Effect of ovulatory follicle size and expression of estrus on progesterone secretion in beef cows

Controlling the timing of ovulation in cows that fail to conceive after insemination would provide a further opportunity for scheduled rebreeding in a group of cows to save time and optimise results. The ear implant Crestar containing the synthetic progestagen norgestomet provides a means of achieving this control (Sinclair et al., 1992; Lowman et al., 1994). Removing the implant on day 25 after oestrus results in less false positive pregnancy diagnoses than removal on day 21 with the implant in place for nine/ten days. However, treatment of beef heifers with a norgestomet implant towards the end of luteal phase to control oestrus and ovulation is associated with development of a persistent ovulatory follicle and reduced pregnancy rate (Mihm et al., 1994). The objective of this study was to determine the effects of treating beef cows with one or two norgestomet implants on the development of the dominant ovulatory follicle of the second follicular wave.

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Relationship of pre-ovulatory follicle size, estradiol concentrations and season to pregnancy outcome in dairy cows

Animal Reproduction Science ◽

10.1016/j.anireprosci.2006.04.056 ◽

2007 ◽

Vol 99 (1-2) ◽

pp. 34-43 ◽

Cited By ~ 61

Author(s):

A.S. Lopes ◽

S.T. Butler ◽

R.O. Gilbert ◽

W.R. Butler

Keyword(s):

Dairy Cows ◽

Pregnancy Outcome ◽

Ovulatory Follicle ◽

Follicle Size ◽

Relationship Of

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ENDOCRINE CHANGES ASSOCIATED WITH LUTEAL REGRESSION IN THE EWE; THE SECRETION OF OVARIAN OESTRADIOL, PROGESTERONE AND ANDROSTENEDIONE AND UTERINE PROSTAGLANDIN F2α THROUGHOUT THE OESTROUS CYCLE

Journal of Endocrinology ◽

10.1677/joe.0.0690275 ◽

1976 ◽

Vol 69 (2) ◽

pp. 275-286 ◽

Cited By ~ 59

Author(s):

D. T. BAIRD ◽

R. B. LAND ◽

R. J. SCARAMUZZI ◽

A. G. WHEELER

Keyword(s):

Luteal Phase ◽

Venous Blood ◽

Prostaglandin F2α ◽

Significant Rise ◽

Functional Regression ◽

Luteal Regression ◽

Progesterone Secretion ◽

Ovulatory Follicle ◽

Prostaglandin F ◽

Relationship Of

SUMMARY The concentrations of oestradiol, androstenedione, progesterone and prostaglandin F2α (PGF2α) were measured in utero-ovarian venous blood collected throughout six oestrous cycles in two ewes with utero-ovarian autotransplants. The secretion of oestradiol was closely correlated with that of androstenedione (r = 0·67, P < 0·001) indicating a common origin from the Graafian follicle. The concentration of these two steroids fluctuated at random throughout the luteal phase with the maximum secretion occurring about 2 days before the onset of oestrus. Functional regression of the corpus luteum, as indicated by a fall in the secretion of progesterone, began on day 12 or day 13, i.e. about 4 days before the onset of oestrus. In five of the six cycles the first significant rise in the secretion of PGF2α occurred on days 12–14 at the time of decline of progesterone secretion, although the release of PGF2α was maximal on the day before the onset of oestrus. There was very little release of PGF2α from the uterus before day 12. The temporal relationship of these events suggests that the uterus will only release PGF2α after it has been primed for 7–10 days with progesterone. The initiation of luteal regression is independent of secretion of oestradiol by the pre-ovulatory follicle which may, however, stimulate the further release of PGF2α responsible for irreversible structural luteolysis on the day of pro-oestrus.

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Effect of ovulatory follicle size on bovine pregnancy associated glycoproteins in beef cattle

10.32469/10355/8069 ◽

2010 ◽

Author(s):

Cia L. Johnson

Keyword(s):

Beef Cattle ◽

Ovulatory Follicle ◽

Bovine Pregnancy ◽

Follicle Size

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Determinants of Embryo Development and Quality in Beef Cattle: Effect of Pre-Ovulatory Follicle Size, CL Volume, and Serum Concentrations of Progesterone.

Biology of Reproduction ◽

10.1093/biolreprod/81.s1.505 ◽

2009 ◽

Vol 81 (Suppl_1) ◽

pp. 505-505 ◽

Cited By ~ 1

Author(s):

Jacqueline A. Atkins ◽

Michael F. Smith ◽

Michael D. MacNeil ◽

Thomas W. Geary

Keyword(s):

Beef Cattle ◽

Embryo Development ◽

Serum Concentrations ◽

Ovulatory Follicle ◽

Follicle Size

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Factors influencing reproductive efficiency and pregnancy in Pura Raza Española mares

Veterinární Medicína ◽

10.17221/205/2015-vetmed ◽

2017 ◽

Vol 62 (No. 4) ◽

pp. 186-191

Author(s):

A. Akourki ◽

A. Echegaray ◽

MV Falceto ◽

O. Mitjana

Keyword(s):

Pregnancy Loss ◽

Post Partum ◽

Reproductive Efficiency ◽

Ovarian Activity ◽

Gestation Length ◽

Ovulatory Follicle ◽

Follicle Size ◽

Spss Software ◽

Twin Pregnancies ◽

Length Of Gestation

The aim of this study was to analyse ovarian activity and pregnancy in 140 Pura Raza Espanola mares over a period of two consecutive years. The data were analysed using SPSS software to evaluate the effects of age, category of mares and season on pre-ovulatory follicle size, ovulation rate, interval from foaling to pregnancy, gestation length, incidence of twin pregnancies and pregnancy losses. The results showed that follicular diameter was significantly (P < 0.05) smaller in fillies (3-year-old) and maiden mares than in older and multiparous mares. Within the group of animals treated with gonadotropin hormone hCG, 87.23% ovulated 48 h following administration. Length of gestation varied from 305 to 356 days and all gestation pregnancies of less than 305 days resulted in a non-viable foal. In addition, foaling season affected (P < 0.05) the post-partum conception interval and the length of gestation, which were shorter and longer in the winter foaling, respectively. Regarding the other parameters, mares of this stud exhibited relatively very low rates of double ovulations, twin pregnancies and pregnancy losses. We conclude that age and category of mares and foaling season influence fertility and foaling rates by affecting pre-ovulatory follicle size, pregnancy loss and gestation length.

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