Follicular activity and ovulation regulated by exogenous progestagen and PMSG in anestrous ewes

Leyva, Víctor; Buckrell, B.C.; Walton, J.S.

doi:10.1016/s0093-691x(98)00147-2

Cited by 40 publications

(30 citation statements)

References 55 publications

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“…In cyclic ewes treated with progestagens, prolongation of the lifespan of ovulatory follicles has been associated with the advancement of follicle emergence (Vinoles et al 2001), whereas this was related to both the advancement of follicle emergence and a delay in ovulation during seasonal anoestrus (Leyva et al 1998, Ungerfeld & Rubianes 1999. According to these reports, the longer growth and lifespan of preovulatory follicles in the ewes treated with progesterone were mainly related to a decreased growth rate and led to delayed LH surge and ovulation in our experiments.…”

Section: Discussionsupporting

confidence: 51%

Progesterone improves the maturation of male-induced preovulatory follicles in anoestrous ewes

Adib¹,

Fréret²,

Touzé³

et al. 2014

Reproduction

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The first ovulation induced by male effect in sheep during seasonal anoestrus usually results in the development of a short cycle that can be avoided by progesterone priming before ram introduction. In elucidating the involvement of the hypothalamic-pituitary-gonadal axis in the occurrence of short cycles, the effects of progesterone and the time of anoestrus on the development of male-induced preovulatory follicles were investigated in anoestrous ewes using morphological, endocrine and molecular approaches. Ewes were primed with progesterone for 2 (CIDR2) or 12 days (CIDR12) and untreated ewes used as controls during early (April) and late (June) anoestrus. The duration of follicular growth and the lifespan of the male-induced preovulatory follicles were prolonged by w1.6 days in CIDR12 ewes compared with the controls. These changes were accompanied by a delay in the preovulatory LH and FSH surges and ovulation. Intrafollicular oestradiol concentration and mRNA levels of LHCGR and STAR in the granulosa and theca cells of the preovulatory follicles were higher in CIDR12 ewes than the control ewes. The expression of mRNA levels of CYP11A1 and CYP17A1 also increased in theca cells of CIDR12 ewes. CIDR2 ewes gave intermediate results. Moreover, ewes ovulated earlier in June than in April, without changes in the duration of follicular growth, but these effects were unrelated to the lifespan of corpus luteum. Our results give the first evidence supporting the positive effect of progesterone priming on the completion of growth and maturation of preovulatory follicles induced by male effect in seasonal anoestrous ewes, thereby preventing short cycles.

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Section: Discussionsupporting

confidence: 51%

Progesterone improves the maturation of male-induced preovulatory follicles in anoestrous ewes

Adib¹,

Fréret²,

Touzé³

et al. 2014

Reproduction

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“…However, also the White Alpine Sheep kept in flocks B and C had a greater litter size than reported in earlier studies. In the present study, eCG was used to enhance the recruitment of small follicles (Noel et al, 1994), increase ovulation rates (Boland et al, 1981;Noel et al;, Leyva et al, 1998a and improve the synchrony of estrus (Boland et al, 1981;Cline et al, 2001) and may be the reason for the high prolificacy observed to the first service period. P4 concentrations were determined at insert application to confirm cyclicity, at insert removal to detect subluteal progesterone values in ewes treated with Eazi-breed™ CIDR ® G and 14 days later to verify ovulation.…”

Section: Discussionmentioning

confidence: 90%

Comparison of 6-day progestagen treatment with Chronogest® CR and Eazi-breed™ CIDR® G intravaginal inserts for estrus synchronization in cyclic ewes

Fleisch¹,

Werne²,

Heckendorn³

et al. 2012

Small Ruminant Research

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The aim of this study was to compare the efficacy of two different short-term progestagen treatments for estrus synchronization in cyclic ewes. A total of 292 ewes of 3 flocks (A-C) on different farms were treated for 6 days with Eazi-breed™ CIDR® G (n = 145) or Chronogest® CR (n = 147) vaginal inserts in combination with 0.125 mg Cloprostenol and 300IU eCG at device removal. Blood samples were taken for progesterone (P4) determination at insert application and removal as well as 14 days later. One day after insert removal rams fitted with marking harnesses were joined to ewes for 35 days and marked ewes recorded daily. Lambing data were recorded and fertility to first service period and overall assessed. Results show that 24-96 h after insert removal 98.8% and 89.4% of the synchronized ewes in the flocks B and C were in estrus. Estrus response was not affected by the type of progestagen treatment and was lower (P < 0.05) in nulli-(82.1%) than in pluriparous (97.5%) ewes. Type of progestagen treatment did not affect fertility, but flock and parity influenced the percentage of ewes that lambed as well as the lambing rate. Overall more ewes (P < 0.001) lambed in flock A compared to flocks B and C (93.0 vs. 72.5 and 59.1%). In nulliparous animals the percentage of ewes that lambed was higher to the first service (P < 0.05) period but lower (P < 0.001) to the overall service period compared to pluriparous animals (51.5% vs. 49.3% and 64.7% vs. 84.2%). Lambing rates were higher in flock A than in flocks B and C to first service period and overall (1.3 ± 1.4, 0.9 ± 1.0, and 0.7 ± 1.0, P < 0.01 and 1.9 ± 1.1, 1.3 ± 0.9, and 1.0 ± 1.0, P < 0.001) and in nulliparous overall lower than in pluriparous ewes (1.1 ± 1.1 and 1.6 ± 1.1, P < 0.01). Serum P4 concentrations measured 14 days after insert removal were higher in the Chronogest® CR than in the Eazi-breed™ CIDR® G group (6.8 ± 4.1 ng/mL vs. 5.7 ± 3.3 ng/mL). Ewes of flock A had higher P4 values compared to ewes of flocks B and C (8.3 ± 4.1 ng/mL vs. 4.5 ± 1.5 ng/mL and 3.8 ± 1.7 ng/mL) and nulliparous lower P4 concentrations than pluriparous ewes (4.5 ± 2.2 ng/mL vs. 6.7 ± 4.0 ng/mL). In conclusion, a 6-day treatment with Chronogest® CR and Eazi-breed™ CIDR® G with prostaglandin and eCG at insert removal resulted in high estrus response and similar fertility in cyclic ewes. AbstractThe aim of this study was to compare the efficacy of two different short-term progestagen treatments for estrus synchronization in cyclic ewes. A total of 292 ewes 72.5 and 59.1%). In nulliparous animals the percentage of ewes that lambed was higher to the first service (P<0.05) period but lower (P<0.001) to the overall service period compared to pluriparous animals (51.5 vs. 49.3% and 64.7 vs. 84.2%).Lambing rates were higher in flock A than in flocks B and C to first service period and overall (1.3±1.4, 0.9±1.0, 0.7±1.0, P<0.01 and 1.9±1

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“…This observation is surprising because the ewes treated with progestagens also received 500 IU eCG at sponge removal. Treatment with eCG is known to enhance the recruitment of small follicles [28], to improve the synchrony of estrus [29,30], to increase ovulation rates during the breeding season [28,29,31], and to enable the induction of estrous activity during the anovulatory season [32]. In this study, lambing rates (1.8-1.9) and litter sizes (1.9-2.0) were higher than those reported in previous investigations (0.7-1.1 and 1.1-1.7, respectively) [20,27,33].…”

Section: Discussionmentioning

confidence: 99%

Reproductive performance of Lacaune dairy sheep exposed to artificial long days followed by natural photoperiod without and with additional progestagen treatment during the nonbreeding season

et al. 2015

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This study compared the reproductive performance of Lacaune dairy ewes exposed to a light program and subsequent male introduction without (n = 36) or with (n = 36) an additional 6-day progestagen treatment during the nonbreeding season. All ewes were exposed to extended day length (16 hours light and 8 hours darkness) for 77 days during winter (December 15 until March 2) followed by increasing natural photoperiod. At the end of the photoperiodic treatment, three blood samples were collected 6 days apart for progesterone (P4) analysis to determine cyclic activity. One half of the ewes were additionally subjected to a 6-day progestagen treatment in combination with PGF2 and eCG at insert withdrawal. Rams fitted with marking harnesses were introduced to females for 45 days and marked ewes recorded. Ewes exposed to the light program only were joined 40 days after the end of photoperiodic treatment, and ewes with additional progestagen treatment were joined 1 day after insert removal (40-44 days after the end of photostimulation). Lambing data were recorded and fertility (percentage of ewes lambing, lambing rate, and litter size) assessed to the first service period and overall. Mean serum P4 concentrations were similarly (P > 0.05) low in both groups (0.4-0.7 ng/mL vs. 0.4-0.6 ng/mL). On the basis of elevated P4 levels (>1 ng/mL), evidence of luteal activity was found in 27.8% of the ewes at the end of the light program. Estrus response was equally high (97.2%) and estrus distribution highly synchronized in progestagen-treated ewes (91.7% within 4 days). In ewes exposed to the light program only, estrous activity was recorded within 4 days (six ewes), from Day 8 to Day 17 (17 ewes) and from Day 19 to Day 25 (12 ewes) after joining. The percentage of ewes that lambed to the first service period was higher (P < 0.05) in ewes exposed to the light program only than that in the group additionally treated with progestagen/PGF2 /eCG (94.4% vs. 69.4%). Overall, the percentage of lambing ewes was similar in both groups (97.2% and 94.4%), and lambing rates (1.4-1.9) and litter sizes (1.9-2.1) were high and not influenced (P > 0.05) by the treatment. In conclusion, this study reports that exposition of Lacaune ewes to artificial long days followed by natural day length and male introduction is highly effective to induce fertile estrous activity during the nonbreeding season and offers a reliable and practical alternative to hormonal manipulation for out-of-season breeding in sheep. a b s t r a c tThis study compared the reproductive performance of Lacaune dairy ewes exposed to a light program and subsequent male introduction without (n ¼ 36) or with (n ¼ 36) an additional 6-day progestagen treatment during the nonbreeding season. All ewes were exposed to extended day length (16 hours light and 8 hours darkness) for 77 days during winter (December 15 until March 2) followed by increasing natural photoperiod. At the end of the photoperiodic treatment, three blood samples were collected 6 days apart for progesterone (...

show abstract

Follicular activity and ovulation regulated by exogenous progestagen and PMSG in anestrous ewes

Cited by 40 publications

References 55 publications

Progesterone improves the maturation of male-induced preovulatory follicles in anoestrous ewes

Progesterone improves the maturation of male-induced preovulatory follicles in anoestrous ewes

Comparison of 6-day progestagen treatment with Chronogest® CR and Eazi-breed™ CIDR® G intravaginal inserts for estrus synchronization in cyclic ewes

Reproductive performance of Lacaune dairy sheep exposed to artificial long days followed by natural photoperiod without and with additional progestagen treatment during the nonbreeding season

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