Animal Reproduction (AR)
https://animal-reproduction.org/article/doi/10.1590/1984-3143-AR2024-0085
Animal Reproduction (AR)
ORIGINAL ARTICLE

Effects of exogenous GnRH administration at insemination on pregnancy rates of estrus-synchronized seven ewe populations during the breeding season

Shuyuan Sun; Nana Yang; Jing Zhang; Xinglong Wu; Yiyong Liu; Xiangyun Li

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Abstract

The objective of this study was to investigate the effects of GnRH at insemination on pregnancy and lambing in seven ewe populations during the breeding season. Estrus was synchronized in 1560 adult ewes using an intravaginal sponge impregnated with flurogestone acetate. The sponge was left in the vagina for 12 days followed by an injection of 330 IU of eCG at sponge removal. Each ewe was inseminated twice at 48 h and 60 h after sponge removal. The treatment group was intramuscularly injected at the first insemination with a dose of 16 μg GnRH and the control group with saline solution in each ewe population. The results showed that GnRH administration significantly decreased the pregnancy rate in three ewe populations, but had no effects in four ewe populations. Additionally, the litter size tended to increase in the treatment group compared to the control group in all seven ewe populations, but the difference was not significant. In conclusion, GnRH administration at insemination was not recommended for ewes undergoing a timed artificial insemination during the breeding season. The breed/population may be a critical determinant of the potential for exploiting GnRH application in sheep breeding programs.

Keywords

GnRH, timed artificial insemination, pregnancy rate, litter size, sheep

References

Ayaseh M, Mirzaei A, Boostani A, Mehrvarz M. The effect of prostaglandin and gonadotrophins (GnRH and hCG) injection combined with the ram effect on progesterone concentrations and reproductive performance of Karakul ewes during the non-breeding season. Vet Med Sci. 2021;7(1):148-55. http://doi.org/10.1002/vms3.353. PMid:32951343.

Azawi OI, Al-Mola MK. A study on the effect of GnRH administration on the ovarian response and laparoscopic intrauterine insemination of Awassi ewes treated with eCG to induce superovulation. Trop Anim Health Prod. 2011;43(7):1351-5. http://doi.org/10.1007/s11250-011-9856-7. PMid:21509456.

Balaro MF, Fonseca JF, Barbosa TG, Souza-Fabjan JM, Figueira LM, Teixeira TA, Carvalheira LR, Brandão FZ. Potential role for GnRH in the synchronization of follicular emergence before the superovulatory Day 0 protocol. Domest Anim Endocrinol. 2016;54:10-4. http://doi.org/10.1016/j.domaniend.2015.07.002. PMid:26343000.

Biehl MV, Ferraz MVC Jr, Ferreira EM, Polizel DM, Miszura AA, Barroso JPR, Oliveira GB, Bertoloni AV, Pires AV. Effect of reproductive methods and GnRH administration on long-term protocol in Santa Ines ewes. Trop Anim Health Prod. 2017;49(6):1303-8. http://doi.org/10.1007/s11250-017-1329-1. PMid:28608308.

Cam MA, Kuran M, Yildiz S, Selcuk E. Fetal growth and reproductive performance in ewes administered GnRH agonist on day 12 post-mating. Anim Reprod Sci. 2002;72(1-2):73-82. http://doi.org/10.1016/S0378-4320(02)00071-4. PMid:12106967.

Cavalcanti A, Brandao F, Nogueira L, Fonseca J. Effects of GnRH administration on ovulation and fertility in ewes subjected to estrous synchronization. Rev Bras Zootec. 2012;41(6):1412-8. http://doi.org/10.1590/S1516-35982012000600014.

Fernandez J, Bruno-Galarraga MM, Soto AT, de la Sota RL, Cueto MI, Lacau-Mengido IM, Gibbons AE. Effect of GnRH or hCG administration on Day 4 post insemination on reproductive performance in Merino sheep of North Patagonia. Theriogenology. 2019;126:63-7. http://doi.org/10.1016/j.theriogenology.2018.12.008. PMid:30530159.

Gibbons A, Bruno-Galarraga M, Fernandez J, Gonzalez-Bulnes A, Cueto M. Vitrified embryo transfer in Merino sheep under extensive conditions. Anim Reprod. 2019;16(2):297-301. http://doi.org/10.21451/1984-3143-AR2018-0108. PMid:33224290.

Gonźalez-Bulnes A, Baird DT, Campbell BK, Cocero MJ, García-García RM, Inskeep EK, López-Sebastián A, McNeilly AS, Santiago-Moreno J, Souza CJ, Veiga-López A. Multiple factors affecting the efficiency of multiple ovulation and embryo transfer in sheep and goats. Reprod Fertil Dev. 2004;16(4):421-35. http://doi.org/10.1071/RD04033. PMid:15315741.

Hameed N, Khan MI, Zubair M, Andrabi SMH. Approaches of estrous synchronization in sheep: developments during the last two decades: a review. Trop Anim Health Prod. 2021;53(5):485. http://doi.org/10.1007/s11250-021-02932-8. PMid:34581865.

Ishida N, Okada M, Sebata K, Minato M, Fukui Y. Effects of GnRH and hCG treatments for enhancing corpus luteum function to increase lambing rate of ewes artificially inseminated during the non-breeding season. J Reprod Dev. 1999;45(1):73-9. http://doi.org/10.1262/jrd.45.73.

Kutlu M, Dinç DA. The effect of double-dose GnRH injections on reproductive performance parameters following short-term progestagen administration in lactated Awassi ewes during the non-breeding season. Trop Anim Health Prod. 2021;53(2):277. http://doi.org/10.1007/s11250-021-02735-x. PMid:33884517.

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):32-9. http://doi.org/10.1016/j.anireprosci.2010.11.007. PMid:21176867.

Menchaca A, Rubianes E. New treatments associated with timed artificial insemination in small ruminants. Reprod Fertil Dev. 2004;16(4):403-13. http://doi.org/10.1071/RD04037. PMid:15315739.

Menchaca A, Vilariño M, Pinczak A, Kmaid S, Saldaña JM. Progesterone treatment, FSH plus eCG, GnRH administration, and Day 0 Protocol for MOET programs in sheep. Theriogenology. 2009;72(4):477-83. http://doi.org/10.1016/j.theriogenology.2009.04.002. PMid:19515409.

Olivera-Muzante J, Fierro S, López V, Gil J. Comparison of prostaglandin- and progesterone-based protocols for timed artificial insemination in sheep. Theriogenology. 2011;75(7):1232-8. http://doi.org/10.1016/j.theriogenology.2010.11.036. PMid:21247622.

Olivera-Muzante J, Gil J, Viñoles C, Fierro S. 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):175-9. http://doi.org/10.1016/j.anireprosci.2013.02.013. PMid:23537480.

Reyna J, Thomson PC, Evans G, Maxwell WM. Synchrony of ovulation and follicular dynamics in merino ewes treated with GnRH in the breeding and non-breeding seasons. Reprod Domest Anim. 2007;42(4):410-7. http://doi.org/10.1111/j.1439-0531.2006.00800.x. PMid:17635779.

Rubianes E, Menchaca A. The pattern and manipulation of ovarian follicular growth in goats. Anim Reprod Sci. 2003;78(3-4):271-87. http://doi.org/10.1016/S0378-4320(03)00095-2. PMid:12818649.

Sirjani MA, Kohram H, Shahir MH. Effects of eCG injection combined with FSH and GnRH treatment on the lambing rate in synchronized Afshari ewes. Small Rumin Res. 2012;106(1):59-63. http://doi.org/10.1016/j.smallrumres.2012.04.022.

Titi HH, Kridli RT, Alnimer MA. Estrus synchronization in sheep and goats using combinations of GnRH, progestagen and prostaglandin F2α. Reprod Domest Anim. 2010;45(4):594-9. PMid:19055549.

Türk G, Gür S, Sönmez M, Bozkurt T, Aksu EH, Aksoy H. Effect of exogenous GnRH at the time of artificial insemination on reproductive performance of Awassi ewes synchronized with progestagen–PMSG–PGF2α combination. Reprod Domest Anim. 2008;43(3):308-13. http://doi.org/10.1111/j.1439-0531.2007.00896.x. PMid:18067532.

Walker SK, Smith DH, Ancell P, Seamark RF. Time of ovulation in the South Australian Merino ewe following synchronization of estrus. 2. Efficacy of GnRH treatment and its relevance to insemination programs utilizing frozen-thawed semen. Theriogenology. 1989;31(3):555-64. http://doi.org/10.1016/0093-691X(89)90240-9. PMid:16726574.

Walker SK, Smith DH, Seamark RF. Timing of multiple ovulations in the ewe after treatment with FSH or PMSG with and without GnRH. J Reprod Fertil. 1986;77(1):135-42. http://doi.org/10.1530/jrf.0.0770135. PMid:3088268.
 


Submitted date:
06/21/2024

Accepted date:
01/11/2025

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