Seasonal changes in ovarian activity: Lessons learnt from the horse

Donadeu, F.X.; Watson, E.D.

doi:10.1016/j.anireprosci.2006.12.001

Cited by 53 publications

(42 citation statements)

References 73 publications

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“…IGF1R expression increased with follicle size during the ovulatory period but not during the transitional period, and this resulted in higher expression levels in 25-34 mm follicles during the ovulatory period than during the transitional period but similar levels in 15-24 mm follicles between the two periods. This result is consistent with the essential role of IGF1 in the selection and subsequent development of ovulatory follicles (reviewed in Beg & Ginther 2006) and also with the causative role of deficient IGF1 stimulation in the failure of transitional follicles to develop characteristics of ovulatory follicles (reviewed in Donadeu & Watson 2007). The present results in mares are in contrast to some of the previous studies in which IGF1R expression in granulosa cells did not change (Armstrong et al 2000, Liu et al 2000, Hastie & Haresign 2006, Llewellyn et al 2007 or decreased (Perks et al 1995) during growth of antral follicles in cows and pigs or between seasons in sheep.…”

Section: Discussionsupporting

confidence: 69%

“…Since IGF1 is known to stimulate steroidogenesis in vitro (Glister et al 2001) and there is a temporal association between reduced IGF1 activity and low oestradiol levels during transition (reviewed in Donadeu & Watson 2007), we wished to examine whether experimentally increasing intrafollicular IGF1 activity before the beginning of deviation during the transitional period would lead to an stimulation of oestradiol production. The absence of an oestradiol response to IGF1 in that regard is similar to results after intrafollicular IGF1 injection before the beginning of deviation in ovulatory mares (Ginther et al 2004c(Ginther et al , 2005 and is consistent with results in vitro showing that the ability of granulosa cells to respond with an increase in oestradiol may depend on the size of the follicles .…”

Section: Discussionmentioning

confidence: 99%

“…The period of spring transition between the anovulatory season and the ovulatory season in the mare is characterised by renewed follicular growth (reviewed in Donadeu & Watson 2007). During this period, follicular waves occur that can sequentially produce several large, anovulatory follicles usually in association with irregular periods of oestrus.…”

Section: Introductionmentioning

confidence: 99%

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Seasonal effects on the response of ovarian follicles to IGF1 in mares

Doyle

Hogg²,

Watson³

et al. 2008

Reproduction

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The response of follicles to IGF1 was compared between the transition into the ovulatory season (transitional period) and the ovulatory season (ovulatory period) in eight mares using a cross-over experimental design within periods. Granulosa cells were collected from follicles 15-24 or 25-34 mm and expression of IGF1R, IGF2R, FSHR, LHCGR and PAPPA was determined by qPCR. In addition, 10 mg IGF1 or vehicle were injected into the largest follicle (transitional period) or the second largest follicle (ovulatory period) of a follicular wave before the beginning of diameter deviation between the two largest follicles (mean diameters at injection 19.2 and 20.0 mm during transitional and ovulatory periods respectively). Follicular fluid was collected 24 h after injection for determination of free IGF1, IGFBP, inhibin A and oestradiol levels. Granulosa cells from follicles 25-34 mm, but not follicles 15-24 mm, expressed higher levels of IGF1R (PZ0.01), FSHR (P!0.007) and LHCGR (PZ0.09) during the ovulatory period than during the transitional period, whereas IGF2R expression was higher in transitional than ovulatory follicles (PZ0.06). Follicular IGFBP2 levels were not different (PO0.1) between periods and treatments, whereas IGFBP5 levels were higher (P!0.05) during the ovulatory period. Finally, IGF1 injection before the beginning of deviation induced an approximately twofold increase (PZ0.01) in follicular inhibin A levels during each period and did not affect oestradiol (PO0.1). These results suggest that, as during ovulatory waves, equine follicles during transitional waves are responsive to IGF1 before the beginning of deviation and that, therefore, inadequate IGF1 responsiveness before deviation may not underlie the deficient development of dominant follicles during transition. Reproduction (2008) 136 589-598

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Section: Discussionsupporting

confidence: 69%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Seasonal effects on the response of ovarian follicles to IGF1 in mares

Doyle

Hogg²,

Watson³

et al. 2008

Reproduction

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“…Existem muitas razões pelas quais se faz necessário a busca de novos métodos para que as éguas possam entrar em estro e obter um potro o mais próximo possível do início do ano hípico, sendo a principal, a adequação do nascimento dos produtos à data oficial imposta para cavalos de performance (DONADEU; WATSON, 2007). Nesse contexto, o Brasil é referência em estudo e utilização de biotécnicas de reprodução assistida nesses animais (OLIVEIRA FILHO et al, 2012).…”

Section: Introductionunclassified

Comportamento De Éguas Após a Inserção De Dispositivo Intravaginal Impregnado Com Progesterona

Martinez

Colli

Carvalho

et al. 2017

ArqVet

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Umuarama, v. 19, n. 3, p. 143-146, jul./set. 2016.RESUMO: Considerando a escassez de estudos sobre o temperamento ou reatividade de equinos, objetivou-se com esse estudo avaliar o comportamento de éguas após a inserção do implante intravaginal de progesterona, para utilização em bovinos, por meio da observação de comportamentos individuais e coletivos. Para tanto, utilizou-se sete éguas que receberam dispositivo intravaginal impregnado com progesterona e agente luteolítico. Após a colocação dos implantes e soltura das éguas, se iniciou a observação (cinco observadores sem contato entre eles) de seus comportamentos até o tempo de 120 minutos, seguindo o modelo proposto por Heleski et al. (2002). Os resultados indicaram que durante os 120 minutos de observação todas as éguas demonstraram estar alertas, pelo menos em uma observação; que o ato de comer foi observado em todos os animais durante o período estudado e que o ato de urinar e defecar foram observados, em aproximadamente, 70 e 60%, respectivamente, dos comportamentos avaliados. Comportamentos prováveis da indicação de dor e/ou desconforto, como bater da cauda, mímica de urinar, eversão do clitóris e urinando foram observados até 65 minutos, sendo que os três primeiros cessaram aos 55 minutos. De todos os comportamentos analisados, nenhum deles foi visualizado após 65 minutos de observação. Concluiu-se que a inserção do dispositivo intravaginal impregnado com progesterona não afeta negativamente o comportamento de éguas, podendo ser utilizado sem comprometer o bem-estar desses animais. PALAVRAS-CHAVE: Equino. Temperamento. Reatividade. Sincronização de estro. BEHAVIOR OF MARES AFTER INSERTION OF INTRAVAGINAL PROGESTERONE DEVICEABSTRACT: Considering the scarcity of studies on the behavior or reactivity of horses, this study aimed to assess the behavior of mares after insertion of intravaginal progesterone implant for use in cattle, through the observation of individual and collective behavior. In order to do so, seven mares received intravaginal devices impregnated with progesterone and luteolitic agent. After the implant was placed, the mares were released, and their behavior was observed (five observers with no contact between them) for a period of 120 minutes, following the model proposed by Heleski et al. (2002). The results indicated that during the 120-minute period, all mares were alert, in at least one observation; that all animals ate during the study period, and urination and defecation were observed in approximately 70 and 60%, respectively, of the assessed behavior. Behaviors that were likely an indication of pain and/or discomfort, like hitting the tail, miming to urinate, eversion of the clitoris and urinating were observed in up to 65 minutes, with the first three symptoms ceasing after 55 minutes. None of the analyzed behaviors were viewed after 65 minutes of observation. It can be concluded that the insertion of the intravaginal device impregnated with progesterone does not adversely affect the behavior of mares, and therefore, it can be use...

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“…During anestrus when GnRH is low, LH is at basal level, while FSH does not change dramatically throughout the year (Thompson Jr. et al 1986). Although other factors, both systemic and local at the ovarian level, appear to be involved in the onset of anestrus and the resurgence of cyclicity, many questions remain unanswered, as reviewed (Donadeu and Watson 2007).…”

Section: Anestrus and Transitionmentioning

confidence: 99%

A clinical view of mare reproductive physiology

Paccamonti¹,

Lyle²

2010

PHK

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SummaryAn understanding of clinically relevant aspects of equine reproductive physiology is helpful to the stud farm practitioner. Anestrus and transition can delay the desired onset of the breeding season and reduce the number of opportunities to establish pregnancy during the season. Although alteration of the photoperiod has long been accepted as the best way to advance the breeding season, recent research may provide additional assistance for hastening the onset of cyclicity. During the breeding season, knowing the pattern of ovulation in mares, both in general and for a particular mare, can be very beneficial in timing insemination for optimum conception rates. Likewise, appreciating the effects of luteolytic agents on aspects of reproductive physiology other than regression of the corpus luteum, such as on follicular development, ovulation, and development of hemorrhagic anovulatory follicles, can assist the clinician in improving breeding efficiency in mares.

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Seasonal changes in ovarian activity: Lessons learnt from the horse

Cited by 53 publications

References 73 publications

Seasonal effects on the response of ovarian follicles to IGF1 in mares

Seasonal effects on the response of ovarian follicles to IGF1 in mares

Comportamento De Éguas Após a Inserção De Dispositivo Intravaginal Impregnado Com Progesterona

A clinical view of mare reproductive physiology

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