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Fate of the Dominant Follicle, Embryonal Survival, and Pregnancy Rates in Dairy Cattle Treated with Prostaglandin F2a and Progestins in the Absence or Presence of a Functional Corpus Luteum1

Fate of the Dominant Follicle, Embryonal Survival, and Pregnancy Rates in Dairy Cattle Treated with Prostaglandin F2a and Progestins in the Absence or

Fate of the Dominant Follicle, Embryonal Survival, and Pregnancy Rates in Dairy Cattle Treated with Prostaglandin F2a and Progestins in the Absence or Presence of a Functional Corpus Luteum1   (Citations: 51)
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Our objective was to examine the role of progestin type on serum concentrations of progesterone ( P 4) and estradiol-17b (E2) , ovarian follicular dynamics, and fertility in cattle in the presence or absence of a corpus luteum (CL) in an estrus synchronization scheme using progestin and PGF2a. In Exp. 1, 325 cows and heifers were given one injection of PGF2a (d 0 ) and then assigned randomly within parity to five treatments: to receive a second PGF2a injection 14 d later (control); to receive norgestomet (NORG) for 7 d beginning on d 8, with a second PGF2a injection given either 1 d (NORG + no CL) or 6 d (NORG + CL) after insertion; or to receive aP 4 -releasing intravaginal device (PRID) in lieu of norgestomet at comparable times. Presence or absence of a CL was based on concentrations of serum P4 on d 14. Pregnancy rates after insemination were greater ( P < .01) with luteal treatments than with nonluteal treatments. Embryonal survival between two stages of pregnancy was 87.6%. In Exp. 2, ovarian structures in 50 cows were examined daily using ultrasonography and the same five treatments. Diameter of the ovulatory follicle was greater ( P < .05) with the nonluteal treatments (NORG and PRID + no CL) than with the control and luteal treatments (PRID and NORG + CL). Replacement of the dominant follicle during progestin treatment was altered by treatment (luteal status) and stage of the estrous cycle. Fertility was not enhanced by exogenous proges- tins when a CL was present. In the absence of a CL, progestin ( P 4 less than NORG at the doses used) reduced fertility by increasing E2 and the diameter of the ovulatory follicle and decreasing turnover of dominant follicles.
Published in 2010.
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    • ...In the absence of a function corpus luteum (1, 22), a maturing follicle persists in the ovaries and fails to turn over in the presence of limited concentrations of progestins, which are produced via feeding of melengestrol acetate (9), exposure to a removable progestin implant (17), or intravaginal progesteronecontaining device (6)...
    • ...Doses of progestins typically administered in estrus-synchronization programs are not sufficient to prevent increased LH pulse frequency (9, 17) or the development of persistent follicles (9, 17, 22)...

    J. S. Stevensonet al. Reproductive Outcomes for Dairy Heifers Treated with Combinations of P...

    • ...Consequently,based onthepresent results,we canonly suggest that a similar proportion of cows were cyclic after the Ovsynch with or without P4. As a result, improved fertility using exogenous P4 during the Ovsynch protocol might be explained because of greater concentrationsofP4beforeTAIdetermineingbettersynchronizationofovulationthanwouldnosupplementationwith P4 (Wehrman et al., 1993; Smith and Stevenson, 1995; Stevenson et al., 2006)...

    P. Melendezet al. Comparison of Two Estrus-Synchronization Protocols and Timed Artificia...

    • ...Reported pregnancy losses in lactating dairy cows are greater than that in dairy heifers (20 vs. 5%; Smith and Stevenson, 1995)...
    • ...The 10.2% pregnancy loss in the present study is greater than that reported by Smith and Stevenson (1995) but less than the 20.5% (Smith and Stevenson, 1995) and the 13.5% (Fricke et al., 1998) reported during a comparable stage of pregnancy in lactating dairy cows...
    • ...The 10.2% pregnancy loss in the present study is greater than that reported by Smith and Stevenson (1995) but less than the 20.5% (Smith and Stevenson, 1995) and the 13.5% (Fricke et al., 1998) reported during a comparable stage of pregnancy in lactating dairy cows...

    H. Riveraet al. Fertility of Holstein Dairy Heifers after Synchronization of Ovulation...

    • ...Similarly, pregnancy loss in lactating dairy cows is greater than that in dairy heifers (20% vs. 5%; Smith and Stevenson, 1995)...

    Paul M. Fricke. Monitoring Reproduction From the Starting Gate

    • ...Similarly, pregnancy loss in lactating dairy cows is greater than that in dairy heifers (20 vs. 5%; Smith and Stevenson, 1995)...

    P. M. Fricke. Scanning the Future—Ultrasonography as a Reproductive Management Tool ...

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