late lactation, respectively. These results suggest that the lactation period has a detrimental effect on ovarian activity during the early postpartum period in goats. Key words: Goat, Gonadotropic hormones, Lactation, Ovary, Postpartum (J. Reprod. Dev. 58: 61-68 , 2012) T he understanding of ovarian follicular dynamics and its hormonal control in goats has increased in recent years due to the use of ultrasonography and provides information that is important for establishing improved methods to solve the problem of prolonged lactating anestrus in domestic animals [1]. Previous findings in other ruminants including the wave-like pattern of follicular growth, follicular dominance and the role of progesterone in follicular turnover, have been recently extended to the Caprine species [2]. Nevertheless, information regarding ovarian activity and the mechanisms regulating the postpartum anestrous period in goats is still scarce.Follicular activity resumed as early as Day 13 in the ovaries of postpartum goats, and medium-or large-sized follicles were present in the ovaries soon after [3]. Sosa [4] showed that the goat ovarian cyclicity resumed after complete uterine involution at the 5th week postpartum. In ewes, although follicles larger than 2 mm in diameter appeared as early as Day 5 postpartum [5], no follicles larger than 3 ...

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Section: Discussionsupporting

confidence: 86%

Follicular Turnover and Hormonal Association in Postpartum Goats During Early and Late Lactation

et al. 2012

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“…However, in our study, the elevated PRL levels did not decrease rapidly as in cows [4][5][6][7][8], and the elevated levels gradually decreased with time after parturition. These differences are thought to be derived from the stimulation of suckling by kids, since the suckling stimulates a PRL release in goats [6] and sheep [39]. In our experiment, the nursing goats were kept with their kids and allowed to be suckled freely throughout the experiment.…”

Section: Discussionmentioning

confidence: 99%

Plasma Profiles of Growth Hormone, Prolactin and Insulin-like Growth Factor-I during Gestation, Lactation and the Neonatal Period in Goats.

et al. 1999

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Abstract. The objectives of this research were to characterize plasma profiles of growth hormone (GH), prolactin (PRL) and insulin-like growth factor-I (IGF-I) during gestation and the lactation period in goats, as well as in their suckling growing kids. There were no obvious changes in the GH or PRL profiles during gestation, but secretion of both GH and PRL increased acutely after parturition. The elevated GH concentrations were maintained until 3 months after parturition, whereas the PRL concentrations decreased gradually after parturition. The elevated hormone concentrations are thought to be caused mainly by an increase in the secretory pulse amplitudes. In contrast to the GH and PRL profiles, the plasma IGF-I concentrations during late gestation were significantly higher than the post-parturition concentrations, and the IGF-I concentrations in late gestation decreased gradually until the day of parturition. The plasma GH, PRL and IGF-I concentrations in kids 1 week after birth were high, and concentrations of each hormone decreased thereafter. These results show that the increased secretory potencies of pituitary GH and PRL after parturition are caused mainly by an increase in the secretory pulse amplitudes and that plasma GH is inversely related to plasma IGF-I compared over gestation and the lactation period in goats. Key words: GH, PRL, IGF-I, Gestation, Lactation.(J. Reprod. Dev. 45: [273][274][275][276][277][278][279][280][281] 1999) G estation is a composite of integrated processes, resulting in the successful development of fetuses and the birth of offspring. The energy and nutrient requirements in pregnant animals are increased during gestation [1]. The survival of newborn animals is dependent on an adequate supply of milk secreted from the mammary glands of the mother after parturition [2]. Since growth hormone (GH) regulates many aspects of metabolic activity [3], it is meaningful to examine the GH profiles throughout gestation and during the lactation period in animals. Plasma or serum concentrations of GH and prolactin (PRL) in ruminants have been observed to elevate acutely during the periparturient period [4][5][6][7][8][9]. In these published observations, however, blood samples were usually collected for only a few weeks around parturition, and plasma profiles of GH and PRL have never been examined throughout gestation. Moreover, the blood samples were collected only about once a day, although GH and PRL are known to be secreted in transient pulses [3,[10][11][12][13][14]. PRL is required for the initiation of lactation [15,16]; therefore, it is of interest to determine how the pulsatile secretory patterns of both GH and PRL change throughout gestation and during the lactation period in animals. The anabolic action of GH is

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“…On the other hand, it has been suggested that high concentrations of circulating progesterone and estradiol in pregnant ewes inhibited GnRH secretion in the hypothalamus [19]. However, ewes have been known to show recovery in the pulsatile secretion of GnRH within 3 weeks after lambing followed by the increase in the estradiol receptor in the hypothalamus and adenohypophysis when she lambed in the early breeding season [9,20]. These physiological changes in postpartum ewes lead to the resumption of subsequent estrous cyclicity.…”

Section: Discussionmentioning

confidence: 99%

“…Many studies in the mid-latitude regions have indicated that the resumption of the breeding season for non-lactating ewes administered melatonin occurred earlier than that in control ewes. On the other hand, it has been suggested that length of postpartum anestrus was affected by the lambing season, lactation and nutrition [7][8][9]. If early postpartum ewes…”

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confidence: 99%

Effect of Melatonin Feeding on Early Onset of Reproductive Activity in Postpartum Suffolk Ewes Lactating during Anestrous Season.

Kusakari¹,

Ohara²

1997

Journal of Reproduction and Development

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Abstract. Seasonally or postpartum anestrous Suffolk ewes were divided into the following 4 groups: Groups 1 (barren, n=5), 2 (postpartum/non-lactating, n=5) and 3 (postpartum/lactating, n=5) ewes were fed 4 mg melatonin daily for 60 days from 26 June (Day 1), and control ewes in Group 4 (postpartum/lactating, n=3) were fed vehicle pellets not containing melatonin. The plasma concentration of progesterone was monitored to assess the resumption of ovulatory cyclicity. The ewes were teased by a vasectomized ram daily on Day 4 onward, and introduced to fertile rams on Day 41. The resumption of ovulatory cyclicity in postpartum ewes fed melatonin were significantly earlier than that in postpartum ewes in the control (p<0.05). However, there was no difference in the timing of the onset of ovulatory cyclicity and return to estrus between non-lactating and lactating ewes treated with melatonin. The interval from the start of melatonin feeding to the onset of ovulatory cyclicity in postpartum ewes was longer than that in barren ewes (p<0.05). These results suggest that the physiological status in early postpartum ewes results in a delay of the reproductive response to melatonin administration mimicking the short-day pattern, but that the lactational suppression of gonadal function could be overcome by the melatonin treatment.

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Resumption of gonadotrophin release during the post-partum period in suckling and non-suckling ewes

Abstract: Summary. The post-partum secretion of LH, FSH and

Cited by 36 publications

References 14 publications

Follicular Turnover and Hormonal Association in Postpartum Goats During Early and Late Lactation

Follicular Turnover and Hormonal Association in Postpartum Goats During Early and Late Lactation

Plasma Profiles of Growth Hormone, Prolactin and Insulin-like Growth Factor-I during Gestation, Lactation and the Neonatal Period in Goats.

Effect of Melatonin Feeding on Early Onset of Reproductive Activity in Postpartum Suffolk Ewes Lactating during Anestrous Season.

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