Ovulation and the descent of the ovum in the Fallopian tube of the mare after treatment with gonadotrophic hormones

Day, F. T.

doi:10.1017/s0021859600052187

Cited by 36 publications

(20 citation statements)

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“…In a study carried out on Breton mares 10 , the average time for ovulation occurrence was shorter and ovulation synchrony increased with the injection of 1500 IU and 2500 IU of hCG when compared to mares treated with 500 IU. The results of our study ( Figure 1) are similar to those 1,8,11,12 , where mares ovulated within 48…”

Section: Referencessupporting

confidence: 87%

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Indução da ovulação com gonadotrofina coriônica humana em éguas Crioulas

Beal¹,

Rubin

Côrte

et al. 2011

Braz. J. Vet. Res. Anim. Sci.

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The effect of age, follicular diameter and month of the breeding season (September to January) on the hCG induction of ovulation was evaluated using 123 Criollo mares. Age varied between two and 24 years and the animals were examined daily by rectal palpation and ultrasonography with a 5 MHz linear transducer. When ovarian follicles reached a diameter of 30 to 35 mm, ovulation was induced with an i.v. injection of 1000 IU (n = 39); 1500 IU (n = 41) or 2000 IU (n = 43) of hCG. The mares were bred the next day and examined daily until ovulation was detected. The percentage of mares ovulating before 24 h of hCG injection was 10.3%, 7.3% and 4.7%; until 48 h after injection 92.3%, 85.3% and 86.0% of the mares treated with 1000, 1500 and 2000 IU of hCG, respectively, ovulated. The month of the breeding season, age of the mares and follicular diameter had no influence on ovulatory response. The three hCG doses used in Criollo mares (P > 0.05) result in the induction of ovulation within 48 h after injection when a pre-ovulatory follicle with a 30 to 35 mm diameter was identified. A single dose of 1000 IU of hCG is efficient to induce ovulation in Criollo mares. Keywords:Criollo. Follicular diameter. Equine. hCG. ResumoO efeito da idade, diâmetro folicular e mês da estação de monta (setembro a janeiro) na indução da ovulação com hCG foi avaliado em 123 éguas Crioulas. A idade das éguas variou entre dois e 24 anos e os animais foram examinados diariamente por palpação retal e ultrassonografia com transdutor linear de 5 MHz. Quando os folículos ovarianos atingiram diâmetro de 30 a 35 milímetros aplicou-se uma injeção intravenosa com 1000 UI (n = 39); 1500 UI (n = 41) ou 2000 UI (n = 43) de hCG. As éguas foram cobertas no dia seguinte e examinadas diariamente até a detecção da ovulação. O percentual de éguas que ovularam antes de 24 h da injeção de hCG foi de 10,3%, 7,3% e 4,7%, até 48h após a injeção foi de 92,3%, 85,3% e 86,0%, nos grupos com 1000, 1500 e 2000 UI de hCG, respectivamente. O mês da estação de monta, a idade das éguas ou o diâmetro folicular não influenciaram a resposta ovulatória. As três doses de hCG utilizadas em éguas Crioulas (P > 0,05) resultaram na indução da ovulação dentro de 48h após a aplicação, quando foi identificado um folículo pré-ovulatório de 30 a 35 mm de diâmetro. Uma única dose de 1000 UI de hCG é eficiente para induzir a ovulação em éguas Crioulas. Palavras-chave:Crioulo. Diâmetro folicular. Equinos. hCG.

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Section: Referencessupporting

confidence: 87%

“…The ideal dose for ovulation induction in mares has still not been determined and routinely several authors use 2500 IU of hCG 1,7,9,10 .…”

Section: Referencesmentioning

confidence: 99%

Indução da ovulação com gonadotrofina coriônica humana em éguas Crioulas

Beal¹,

Rubin

Côrte

et al. 2011

Braz. J. Vet. Res. Anim. Sci.

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“…However, eCG is a pituitary gonadotropin which stimulates the secondary follicular growth and ovulation, to cause the formation of accessory luteal tissue (Allen, 1975;Evans and Irvine, 1975). In mares, there is no positive effect of eCG on follicular development and ovulation (Day, 1940(Day, , 1939, although eCG has been widely used to induce superovulation in several mammalian species due to its containing both LH and FSH (Butt et al, 1970Rowson, 1971. The reason eCG is does not function in mares has been unveiled by Stewart and Allen (Stewart and Allen, 1979).…”

Section: Equine Chorinoic Gonadotropin (Ecg or Pmsg)mentioning

confidence: 99%

The Estrous Cycle and Induction of Ovulation in Mares

Yoon¹

2012

Journal of Animal Science and Technology

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For horse breeders or managers, it is critical to understand the estrous cycle of mares. Breeding of mares cannot be successfully achieved throughout the whole year as mares breed seasonally. Mares are only able to breed when day length is more than 16 h, and this period is known as the breeding season. Their estrous cycle is approximately 21 days with 5-7 days of estrus and 14 to 15 days of a diestrus period. The estrous cycle of the mare is mainly controlled by gonadotropins, which control follicular development and ovulation. Mares exhibit unique ovulatory events which are not observed in other species. A LH surge occurs for several days, with levels of LH reaching their peak after ovulation. The LH level at the time of LH peak is lower than most other species. The unique anatomical structure of the ovaries of mares is known to limit the number of eggs ovulated. Several attempts have been made to develop chemical/hormonal agents which might be used to manipulate the timed ovulation of mares. Agents that have been tested include hCG, native GnRH, Deslorelin (Ovuplant, GnRH-agonist), Buserelin (GnRH analogue), equine pituitary extracts and equine chorionic gonadotropin (eCG or PMSG). However, the function, purity or stability of these agents is not reliable. Recombinant equine LH, an alternative agent for the timed ovulation, has been developed and tested for its biological activities, through the use of both in vitro and in vivo experiments. The reLH was suggested to be a reliable agent in inducing ovulation within 48 h after being administered through injection, when the size of dominant follicle is 35 mm in diameter.

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“…Classically, induction of ovulation in a short predictable time (24-48 h) is easily obtained by hCG both in mares (Day, 1939;Barbacini et al, 2000) and jennies (Carluccio et al, 2007) but it is well known that the effectiveness of hCG is reduced by successive injections (Duchamp et al, 1987). GnRH agonists deslorelin acetate (deslorelin, 1.5 or 2.25 mg, implant, Meinert et al, 1993) and buserelin acetate (buserelin, 6 mg, Levy and Duchamp, 2007) resulted in the mare in ovulation rates between 24 and 48 h similar to hCG.…”

Section: Introductionmentioning

confidence: 99%