Currently, there is an intense effort to find an alternative hormone to eCG to induce ovulation after estrus synchronization treatments in sheep. One of the proposed alternatives is based on the use of hCG, but the results are controversial since fertility rates are commonly affected. The present study aims to evaluate, therefore, the adequacy of hCG in protocols for the synchronization of estrus and ovulation. Ovarian follicle dynamics, occurrence of estrus behavior and subsequent ovulation, quality of corpora lutea, and pregnancy rate after controlled natural mating were assessed in two consecutive trials. The findings indicate that the low fertility rates reported for the protocols based on the administration of hCG for inducing ovulation during estrus synchronization in sheep may be related to a high occurrence of abnormal follicular growth patterns, disturbances, and retardments of ovulation and concomitant formation of follicular cysts in the treated females. These results preclude their practical application to induce ovulation concomitantly to estrous synchronization treatments.
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http://dx.doi.org/10.3390/ani11040984 | DOI Listing |
Theriogenology
January 2025
Department of Animal Sciences, University of Florida, Gainesville, FL, USA. Electronic address:
Implementing accelerometer technologies in beef operations is an alternative to increase precision in estrous detection. We hypothesized that (1) the accelerometer algorithm has similar accuracy in detecting behavioral estrus as does visual observation of pressure-sensitive sensors (estrus patches) in grazing beef cows; (2) variables measured by the accelerometer, such as estrus intensity, are associated with hormonal, ovarian, and uterine variables monitored before, during, and after estrus; and (3) the accelerometer variables are associated with the probability of pregnancy in grazing beef cows submitted to embryo transfer (ET). Fifty cows were fitted with accelerometer and patches to detect estrus after a synchronization protocol in eight subsequent rounds.
View Article and Find Full Text PDFBMC Vet Res
December 2024
Department of Animal Science, Faculty of Agriculture, University of Peradeniya, Peradeniya, 20400, Sri Lanka.
Background: Reproductive efficiency is paramount in the dairy industry, where early pregnancy detection of dairy cows will allow to detect the non-pregnant animals early, thus enabling to re-synchronize them and getting them pregnant leading to decrease in calving interval, which, in turn, is critical for maximizing productivity and economic gain. The objective of this study was to evaluate the colour Doppler ultrasonography (CDUS) and peripheral blood leukocytes (PBLs)-based pregnancy-associated biomarker mRNAs expression for the earliest detection of pregnancy status in the dairy cows at post insemination. Intensively managed animals were ovulation synchronized and subjected to timed artificial insemination (TAI).
View Article and Find Full Text PDFJ Dairy Sci
January 2025
Department of Animal Science, University of São Paulo, Piracicaba, SP, Brazil, 13418-900. Electronic address:
The study evaluated strategies for induction of ovulation at the end of timed AI (TAI) protocols initiated after a novel presynchronization strategy. A total of 909 lactating dairy cows from 6 dairy herds initiated a presynchronization protocol on d -15 with an intravaginal progesterone (P4) implant and 7 d later (d -8) were treated with 1.0 mg of estradiol cypionate (EC) and 0.
View Article and Find Full Text PDFTheriogenology
March 2025
Agrotecnio Center, Department of Animal Sciences, University of Lleida, Lleida, 25198, Spain. Electronic address:
The main objectives of the present study were to determine the effects of presynchronizing with a 1.0 g intravaginal progesterone device (IVPD) and prostaglandin F2α and to assess the effects of re-utilization of IVPD in a 2x2 factorial design, on the ovulatory response to first GnRH, ovarian status at different protocol stages, estrus expression and fertility in beef heifers submitted to a 5d-CO-Synch + Progesterone (P4) protocol. Beef heifers (n = 564) were assigned to 1 of 2 treatments at D-15: Pres5 (n = 283), where heifers received a (IVPD) for 5 days and administration of prostaglandin F2α (25 mg of dinoprost) at D-10; and Control (n = 281), where heifers received no treatment.
View Article and Find Full Text PDFTheriogenology
March 2025
Universidade Estadual Paulista "Julio de Mesquita Filho", Botucatu, SP, 18618-000, Brazil. Electronic address:
The aims of this study were to: 1) evaluate the impact of intravaginal progesterone (P4) inserts containing different amounts of P4 on pregnancy rates of predominantly Bos taurus beef cows exposed to fixed-time artificial insemination (FTAI) using estradiol and P4-based synchronization protocols, and 2) evaluate the impact of delayed luteolysis on the fertility of cows receiving P4 insert with less P4. Cows (n = 1744) were randomly assigned to 1 of 3 treatments: 1) 2.0 mg of estradiol benzoate together with an intravaginal P4-releasing insert containing 1.
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