Effects of exogenous steroid hormones on the dominant follicle maintained by a Norgestomet implant in heifers

Rajamahendran, R.; Manikkam, Mohan

doi:10.4141/cjas94-065

Cited by 24 publications

(9 citation statements)

References 36 publications

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“…Dominant follicles selected during early postpartum do not usually ovulate, yet can be stimulated to secrete more oestradiol using exogenous LH pulses, which will cause an oestradiol surge inducing the gonadotrophin surge and ovulation (Duffy et al 2000). Increased LH pulse frequencies seen following progestagen treatments will prolong the period of dominance of DFs (Savio et al 1993;Stock and Fortune, 1993;Mihm et al 1999), while atresia can be reliably caused in artifically maintained DFs by an acute decrease in LH pulse frequency using exogenous progesterone (Savio et al 1993;Rajamahendran and Manikkam 1994), GnRH antagonist (Manikkam et al 1995) or oestrogen (Yelich et al 1997). Dominant follicle atresia occurs with an associated decrease in intrafollicular oestradiol and free IGF-I, increases in lower molecular weight IGFBPs and granulosa cell apoptosis (de la Sota et al 1996;Stewart et al 1996;Manikkam and Rajmahendran 1997;Ginther et al 2001).…”

Section: Fsh and Dominant Folliclesmentioning

confidence: 99%

Follicle Wave Growth in Cattle

Mihm

Crowe

Knight

et al. 2002

Reprod Domestic Animals

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Ovarian follicle growth in cattle culminates in the selection of a single dominant follicle which attains the ability for final maturation and ovulation once or twice during the luteal phase and at the end of the oestrous cycle, as well as during other reproductive states. This review will describe in detail the first follicle wave of the cycle leading to selection of the first wave dominant follicle, indicating the specific gonadotrophin dependencies of cohort and dominant follicles, and relating follicle fate to steroidogenesis. As a differential gonadotrophin response of growing antral follicles during the follies-stimulating hormone (FSH) decline may determine which follicle becomes selected, first wave follicles are also characterized in relation to intrafollicular growth factors, which may modify the gonadotrophin response, such as inhibins and members of the insulin-like growth factor (IGF) family. Subsequently, the follicular control of the transient FSH rise and decline so crucial to dominant follicle selection will be discussed. It is concluded that successful hormonal manipulation of follicle wave growth and dominant follicle selection will depend on our detailed understanding of the gonadotrophin requirements of differentiating wave follicles.

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Section: Fsh and Dominant Folliclesmentioning

confidence: 99%

Follicle Wave Growth in Cattle

Mihm

Crowe

Knight

et al. 2002

Reprod Domestic Animals

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“…Conception rates are greater in cows that are administered progesterone than in cows not administered progesterone to induce regression of the persistent ovarian follicle (Anderson and Day, 1994). Injection of doses of progesterone as small as 150 mg induces atresia of persistent dominant ovarian follicles (Rajamahendran and Mannikkam, 1994). Recent data from our laboratory indicate that conception rates are similar in cows in which development of persistent ovarian follicles does not occur as a result of administration of a large dose of norgestomet and in cows in which persistent ovarian follicles develop and then are induced to regress .…”

Section: Control Of Development Of Persistent Ovarian Folliclesmentioning

confidence: 99%

Progestin and estrogen regulation of pulsatile LH release and development of persistent ovarian follicles in cattle.

Kinder

Kojima

Bergfeld

et al. 1996

Journal of Animal Science

171

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When doses of progestin used commercially are administered to synchronize the stage of the estrous cycle among bovine females, fertility is reduced compared with that of untreated controls. The reduced fertility that results from the use of progestin based estrus synchrony regimens is associated with the development of persistent ovarian follicles. Persistent ovarian follicles develop as a result of the greater frequency of LH pulses that occurs during the period of treatment with progestins. The greater release of LH pulses results in enhanced secretion of 17 beta-estradiol from persistent ovarian follicles. The greater frequency of LH release or the greater secretion of 17 beta-estradiol associated with development of persistent ovarian follicles probably contributes to the reduced fertility that occurs when progestins are used to synchronize stage of the estrous cycle.

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“…Recentemente, o estradiol tem sido reconhecido pela sua capacidade de induzir a atresia dos folículos ovarianos (BÓ et al, 1995;MANIKKAN, 1994), daí o seu potencial em reverter a fertilidade quando associado a tratamentos com progesterona que, por outro lado, promove o crescimento e a ovulação dos folículos envelhecidos (MIHM et al, 1994;SAVIO et al, 1993a;STOCK ;FORTUNE, 1993).…”

Section: Tratamentos Com Progestágeno/progesterona E Estradiolunclassified

Sincronização da ovulação com dispositivo intravaginal de progesterona (CIDR®) em novilhas Bos indicus, Bos indicus x Bos taurus e Bos taurus

Carvalho¹

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, pelo incentivo e apoio mas, muito além disso, pelo exemplo: o seu inesgotável interesse pela reprodução animal e a sua infinita paixão pelo ensino e pela pesquisa constituem-se em um paradigma a ser seguido por toda a comunidade científica.Ao Prof. Dr. Cláudio Alvarenga de Oliveira, Chefe do Departamento e Coordenador do Programa de Pós-Graduação em Reprodução Animal, pela oportunidade e pela amizade.Ao Prof. Dr. José Antônio Visintin -sempre afável e disposto a contribuir -, pelos esclarecimentos e sugestões. indicus (9,5 ± 0,5mm) do que nas cruzadas (12,3 ± 0,4mm) e B. taurus (11,6 ± 0,5mm). O tratamento com PGF no D0 aumentou (P<0,05) o diâmetro do FD (11,9 ± 0,4 x 10,5 ± 0,5mm). A taxa de crescimento do FD foi menor (P<0,05) nas novilhas B. indicus (0,9 ± 0,1mm/dia) do que nas novilhas cruzadas (1,2 ± 0,1mm/dia) e B. taurus (1,1 ± 0,1mm/dia). A taxa de crescimento foi maior (P<0,05) nas novilhas tratadas com PGF no D0 (1,2 ± 0,1 x 0,9 ± 0,1mm/dia). A taxa de ovulação foi menor (P<0,05) nas novilhas B. indicus (39,1 %) do que nas novilhas cruzadas (84,0 %) e B. taurus (72,7 %). Novilhas tratadas com PGF no D0 apresentaram maior (P<0,05) taxa de ovulação (78,8 x 54,0 %). O intervalo entre a retirada do dispositivo de P 4 (D8) e a ovulação foi maior (P<0,05) nas novilhas B. indicus (78,0 ± 2,3h) do que nas novilhas B. taurus (73,5 ± 1,0h). A concentração sérica de P 4 durante o tratamento (D0 a D8) diferiu (P<0,05) entre as novilhas B. indicus (5,4 ± 0,4ng/ml), B. taurus (3,3 ± 0,2ng/ml) e cruzadas (4,3 ± 0,3ng/ml). A concentração de P 4 foi menor (P<0,05) nas novilhas tratadas com PGF no D0 (3,3 ± 0,2 x 5,2 ± 0,3ng/ml ABSTRACTThis study evaluated the effect of treatment with progesterone intravaginal device (CIDR  ) associated to estradiol benzoate (BE) and prostaglandin F 2∝ in the follicular dynamic of B. indicus (Nelore and Gir), B. taurus (Angus and BWH) and respectively cross-breed. Aiming to evaluate the effect of different plasmatic progesterone concentration (P 4 ) in the follicular dynamic (3 by 2 factorial design), a half of heifers in each genetic group received PGF at moment of device insertion (D0). The ultrasonography was performed from D0 to D8 (device withdrawal) every 24 hours, and from D9 to ovulation every 12 hours to evaluate the follicular growth. All heifers were bled on D0, on D3, on D6, on D8 and on D10 for determination of serum progesterone concentration. The maximum diameter of DF was lower (P<0.05) in B. indicus heifers (9.5 ± 0.5mm) than in cross-breed (12.3 ± 0.4mm) and in B. taurus (11.6 ± 0.5mm) heifers. The PGF treatment on D0 increased (P<0.05) the diameter of DF (11.9 ± 0.4 x 10.5 ± 0.5mm). The growth rate of DF was lower (P<0.05) in B. indicus heifers (0.9 ± 0.1mm/day) than in cross-breed (1.2 ± 0.1mm/day) and in B. taurus (1.1 ± 0.1mm) heifers. The growth rate was higher (P<0.05) in heifers that received PGF on D0 (1.2 ± 0.1 x 0.9 ± 0.1mm/day). The ovulation rate was lower (P<0.05) in B. indicus heifers (39.1%) than in cross-breed (84.0%) and in B. taurus (72.7%). Heife...

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Effects of exogenous steroid hormones on the dominant follicle maintained by a Norgestomet implant in heifers

Cited by 24 publications

References 36 publications

Follicle Wave Growth in Cattle

Follicle Wave Growth in Cattle

Progestin and estrogen regulation of pulsatile LH release and development of persistent ovarian follicles in cattle.

Sincronização da ovulação com dispositivo intravaginal de progesterona (CIDR®) em novilhas Bos indicus, Bos indicus x Bos taurus e Bos taurus

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