Effects of neutralization of pregnant mares’ serum gonadotrophin (PMSG) shortly before or at the preovulatory LH surge in PMSG-superovulated heifers on follicular function and development.
Abstract: Normally cyclic heifers (n = 34) received 2500 iu pregnant mares' serum gonadotrophin (PMSG) i.m. at day 10 of oestrus, and 15 mg prostaglandin (PG) i.m. at day 12. Thereafter, a monoclonal antibody against PMSG was administered i.v. before (n = 24), at (n = 6) or shortly after (n = 4) the preovulatory LH surge. Peripheral blood concentrations of LH and oestradiol were compared; follicular development was monitored by daily ultrasound scanning; and the numbers of preovulatory-sized follicles and ovulations were counted 96 h after injection of PG following death. Anti-PMSG treatment before the LH surge inhibited the LH surge in 16 heifers (67%). In these heifers, the initial increase in oestradiol concentration upon PMSG stimulation to 167.5 +/- 35.0 pmol l-1 was terminated immediately after anti-PMSG treatment and decreased rapidly to basal values, while the number of preovulatory-sized follicles remained constant until 68 h after PG injection; on average 0.4 +/- 0.1 ovulations were counted. In the remaining eight heifers, five animals showed an immediate, but temporary, 20-60% drop in oestradiol concentration after anti-PMSG treatment. In all eight heifers 25% of the preovulatory-sized follicles ovulated. Treatment with anti-PMSG at or shortly after the LH surge did not affect the pattern of oestradiol concentration, but a significantly higher ovulation rate was observed in the animals treated shortly after the LH surge: 20.3 +/- 2.6 versus 6.3 +/- 2.3 in animals treated at the LH surge, which corresponded to 76% and 24% of the preovulatory-sized follicles monitored shortly before the period of multiple ovulation.(ABSTRACT TRUNCATED AT 250 WORDS)
Publication Date: 1994-03-01 PubMed ID: 8021854DOI: 10.1530/jrf.0.1000387Google Scholar: Lookup
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Summary
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This research explores the effects of neutralizing Pregnant Mare Serum Gonadotrophin (PMSG) at different stages during a heifer’s reproductive cycle. The study finds that neutralising PMSG before the LH surge inhibits the surge in most heifers and leads to a drop in oestradiol concentration. However, neutralizing PMSG at or after the LH surge does not affect oestradiol patterns, yet it does influence ovulation rates.
Research Methodology
- The subjects of this research were 34 regularly cycling heifers. These animals were administered Pregnant Mares’ Serum Gonadotrophin (PMSG) and prostaglandin on day 10 and 12 of oestrus, respectively.
- Then, a monoclonal antibody against PMSG was injected intravenously before, at, or shortly after the preovulatory LH (luteinizing hormone) surge in different groups of heifers.
- Changes in peripheral blood concentrations of LH and oestradiol were closely monitored and compared. The researchers also observed follicular development using daily ultrasound scans.
Key Findings
- Neutralizing PMSG before the LH surge inhibited the surge in a significant majority (67%) of the heifers.
- In heifers where the LH surge was inhibited, there was an immediate termination of the initial increase in oestradiol concentration following PMSG stimulation. This concentration then quickly decreased to basal values.
- However, the number of preovulatory-sized follicles remained constant in these heifers for up to 68 hours after the prostaglandin injection.
- In five out of eight cases where the LH surge was not inhibited, there was a temporary drop in oestradiol concentrations following anti-PMSG treatment. In these eight heifers, ovulation occurred for 25% of the preovulatory-sized follicles.
- When the anti-PMSG was administered at or shortly after the LH surge, it did not affect oestradiol concentrations but did influence ovulation rates.
- Significantly higher ovulation rates were observed in animals treated with the anti-PMSG shortly after the LH surge than in animals treated at the time of the LH surge.
Conclusions
- The timing of PMSG neutralization affects both oestradiol concentration and ovulation rates in heifers, with different effects observed when the neutralizer is administered before, at, or after the LH surge.
- The research provides valuable insights that may inform strategies for influencing reproductive outcomes in cattle.
Cite This Article
APA
Vos PL, van der Schans A, de Wit AA, Bevers MM, Willemse AH, Dieleman SJ.
(1994).
Effects of neutralization of pregnant mares’ serum gonadotrophin (PMSG) shortly before or at the preovulatory LH surge in PMSG-superovulated heifers on follicular function and development.
J Reprod Fertil, 100(2), 387-393.
https://doi.org/10.1530/jrf.0.1000387 Publication
Researcher Affiliations
- Department of Herd Health and Reproduction, Faculty of Veterinary Medicine, University of Utrecht, The Netherlands.
MeSH Terms
- Animals
- Antibodies, Monoclonal / administration & dosage
- Cattle
- Estradiol / blood
- Female
- Gonadotropins, Equine / immunology
- Gonadotropins, Equine / pharmacology
- Luteinizing Hormone / blood
- Luteinizing Hormone / metabolism
- Ovarian Follicle / physiology
- Radioimmunoassay
- Superovulation / physiology
Citations
This article has been cited 2 times.- Baruselli PS, Soares JG, Bayeux BM, Silva JCB, Mingoti RD, Carvalho NAT. Assisted reproductive technologies (ART) in water buffaloes. Anim Reprod 2018 Jul-Sep;15(Suppl 1):971-983.
- Galli C, Lazzari G. 40 years of AETE: the contribution of scientists and practitioners to the progress of reproductive biotechnologies in Europe. Anim Reprod 2024;21(3):e20240061.
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