Veterinary Research Forum
Vet Res Forum

Effects of human chorionic gonadotropin on reproductive outcomes in estrus-synchronized ewes subjected to two different insemination methods

Document Type : Short Communication

Authors

Jing Zhang 1, 2
Yiyong Liu 3
Nana Yang 2
Shuyuan Sun 2
Xiangyun Li 2
Xinglong Wu 1, 2

1 Institute of Biotechnology, Xinjiang Academy of Animal Science, Key Laboratory of Genetic Breeding and Reproduction of Herbivorous Livestock of Ministry of Agriculture, Xinjiang Key Laboratory of Animal Biotechnology, Urumqi, China

2 College of Animal Science and Technology, Hebei Technology Innovation Center of Cattle and Sheep Embryo, Hebei Agricultural University, Baoding, China

3 Institute of Xinjiang Yili Animal Science, Yining, China

https://doi.org/10.30466/vrf.2025.2041893.4475
Abstract
This study compared the effects of a dose of human chorionic gonadotropin (hCG) administration at the time of insemination on the reproductive outcome of estrus-synchronized Mongolian ewes subjected to two artificial insemination methods during the breeding season. All females were treated with a polyurethane intravaginal sponge impregnated with 45.00 mg of flurogestone acetate for 12 days, followed by an intramuscular injection of 330 IU of equine chorionic gonadotropin at sponge removal. In Experiment 1, 150 ewes were inseminated using a laparoscopic intrauterine artificial insemination method 48 hr after sponge removal. The ewes were randomly assigned to the hCG group which received 500 IU of hCG at the time of insemination, and the control group which received 1.00 mL of sterile saline solution. In Experiment 2, 85 ewes were inseminated twice at 48 and 60 hr after sponge removal using a cervical artificial insemination method. The ewes were randomly assigned to the hCG group, which received 500IU of hCG at the time of the first insemination and the control group which received 1.00 mL of sterile saline solution. The pregnancy rate in the control group was not significantly different compared to the hCG group in Experiment 1 and the pregnancy rate in the control group was significantly higher compared to the hCG group in Experiment 2. In conclusion, the administration of hCG at the time of insemination could not be recommended in ewes when implementing a fixed time artificial insemination protocol during the breeding season.

Keywords

Cervical insemination
HCG
Laparoscopic insemination
Pregnancy rate
Sheep

Subjects

1.     Türk G, Gür S, Sönmez M, et al. Effect of exogenous GnRH at the time of artificial insemination on reproductive performance of Awassi ewes synchronized with progestagen-PMSG-PGF2alpha combination. Reprod Domest Anim 2008; 43(3): 308-313.
2.     Zhang J, Lu X, Liu Y, et al. Prolonging the time of semen deposition increases the pregnancy rates of ewes subjected to fixed time cervical insemination during the breeding season. Reprod Domest Anim 2022; 57(10): 1280-1284.
3.     Sylla L, Pistolesi A, Corsi I, et al. Laparotomic intrauterine insemination with frozen-thawed semen in Sopravissana breed ewes in Central Italy. Ital J Anim Sci 2021; 20(1): 928-934. 
4.     Santos-Jimenez Z, Meza-Herrera CA, Calderon-Leyva G, et al. Efficiency of hCG for inducing resumption of ovarian cyclicity and synchronized ovulations during the seasonal anestrous in sheep. Animals (Basel) 2021; 11(11): 3159. doi: 10.3390/ani11113159.
5.     Hameed N, Khan MI, Zubair M, et al. Approaches of estrous synchronization in sheep: developments during the last two decades: a review. Trop Anim Health Prod 2021; 53(5): 485.doi: 10.1007/s11250-021-02932-8.
6.     Martemucci G, D'Alessandro AG. Synchronization of oestrus and ovulation by short time combined FGA, PGF(2α), GnRH, eCG treatments for natural service or AI fixed-time. Anim Reprod Sci 2011; 123(1-2):32-39.
7.     Olivera-Muzante J, Gil J, Viñoles C, et al. Reproductive outcome with GnRH inclusion at 24 or 36h following a prostaglandin F2α-based protocol for timed AI in ewes. Anim Reprod Sci 2013; 138(3-4):175-179.
8.     Garcia-Ispierto I, De Rensis F, Casas X, et al. Inducing ovulation with hCG in a five-day progesterone-based fixed-time AI protocol improves the fertility of anestrous dairy cows under heat stress conditions. Theriogenology 2019; 124: 65-68.
9.     Bruno-Galarraga M, Cano-Moreno V, Lago-Cruz B, et al. The use of hCG for inducing ovulation in sheep estrus synchronization impairs ovulatory follicle growth and fertility. Animals (Basel) 2021; 11(4): 984. doi: 10.3390/ani11040984.
10. Rodrigues JND, Guimarães JD, Oliveira MEF, et al. Human chorionic gonadotropin affects original (ovulatory) and induced (accessory) corpora lutea, progesterone concentrations, and pregnancy rates in anestrous dairy goats. Reprod Biol 2022; 22(1): 100591. doi: 10.1016/j.repbio.2021.100591.
11. Khan TH, Hastie PM, Beck NF, et al. hCG treatment on day of mating improves embryo viability and fertility in ewe lambs. Anim Reprod Sci 2003; 76(1-2): 81-89.
12. Rodrigues JND, Guimarães JD, Rangel PSC, et al. Luteal function in cyclic goats treated with human chorionic gonadotropin administered by intramuscular or intravaginal routes at the time of artificial insemination. Reprod Domest Anim 2023; 58(3): 396-404.
13. King C, Osborn D, Grupen CG. Multiple ovulation and embryo transfer in sheep: effects of embryo developmental stage and quality on viability in vivo under farm conditions. Aust Vet J 2022; 100(9):451-458.
14. Dias LMK, Sales JNS, Viau P,et al. Although it induces synchronized ovulation, hCG reduces the fertility of Santa Ines ewes submitted to TAI. Arq Bras Med Vet Zootec 2018; 70(1): 122-130.
15. Dias JH, Miranda VO, Oliveira FC, et al. Treatment with eCG and hCG to induce onset of estrous cycles in ewes during the non-breeding season: effects on follicular development and fertility. Anim Reprod Sci 2020; 212: 106232. doi: 10.1016/j.anireprosci.2019.106232.
16. Santos IW, Binsfeld LC, Weiss RR, et al. Fertility rates of ewes treated with medroxyprogesterone and injected with equine chorionic gonadotropin plus human chorionic gonadotropin in anoestrous season. Vet Med Int 2010; 2010: 978520. doi: 10.4061/2010/978520.
17. Habeeb HMH, Hazzard TM, Stormshak F, et al. Effect of different dosages of PG-600 on ovulation and pregnancy rates in ewes during the breeding season. Transl Anim Sci 2018; 3(1): 429-432.
18. Zamiri MJ, HosseiniM. Effects of human chorionic gonadotropin (hCG) and phenobarbital on the reproductive performance of fat-tailed Ghezel ewes. Small Rumin Res 1998; 30(3): 157-161.
19. Shabankareh HK, Seyedhashemi SB, Torki M, et al. Effects of repeated administration of hCG on follicular and luteal characteristics and serum progesterone concentrations in eCG-superovulated Sanjabi ewes. Trop Anim Health Prod 2012; 44(8): 1865-1871.
20. Gómez-Brunet A, Santiago-Moreno J, Monotor V, et al. Reproductive performance andprogesterone secretion in estrus-induced Manchega ewes treated with hCG at thetime ofAI. Small Rumin Res 2007; 71(1-3): 117-122.
21. Oliveira MEF, Arrais AM, Vergani GB, et al. Hormonal-induced cervical relaxation during diestrus in ewes: cervical transposing feasibility and use of hCG for rescuing disrupted luteal function. J Appl Anim Welf Sci 2024; 27(4): 635-651.
Veterinary Research Forum
Volume 16, Issue 12
December 2025
Pages 707-711

  • Receive Date 29 September 2024
  • Revise Date 27 November 2024
  • Accept Date 01 February 2025

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