Influence of stage of oestrous cycle on time of oestrus

Jackson, Peter; Johnson, Carl T.; Furr, B. J. A.; Beattie, John F

doi:10.1016/0093-691x(79)90081-5

Cited by 41 publications

(8 citation statements)

References 26 publications

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“…Ultrasound measurements have since shown that cows have either two or three discrete waves of follicular development during each cycle (Webb and others 1992). Days 7 to 8 and 15 to 16 apparently coincide with the peaks of follicular development in cows which are undergoing three waves, the most common pattern (Webb and others 1992), an observation which fits well with the earlier findings of Jackson and others (1979). Thus, if a group of randomly cycling cows is treated with PGF 2α some of the variation in timing of oestrus and ovulation will be due to differences in their follicular status, that is, whether a large follicle is present which can be ovulated or whether a smaller follicle has to grow from a much earlier stage of development.…”

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confidence: 88%

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Ovarian and hormonal responses of cows to treatment with an analogue of gonadotrophin releasing hormone and prostaglandin F_2α

et al. 1999

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Blood samples were taken from 11 cows and their ovaries were scanned by ultrasound at least daily. Around day 5 of an induced cycle, they were injected with 10 micrograms buserelin, an analogue of gonadotrophin releasing hormone, and on day 12 they received 0.5 mg cloprostenol, an analogue of prostaglandin F2 alpha (PGF2 alpha). Two days later six of the cows (the treated group) received a second injection of 10 micrograms buserelin, but the remaining five received no further treatment (control group). The dominant, that is, the largest follicle in each cow disappeared after the first buserelin injection and was replaced by a new one which grew synchronously in all the cows until after the treatment with PGF2 alpha. Ovulation occurred significantly earlier after PGF2 alpha in the treated group than in the control group (72 to 96 hours v 96 to 120 hours; P < 0.05). Plasma progesterone concentrations then increased more rapidly in the treated group than in the control group and were significantly higher on days 3 and 4 after ovulation (P < 0.05).

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supporting

confidence: 88%

“…It has also been known for some time that part of the variation in the timing of oestrus is dependent on the day of the cycle on which the PGF 2α is injected (Jackson and others 1979). Heifers injected on days 7 to 8 or 15 to 16 showed a preovulatory surge of luteinising hormone (LH) earlier than those injected on days 12 to 14.…”

mentioning

confidence: 99%

Ovarian and hormonal responses of cows to treatment with an analogue of gonadotrophin releasing hormone and prostaglandin F_2α

et al. 1999

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“…Application of repeated ultrasound measurements to ovarian morphology has since shown that cows have either two or three discrete waves of follicle development during each cycle (see Webb et aL, 1992). In fact days 7-8 and 15-16 coincide with peaks of follicle development occurring in cows undergoing three waves (the most common pattern) and therefore this fits well with the earlier findings of Jackson et al (1979). Thus if a group of randomly cycling cows are treated with PG, some of the variation in timing of oestrus and ovulation will be due to differences in their follicular status, i.e.…”

Section: Introductionsupporting

confidence: 86%

“…Furthermore it has been known for some time that a proportion of cows show oestrus up to several days after fixed time A1 and Ball (1982) has shown that A1 at oestrus observed after PG gives better fertility results than double fixed time AI. It has been known for almost 20 years that part of the variation in timing of oestrus is dependent on the day of the cycle on which PG is injected (Jackson et al, 1979). Cows injected on days 7-8 or 15-16 showed oestrus earlier than those injected on days 12-14.…”

Section: Introductionmentioning

confidence: 99%

Studies on the Timing of Ovulation After Synchronisation Treatments in Cattle

Peters

Benboulaid

1998

Reprod Domestic Animals

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ContentsA series of studies was conducted to examine the effect of various GnRH -PG -GnRH regimes on the timing of ovulation using ultrasound in cows. In Study 1 cows received GnRH on day 5 of the oestrous cycle followed 7 days later by PG. Six cows received a second GnRH 48 hours after PG. These cows ovulated between 72 and 96 hours after PG compared to 96 and 120 hours for those not receiving a second GNRH. In Study 2, 32 cows received a first GNRH injection at a random stage of the cycle. When PG was injected 7 days later 29/32 were in the luteal phase. Eleven cows received a second GnRH at 56-60 hours after PG and 10 cows at 72 hours, the other 11 receiving no hrther treatment. Ovulation was most tightly synchronised in the group receiving GnRH at 56-60 hours, 10/11 ovulating between 72 and 96 hours after PG. In Study 3 six cows received PG on day 12 of the cycle followed by GnRH 60 hours later. Five of the six cows ovulated between 84 and 96 hours after PG. In Study 4, 6 cows received GnRH on day 17 of the cycle followed by PG 7 days later and GnRH 60 hours after PG. The first GnRH successhlly prolonged the luteal phase in 516 cows. Although the remaining cow ovulated 48 hours after PG, the others ovulated between 84 and 96 hours after PG. It is concluded from these studies that GnRH given 48-60 hours after PG is most critical in determining the time of ovulation, GnRH 72 hours after PG is clearly too late. The first GnRH treatment does not appear to influence the timing of ovulation but could be important in determining oocyte maturation through reprogramming follicular development several days before luteolysis is induced. The first GnRH also has the effect of delaying luteolysis if given late in the luteal phase.

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“…• comparar a resposta à administração de diferentes doses de Gonadotrofina PETERS, 1999;JACKSON et al, 1979;KNOPF;GINTHER, 1990;MACMILLAN;HENDERSON, 1984;VIANA;FERREIRA;CAMARGO, 1999). O mesmo foi constatado por Porto-Filho (2000) em búfalas.…”

Section: In Nt Tr Ro Od Du Uç çã ãO Ounclassified

Sincronização da ovulação para a inseminação artificial em tempo fixo (IATF) durante a estação reprodutiva desfavorável em fêmeas bubalinas

Filho¹,

Mendes²

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Influence of stage of oestrous cycle on time of oestrus

Cited by 41 publications

References 26 publications

Ovarian and hormonal responses of cows to treatment with an analogue of gonadotrophin releasing hormone and prostaglandin F_2α

Ovarian and hormonal responses of cows to treatment with an analogue of gonadotrophin releasing hormone and prostaglandin F_2α

Studies on the Timing of Ovulation After Synchronisation Treatments in Cattle

Sincronização da ovulação para a inseminação artificial em tempo fixo (IATF) durante a estação reprodutiva desfavorável em fêmeas bubalinas

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Influence of stage of oestrous cycle on time of oestrus

Cited by 41 publications

References 26 publications

Ovarian and hormonal responses of cows to treatment with an analogue of gonadotrophin releasing hormone and prostaglandin F2α

Ovarian and hormonal responses of cows to treatment with an analogue of gonadotrophin releasing hormone and prostaglandin F2α

Studies on the Timing of Ovulation After Synchronisation Treatments in Cattle

Sincronização da ovulação para a inseminação artificial em tempo fixo (IATF) durante a estação reprodutiva desfavorável em fêmeas bubalinas

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Ovarian and hormonal responses of cows to treatment with an analogue of gonadotrophin releasing hormone and prostaglandin F_2α

Ovarian and hormonal responses of cows to treatment with an analogue of gonadotrophin releasing hormone and prostaglandin F_2α