Study of Reproductive Performance of Crossbred Ewes Treated with GnRH and PMSG during Breeding Season

Document Type: Research Articles


Department of Animal Science, Faculty of Agriculture, University of Tabriz, Tabriz, Iran


Reproductive performance was evaluated in non-lactating crossbred ewes to which were administered the exogenous GnRH and PMSG. The ewes were randomly allocated in three treatment groups (n=40).After accurate detection of estrus and 2 hours prior to mating, 2.5 mL of distilled water and 2.5 mL of GnRH were injected intramuscular to each ewe of the first (control) and second group, respectively. In the third group, the ewes were pretreated with CIDR for 14 days and received 400 IU PMSGat the time of withdrawal of the CIDR. After injection of PMSG, fixed-time artificial insemination was performed with 0.5 mL of fresh diluted semen. No significant differences were observed in term of the pregnancy, lambing, and fecundity rates between ewes treated with GnRH and control group (87.5, 97.5, and 1.114% vs. 75, 82.5, and 1.1%, respectively). Twining rate was higher in the ewes treated with GnRH than synchrony or control groups (18.18, 4, and 6.5%respectively, P<0.05). In the artificially inseminated group, pregnancy, lambing and fecundity rates were 77.5, 62.5, and 0.81%, respectively. In conclusion, the results showed that treatment of ewes with GnRH at time of estrus and prior to mating, improved the conception and twining birth rates. Also injection of PMSG after CIDR removal caused an increase in efficiency of fertility rate and shorter breeding period.


Akif Cam M. and Kuran M. (2004). Effects of a single injection of hCG or GnRH agonist on day 12 post mating on fetal growth and reproductive performance of sheep. Anim. Reprod. Sci. 80, 81-90.
Alifakiotis T. (1986). Increasing ovulation rate and lambing percentage by active immunization against androstenedione in dairy sheep breeds. Theriogenology. 25, 681-688.
Bartlewski P.M., Beard A.P., Chapman C.L., Nelson M.L., Palmer B., Aravindakshan J., Cook S.J. and Rawlings N.C. (2001). Ovarian responses in GnRH-treated anoestrous ewes: follicular and endocrine correlates with luteal outcome. Reprod. Fertil. Dev. 13, 133-142.
Boscos C.M., Samartzi F.C., Dellis S., Rogge A., Stefanakis A. and Krambovitis E. (2002). Use of progestagen-gonadotrophin treatments in estrus synchronization of sheep. Theriogenology. 58, 1261-1272.
Bowen J.M., Dahl G.E., Evans N.P., Thrun L.A., Wang Y., Brown M.B. and Karsch F.J. (1998). Importance of the gonadotropin-releasing hormone (GnRH) surge for induction of the preovulatory luteinizing hormone surge of the ewe: dose-response relationship and excess of GnRH. Endocrinology. 139, 588-595.
Cooper R.A. (1982). The Agricultural Notebook. 17th edition, Edited by R.J. Halley, Seal-Hayne Collage, U.K.
Dogan L. and Nur Z. (2006). Different estrous induction methods during the non-breeding season in Kivircik ewes. Vet. Medical. 51, 133-138.
Driancourt M.A., Fry R.C., Clarke I.J. and Cahill L.P. (1987). Follicular growth and regression during the 8 days after hypophysectomy in sheep. J. Reprod. Fertil. 79, 635-641.
Drion P.V. and Roover R.D. (2001). Increase of plasma eCG binding rate after administration of repeated high dose of eCG to cows. Reprod. Nutr. Dev. 41, 207-215.
Eppleston J., Evans G. and Roberts E.M. (1991). Effect of time of PMSG and GnRH on the time of ovulation, LH secretion and reproductive performance after intrauterine insemination with frozen ram semen. J. Anim. Reprod. Sci. 26, 227-237.
Gatica G.R. and Correa J.E. (1993). Manufacturing chimeric ovine-caprine embryos. Agro-Sur. 21, 101-108.
Geary T.W., Downing E.R., Bruemmer J.E. and Whittier J.C. (2000). Ovarian and estrous response of suckled beef cows to select synch estrous synchronization protocol. Prof. Anim. Sci. 16, 1-5.
Greyling J.P.C. and Van Der Nest M. (2000). Synchronization of oestrus in goats: dose effect of progestagen. Small Rumin. Res. 36, 201-207.
Greyling J.P.C. and Van Niekerk C.H. (1991). Different synchronization techniques in Boer goat do outside the normal breeding season. Small Rumin. Res. 5, 233-243.
Hashemi M., Safdarian M. and Kafi M. (2006). Estrous response to synchronization of estrus using different progesterone treatments outside the natural breeding season in ewes. Small Rumin. Res. 65, 279-283.
Henderson K.M. (1979). Gonadotrophic regulation of ovarian activity. British Med. Bull. 35, 161-166.
Hunter M.G., Southee J.A., McLeod B.J. and Haresign W. (1986). Progesterone pretreatment has a direct effect on GnRH induced preovulatory follicles to determine their ability to develop into normal corpora lutea in anoestrous ewes. J. Reprod. Fertil. 76, 349-363.
Husein M.Q. and Ababneh M.M. (2008). A new strategy for superior reproductive performance of ewes bred out-of-season utilizing progestagen supplement prior to withdrawal of intravaginal pessaries. Theriogenology. 69, 376-383.
Husein M.Q., Ababneh M.M. and Haddad S.G. (2005). The effects of progesterone priming on reproductive performance of GnRH–PGF2 a-treated anestrous goats. Reprod. Nutr. Dev. 45, 689-698.
Husein M.Q. and Kridli, R.T. (2003). Effect of progesterone prior to GnRH–PGF2a treatment on induction of oestrus and pregnancy in anoestrous Awassi ewes. Reprod. Domest. Anim. 38, 228-232.
Jafari K. (2008). Agriculture Organization of East Azerbaijan Province in Iran.
Jafariahangari Y., Monem M. and Arab M. (1997). Investigation and determination of fertility efficiency of Moghani ewes after artificial insemination using diluted ram semen in Tris buffer or cow skimmed milk. J. Res. construction. 34, 132-135.
Khaldari M., Tajik P., Afzalzadeh A. and Farzin N. (2003). Efficacy of CIDR and eCG on estrus synchronization and twining rate Zandi ewes during the breeding season. J. Vet. Res. 2, 141-145.
Khan T.H., Hastie P.M., Beck N.F.G. and Khalid M. (2003). hCG treatment on day of mating improves embryo viability and fertility in ewe lambs. Anim. Reprod. Sci. 76, 81-89.
Kim U.H., Suh G.H., Nam H.W., Kang H.G. and Kim I.H. (2005). Follicular wave emergence, luteal function and synchrony of ovulation following GnRH or estradiol benzoate in a CIDR treated, lactating Holstein cows. Theriogenology. 63, 260-268.
Lopez-Alonso C., Encinas T., Veiga-Lopez A., Garcia-Garcia R.M., Cocero M.J., Ros J.M., McNeilly A.S. and Gonzalez-Bulnes A. (2005). Follicular growth, endocrine response and embryo yields in sheep superovulated with FSH after pretreatment with a single short-acting dose of GnRH antagonist. Theriogenology. 64, 1833-1843.
Macmillan K.L., Segwagwe B.E. and Pino C.S. (2003). Associated between the manipulation of patterns of follicular development and fertility in cattle. Anim. Reprod. Sci. 78, 327-344.
Mandiki S.N., Noel B., Bister J.L., Peeters R., Beerlandt G., Decuypere E., Visscher A., Suess R., Kaulfuss K.H. and Paquay R. (2000). Pre-ovulatory follicular characteristics and ovulation rates in different breed crosses, carriers or non-carriers of the Booroola or Cambridge fecundity gene. Anim. Reprod. Sci. 63, 77-88.
McLeod B.J. and Haresign W. (1984). Response of seasonally anoestrous ewes to small-dose multiple injections of GnRH with and without progesterone pretreatment. J. Reprod. Fertil. 65, 223-230.
Menchaca A., Vilarino M., Pinczak A., Kmaid S. and Saldana J.M. (2009). Progesterone treatment, FSH plus eCG, GnRH administration, and Day 0 Protocol for MOET programs in sheep. Theriogenology. 72, 477-483.
Moeini M.M., Moghaddam A.A., Bahirale A. and Hajarian, H. (2007). Effects of breed and progestin source on estrus synchronization and rates of fertility and fecundity in Iranian Sanjabi and Lori Ewes. Pakistan. J. Biol. Sci. 10, 3801-3807.
Mohd Azam A., Noor Hashim H. and Ismail N. (2009). Effect of PMSG on the behavioral estrus and hormonal profile in synchronized ewes. Turk. J. Vet. Anim. Sci. 35(1), 903-915.
Naohisa I., Midori O., Kazuhide S., Mayuko M. and Yutaka F. (1999). 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. 45, 73-90.
Pearce D.T. and Robinson T.J. (1985). Plasma progesterone concentration ovarian and endocrinological responses and sperm transport in ewes with synchronized estrous.J. Reprod. Fertil. 75, 49-62.
Pierson J.T., Baldassarre H., Keefer C.L. and Downey B.R. (2003). Influenced of GnRH administration on timing of the LH surge and ovulation in dwarf goats. Theriogenology. 60, 397-406.
Ptaszynska M. (2001). Ovine Reproduction. In: Compendium of Animal Reproduction. Ptaszynska, M. Ed 6th Revised edn. Intervet Int. Bv. The Netherlands.
Reyna J., Thomson P.C., Evans G. and Maxwell W.M. (2007). Synchrony of ovulation and follicular dynamics in merino ewes treated with GnRH in the breeding and non-breeding seasons. Reprod. Dom. Anim. 42, 410-417.
Safranski T.J., Lamberson W.R. and Keisler D.H. (1992). Use of melengestrol acetate and gonadotropins to induce fertile estrus in seasonally anestrous ewes. J. Anim. Sci. 70, 2935-2941.
SAS. (2003). SAS Users Guide. SAS Institute Inc. Cary, NC.
Simonetti L., Forcada F. and Rivera O.E. (2008). Simplified superovulatory treatments in Corriedale ewes. Anim. Reprod. Sci. 104, 227-237.
Sirjani M.A., Shahir M.H., Khoram H. and Zare Shahneh A. (2011). Effect of gonadotropin-releasing hormone (GnRH) treatment on multiple births in Afshari ewes. African. J. Biotechnol. 57, 12358-12362.
Titi H.H., Kridli R.T. and Alnimer M.A. (2010). Estrus synchronization in sheep and goats using combinations of GnRH, progestagen and prostaglandin F. Reprod. Domest. Anim. 45, 594-599.
Turk G., Gur S., Sonmez M., Bozkurt T., Aksu E.H. and Aksoy H. (2008). 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. 43, 308-313.
Twagiramungu H., Guilbault L.A., Proulx J., Villeneuve P. and Dufour J.J. (1992). Influence of an agonist of GnRH (buserelin) on estrus synchronization and fertility in beef cows.J. Anim. Sci. 70, 1904-1910.
Wheaton J.E., Carlson K.M., Windels H.F. and Johnston L.J. (1993). CIDR: A new progesterone-releasing intravaginal device for induction of estrus and cycle control in sheep and goats. Anim. Reprod. Sci. 33, 127-141.
Zare Shahneh A., Mohammadi Z., Fazeli H., Moradi shahre Babak M. and Dirandeh E. (2008). The effect of GnRH injection on plasma progesterone concentrations, conception rate and ovulation rate in Iranian Holstein cows. J. Anim. Vet. Advance. 7(9), 1137-1141.
Zeleke M., Greyling J.P.C., Schwalbach L.M.J., Muller and T. Eramus J.A. (2005). Effect of progestagen and PMSG on oestrus synchronization and fertility in Dorper ewes during the transition period. Small Rumin. Res. 56, 47-53.