Effects of Equine Chorionic Gonadotropin on Ovulatory and Luteal Characteristics of Mares Submitted to an P4-Based Protocol of Ovulation Induction With hCG.
Abstract: The aim of this study was to evaluate the effect of equine chorionic gonadotropin (eCG) at the end of progesterone (P4) treatment on follicular and luteal characteristics during transition period (TP) and reproductive breeding season (RP). A total of 13 crossbred mares were distributed in two experimental groups in the spring and summer (n = 26). The animals received intravaginal P4 (1.9 g) releasing device from D0 to D10. On removal of P4 device, the mares received 400 IU of eCG (eCG group) or saline solution (control group). Human chorionic gonadotropin (hCG; 1.750 IU) was administered (DhCG) as soon as ovulatory follicle (OF) ≥35 mm was detected. Ovarian ultrasonography was performed from D0 until 15 days after ovulation. Blood samples were collected on D0, D5, D10, DhCG, 9 days after ovulation (CL9D), and 13 days after ovulation (CL13D). P4 and estradiol concentrations were assessed by chemiluminescence. Data were compared by Tukey test at P < .05. Ovulation rate was similar (P = .096) between seasons (RP = 100%; TP = 70%) but occurred earlier (P = .015) in RP (34.8 ± 10.1 hours) compared with TP (42.0 ± 10.4 hours). Interactions between season and treatment were observed for OF diameter (mm) (RP/control = 36.2 ± 1.8ab; RP/eCG = 32.9 ± 2.8 b; TP/control = 32.2 ± 1.2 b; TP/eCG = 37.2 ± 1.9a; P = .004) and for corpus luteum (CL) diameter (mm) on CL13D (RP/control = 25.4 ± 3.5a; RP/eCG = 22.5 ± 1.8ab; TP/control = 21.6 ± 4.9 b; TP/eCG = 27.4 ± 4.3a; P = .023), although no differences were observed for serum P4 on CL13D (RP/control = 6.0 ± 3.1 ng/mL; RP/eCG = 5.8 ± 0.9 ng/mL; TP/control = 3.6 ± 2.7 ng/mL; TP/eCG = 5.1 ± 2.3 ng/mL; P = .429) or for day of structural CL regression (RP/control = 12.8 ± 1.9; RP/eCG = 12.1 ± 1.1; TP/control = 11.0 ± 1.7; TP/eCG = 13.2 ± 2.0; P = .102). The application of eCG at the moment of P4 implant removal seemed to increase the capacity of luteal maintenance during spring TP. However, eCG treatment was worthless during the breeding season.
Copyright © 2020 Elsevier Inc. All rights reserved.
Publication Date: 2020-08-25 PubMed ID: 33077076DOI: 10.1016/j.jevs.2020.103233Google Scholar: Lookup
The Equine Research Bank provides access to a large database of publicly available scientific literature. Inclusion in the Research Bank does not imply endorsement of study methods or findings by Mad Barn.
- Journal Article
- Research Support
- Non-U.S. Gov't
Summary
This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.
This study examined the impact of equine chorionic gonadotropin (eCG) on mare reproductive cycles during different seasons. The researchers found eCG increased the capacity for luteal maintenance in the spring transition period, though it didn’t appear to be beneficial during the breeding season.
Objective of the Study
- The main objective of this study was to understand how eCG affects the reproductive cycles of mares during the transition period (TP) and reproductive breeding season (RP). The researchers were particularly interested in how eCG affects follicular and luteal characteristics after treatment with progesterone (P4), and how seasons may influence these effects.
Methods and Procedures
- The study involved 13 crossbred mares used as experimental subjects, divided into two groups and studied over spring and summer seasons. The horses were treated with an intravaginal P4 release device from day 0 (D0) to day 10 (D10). On removal of this device, some mares were treated with 400 IU of eCG, while others received a saline solution as the control group.
- To induce ovulation, the mares were given 1,750 IU of human chorionic gonadotropin (hCG) once an ovulatory follicle sized at least 35 mm was detected. Ovarian ultrasonography was conducted from D0 until 15 days after ovulation to monitor and record data.
Findings
- The results showed that the rate of ovulation was similar across both the RP and TP, but occurred earlier during the RP. Interactions were observed between seasons and treatment for ovulatory follicle (OF) diameter and corpus luteum (CL) diameter, especially on the 13th day after ovulation. However, no differences were noted for serum P4 on the 13th day after ovulation or for the day of structural CL regression.
- The application of eCG at the time of P4 device removal seemed to enhance the ability for luteal maintenance during the spring transition period. However, it was found to be ineffective during the breeding season.
Conclusions
- The study concludes that while eCG can help to increase the capacity for luteal maintenance in the spring transition period, it does not appear to be beneficial during the breeding season. This knowledge can lead to improved reproductive and fertility management practices in horses, especially during different seasons.
Cite This Article
APA
Teixeira ACB, Valle GR, Riveros JAN, Diniz JHW, Wenceslau RR, Monteiro GA, Leme FOP, Oliveira LZ.
(2020).
Effects of Equine Chorionic Gonadotropin on Ovulatory and Luteal Characteristics of Mares Submitted to an P4-Based Protocol of Ovulation Induction With hCG.
J Equine Vet Sci, 94, 103233.
https://doi.org/10.1016/j.jevs.2020.103233 Publication
Researcher Affiliations
- Escola de Veterinária, Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG, Brazil.
- Pontifícia Universidade Católica de Minas Gerais (PUC Minas), Betim, MG, Brazil.
- Escola de Veterinária, Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG, Brazil.
- Escola de Veterinária, Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG, Brazil.
- Escola de Veterinária, Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG, Brazil.
- Escola de Veterinária, Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG, Brazil.
- Escola de Veterinária, Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG, Brazil.
- Escola de Veterinária, Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG, Brazil. Electronic address: leticiazo@vet.ufmg.br.
MeSH Terms
- Animals
- Chorionic Gonadotropin / pharmacology
- Corpus Luteum
- Female
- Gonadotropins, Equine / pharmacology
- Horses
- Insemination, Artificial / veterinary
- Ovulation Induction / veterinary
Citations
This article has been cited 3 times.- Jitjumnong J, Yama P, Sangkate M, Suriard A, Butmata W, Daoloy N, Taweechaipaisankul A, Buddhasiri S, Lin CJ, Zhang Y, Moonmanee T. Rewiring the luteal microenvironment: hemodynamic and molecular insights into eCG-supported CL development in indigenous White Lamphun cattle. Reprod Fertil 2025 Oct 1;6(4).
- Alkhadrawy JMH, Aboelmaaty AM, Abou-Ahmed MM, Ghallab AM. Effect of hCG and prostaglandin on ovarian, luteal development, and hormonal changes in embryo donor mares during the hot summer months in subtropics. Open Vet J 2024 Aug;14(8):2057-2072.
- Alkhadrawy JMH, Aboelmaaty AM, Abou-Ahmed MM, Ghallab AM. Effect of breeding season and age on follicular dynamics and hemodynamics in embryo donor mares subjected to luteolysis after embryo flushing. Open Vet J 2024 Mar;14(3):852-865.
Use Nutrition Calculator
Check if your horse's diet meets their nutrition requirements with our easy-to-use tool Check your horse's diet with our easy-to-use tool
Talk to a Nutritionist
Discuss your horse's feeding plan with our experts over a free phone consultation Discuss your horse's diet over a phone consultation
Submit Diet Evaluation
Get a customized feeding plan for your horse formulated by our equine nutritionists Get a custom feeding plan formulated by our nutritionists
