Effects of repeated transvaginal ultrasound-guided aspirations performed in anestrous and cyclic mares on P4 and E2 plasma levels and luteal function.
Abstract: The aim of the present study was to verify how repeated ovum pick-up (OPU), performed in anestrous and cyclic mares, affect ovarian activity, measured by progesterone (P4) and 17ß-estradiol (E2) plasma levels. Ovum pick-up of all visible follicles was performed every 9 to 12 days, and four sessions were carried out during anestrous (A) and breeding season (BS). The number of aspirated follicles per mare at each session was not significantly different between the two periods (BS: 6.1 ± 2.4; A: 7.5 ± 4.4; P > 0.05), but the mean follicular diameter was significantly higher during BS (16.0 ± 7.1 vs. 10.2 ± 5.1 mm; P < 0.05); during A the number of aspirated follicles less than 15 mm in diameter resulted significantly higher than that registered in BS (5.1 ± 2.7 vs. 3.0 ± 1.8; P < 0.05). The total mean value of P4 was higher in BS than in A (6.3 ± 4.4 vs. 0.3 ± 1.8 ng/mL; P 0.05). Estradiol plasma values resulted positively correlated, in A and BS, with diameter of follicles detected on the ovaries (R = 0.345 and R = 0.331, respectively), whereas a negative correlation was observed between P4 and follicular diameter in BS (R = -0.162). Both E2 and P4 presented a high individual variability during BS; in particular, in three of seven mares, P4 trend was compatible with a normal estrous cycle, and the interval between two consecutive peaks was 21 days. In two of seven mares, with CL at first OPU, P4 concentrations remained more than 3 ng/mL throughout the entire treatment period. Finally, in two of seven animals, P4 levels initially showed a similar pattern to that of a normal estrous cycle, then, after the second aspiration, they remained consistently higher than 3 ng/mL. When the procedure was carried out in cyclic animals, the influence of this technique on ovarian activity seemed to be related to individual variability although, according to progesterone values, structures observed on the ovaries after aspirations presented luteal function. Furthermore, the resumption of normal ovarian activity, after repeated OPU sessions, occurred in a period not much longer than the duration of a normal estrous cycle (25.4 ± 5.2 days). Data recorded during nonbreeding period showed that repeated OPU in anestrous mares do not affect ovarian activity and do not anticipate the resumption of ovarian cyclicity. However, based on the number of aspirated follicles in anestrous and cyclic mares, both types of subjects could be considered as oocyte donors.
Copyright © 2014 Elsevier Inc. All rights reserved.
Publication Date: 2014-04-04 PubMed ID: 24780115DOI: 10.1016/j.theriogenology.2014.03.025Google Scholar: Lookup
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Summary
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The research study aimed to investigate the impact of frequent ovum pick-up (OPU) on ovarian activity in anestrous (non-breeding) and cyclic (breeding) mares by analyzing progesterone (P4) and estradiol (E2) plasma levels. The results demonstrated that repeated OPU didn’t vastly affect ovarian activity, even in anestrous mares, implying that both categories of mares could potentially act as oocyte donors.
Research Design and Methodology
- The researchers carried out OPU on all visible follicles every 9 to 12 days.
- Four sessions of OPU were performed during anestrous (A) and breeding season (BS).
- They measured the quantity and diameter of the aspirated follicles in each session to determine if there were differences between the anestrous and breeding periods.
- Additionally, the researchers measured levels of the hormones progesterone (P4) and estradiol (E2) in plasma samples.
Results and Observations
- There was no significant difference in the number of aspirated follicles between the breeding and anestrous periods.
- The average size of the follicles, however, was significantly larger during the breeding period.
- During the anestrous period, a significantly higher number of follicles less than 15mm in size were aspirated.
- The total mean value of progesterone was higher in the breeding season than in the anestrous period, while estradiol levels did not differ significantly between the two periods.
- A positive correlation was observed between estradiol levels and follicle size in both periods, while a negative correlation was observed between progesterone levels and follicle size in the breeding season.
Implications of the Findings
- Individual variability was evidenced during the breeding season when it comes to estradiol and progesterone levels.
- Some mares’ progesterone pattern was congruous with a normal estrous cycle, and the interval between two consecutive peaks was about 21 days.
- In some cases, progesterone concentrations remained continuously high (more than 3 ng/mL) throughout the entire treatment period— especially in mares with Corpus luteum at the commencement of OPU.
- When the OPU procedure is performed in cyclic animals, the influence on ovarian activity appears to be heavily contingent on individual variability.
- Further, the progression of normal ovarian activity after repeated OPU sessions happens in a period not much longer than a typical estrous cycle.
- Data recorded during the non-breeding season revealed that repeated OPU in anestrous mares does not significantly affect ovarian activity or expedite the resumption of ovarian cyclicity.
- From the number of aspirated follicles in anestrous and cyclic mares, it’s suggested that both types of mares could potentially be sources for oocyte donation.
Cite This Article
APA
Iacono E, Merlo B, Rizzato G, Mislei B, Govoni N, Tamanini C, Mari G.
(2014).
Effects of repeated transvaginal ultrasound-guided aspirations performed in anestrous and cyclic mares on P4 and E2 plasma levels and luteal function.
Theriogenology, 82(2), 225-231.
https://doi.org/10.1016/j.theriogenology.2014.03.025 Publication
Researcher Affiliations
- Department of Veterinary Medical Sciences, University of Bologna, Ozzano Emilia, Bologna, Italy. Electronic address: eleonora.iacono2@unibo.it.
- Department of Veterinary Medical Sciences, University of Bologna, Ozzano Emilia, Bologna, Italy.
- National Institute of Artificial Insemination, University of Bologna, Cadriano, Bologna, Italy.
- National Institute of Artificial Insemination, University of Bologna, Cadriano, Bologna, Italy.
- Department of Veterinary Medical Sciences, University of Bologna, Ozzano Emilia, Bologna, Italy.
- Department of Veterinary Medical Sciences, University of Bologna, Ozzano Emilia, Bologna, Italy.
- Department of Veterinary Medical Sciences, University of Bologna, Ozzano Emilia, Bologna, Italy; National Institute of Artificial Insemination, University of Bologna, Cadriano, Bologna, Italy.
MeSH Terms
- Animals
- Breeding
- Estradiol / blood
- Estrous Cycle / physiology
- Female
- Horses / physiology
- Oocyte Retrieval / adverse effects
- Oocyte Retrieval / veterinary
- Ovarian Follicle / diagnostic imaging
- Seasons
- Ultrasonography / veterinary
Citations
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