Effects of increased exposure time to eCG on reproductive performance in estrus-synchronized Farahani ewes

Document Type : Technical Note


Department of Animal Science, Faculty of Agriculture and Natural Science, Arak University, Arak 38156-8-8349, Iran.


It seems that; long exposure to equine chorionic gonadotropin (eCG) in ewe synchronization programs would stimulate the growth of ovarian follicles resulting in better reproductive performance. Therefore, the aim of present study was to expose Farahani ewes to longer duration of eCG by using an eCG-alhydrogel mixture as a slow-release eCG. Fifty Farahani ewes (3-4 years, 44 ± 1.3 kg BW, BCS 3.04±0.3 on scale 1 to 5) were treated with controlled internal drug release (CIDR) for 14 days. The experimental groups consisted of: control group receiving no eCG, and four groups of ewes receiving either 400 IU eCG or eCG-alhydrogel preparation (i.m.) at 24 h (-24S, and -24SR groups, respectively), or 48 h (-48S and -48SR groups, respectively) prior to CIDR removal. Blood samples were taken from two days before until one day after CIDR removal. Reproductive performance was recorded at lambing. There was no difference (P>0.05) between groups in terms of the pregnancy rate, lambing rate, fertility, multiple birth and fecundity. However orthogonal contrasts showed that the fecundity and multiple birth were higher (p <0.05) in eCG-alhydrogel ewes. In all groups, estradiol concentration showed an increasing trend with time (p <0.05). Estradiol concentration was significantly higher in the -48SR compared with the -48S group; no difference was observed between 24S and -24SR ewes (P>0.05). The findings indicated that in an estrous synchronization protocol, administration of slow- release eCG preparations might improve the fecundity and multiple births in sheep.

Keywords: alhydrogel, estrous synchronization, Farahani ewe, reproductive performance


Main Subjects

  • Ali, A., 2007. Effect of time of eCG administration on follicular response and reproductive performance of FGA-treated Ossimi ewes. Small Ruminant Research 72, 33-37.
  • Andriyanto, A., Min, R., Arief, B. Wasmen, M., 2017. Optimum dose and time of pregnant mare serum gonadotropin injections in Kacang goats to increase endogenous secretion of estrogen and progesterone without superovulation response. Small Ruminant Research 149, 147-153.
  • Bó, G.A. Mapletoft, R.J., 2014. Historical perspectives and recent research on superovulation in cattle. Theriogenology 81, 38-48.
  • Bó, G.A. Mapletoft, R.J., 2020. Superstimulation of ovarian follicles in cattle: Gonadotropin treatment protocols and FSH profiles. Theriogenology 150, 353-359.
  • Boshoff, D. Burger, F., 1973. Limitation of multiple ovulations in Karakul ewes after the use of PMSG. South African Journal of Animal Science 3, 79-81.
  • Demoustier, M., Beckers, J.F., Van Der Zwalmen, P., Closset, J., Gillard, J. Ectors, F., 1988. Determination of porcine plasma follitropin levels during superovulation treatment in cows. Theriogenology 30, 379-386.
  • Dias, L.M.K., De Barros, M.B.P., Viau, P., De Sousa Sales, J.N., Valentim, R., Dos Santos, F.F., Da Cunha Jr, M.C., Marino, C.T. De Oliveira, C.A., 2015. Effect of a new device for sustained progesterone release on the progesterone concentration, ovarian follicular diameter, time of ovulation and pregnancy rate of ewes. Animal Reproduction Science 155, 56-63.
  • Driancourt, M., Webb, R. Fry, R., 1991. Does follicular dominance occur in ewes? Reproduction 93, 63-70.
  • Eppleston, J., Evans, G. Roberts, E., 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. Animal Reproduction Science 26, 227-237.
  • Gordon, I., 1997. Reproduction in sheep and goats. Controlled Reproduction in Farm Animals.  series 2.
  • Hameed, N., Khan, M.I.U.R., Ahmad, W., Abbas, M., Murtaza, A., Shahzad, M. Ahmad, N., 2020. Follicular dynamics, estrous response and pregnancy rate following GnRH and progesterone priming with or without eCG during non-breeding season in anestrous Beetal goats. Small Ruminant Research 182, 73-77.
  • Kimura, K., 2016. Superovulation with a single administration of FSH in aluminum hydroxide gel: a novel superovulation method for cattle. Journal of Reproduction and Development.
  • Kimura, K., Hirako, M., Iwata, H., Aoki, M., Kawaguchi, M. Seki, M., 2007. Successful superovulation of cattle by a single administration of FSH in aluminum hydroxide gel. Theriogenology 68, 633-639.
  • Koyuncu, M. Altıcekic, S.O., 2010. Effects of progestagen and PMSG on estrous synchronization and fertility in Kivircik ewes during natural breeding season. Asian-Australasian Journal of Animal Sciences 23, 308-311.
  • Langford, G., Marcus, G. Batra, T., 1983. Seasonal effects of PMSG and number of inseminations on fertility of progestogen-treated sheep. Journal of Animal Science 57, 307-312.
  • Quintero-Elisea, J.A., Macías-Cruz, U., Álvarez-Valenzuela, F.D., Correa-Calderón, A., González-Reyna, A., Lucero-Magaña, F.A., Soto-Navarro, S.A. Avendaño-Reyes, L., 2011. The effects of time and dose of pregnant mare serum gonadotropin (PMSG) on reproductive efficiency in hair sheep ewes. Tropical Animal Health and Production 43, 1567-1573.
  • Robinson, T.J., 1951. The augmentation of fertility by gonadotrophin treatment of the ewe in the normal breeding season. Journal of Agricultural Science 41, 6-38.
  • Scaramuzzi, R.J., Baird, D.T., Campbell, B.K., Driancourt, M.A., Dupont, J.,  Fortune, J.E., Gilchrist, R.B., Martin, G.B., McNatty, K.P., McNeilly, A.S., 2011. Regulation of folliculogenesis and the determination of ovulation rate in ruminants. Reproduction, Fertility and Development 23, 444-476.
  • Schipper, I.K., Hop, W.C. Fauser, B.C., 1998. The follicle-stimulating hormone (FSH) threshold/window concept examined by different interventions with exogenous FSH during the follicular phase of the normal menstrual cycle: duration, rather than magnitude, of FSH increase affects follicle development. The Journal of Clinical Endocrinology & Metabolism 83, 1292-1298.
  • SAS, 2002. SAS User’s Guide: Statistics. Version 9.1. SAS Institute Inc., Cary, North Carolina. USA.
  • Tríbulo, A., Rogan, D., Tribulo, H., Tribulo, R., Alasino, R.V., Beltramo, D., Bianco, I., Mapletoft, R.J. Bó, G.A., 2011. Superstimulation of ovarian follicular development in beef cattle with a single intramuscular injection of Folltropin-V. Animal Reproduction Science 129, 7-13.
  • Yahyaei, M., Mehrnejad, F., Naderi-Manesh, H. Rezayan, A.H., 2017. Follicle-stimulating hormone encapsulation in the cholesterol-modified chitosan nanoparticles via molecular dynamics simulations and binding free energy calculations. European Journal of Pharmaceutical Sciences 107, 126-137.
  • Yahyaei, M., Mehrnejad, F., Naderi-Manesh, H. Rezayan, A.H., 2018. Protein adsorption onto polysaccharides: Comparison of chitosan and chitin polymers. Carbohydrate Polymers 191, 191-197.
  • Zeleke, M., Greyling, J., Schwalbach, L., Muller, T. Erasmus, J., 2005. Effect of progestagen and PMSG on oestrous synchronization and fertility in Dorper ewes during the transition period. Small Ruminant Research 56, 47-53.
  • Zhang, Y. Yuan, X. A study of inducing estrus in virgin dairy goats during anestrous season.  Proceedings of the 11th International Congress on Animal Reproduction and AI. University College Dublin, Ireland, 1988.