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. 1995 Dec 1;36(4):393–400. doi: 10.1186/BF03547654

Acceleration and Timing of Fertile Ovulation in Cyclic Mares with a Deslorelin Implant

Påskyndande och förutsägande av ovulation hos sto med hjälp av ett deslarclinimplantat

A Gånheim 11,✉, A Gånheim 11, W Jöchle 21
PMCID: PMC8095403  PMID: 8669367

Abstract

In a blinded trial, the effectiveness and safety of 2.2 mg of the GnRH analog deslorelin acetate, administered in a short–term implant (STI) to normally cycling mares in estrus with a dominant ovarian follicle of 30 mm in diameter or larger, were evaluated, using a placebo implant as a negative control. A total of 39 mares received treatments at admittance with pre–randomized implants containing either 2.2 mg or 0 mg deslorelin. Mares were teased daily and examined rectally with ultrasound at 24 h intervals to determine time to Ovulation and duration of estrus. The number of breedings and the pregnancy rate at 18 (±3) and 38 (±3) days were recorded, as were systemic side effects and local reactions at the implantation sites. Pregnancies resulting from breedings during the treatment estrus and/or from breedings during the next estrus were followed and the early and late pregnancy loss rate, the number of pregnancies going to term and of live–born foals was recorded.

Mean follicle diameter at treatment was not significantly different between the deslorelin and placebo treatment group with 41.6 mm and 40.8 mm, respectively. Treatment with deslorelin STI reduced the time interval to Ovulation significantly from 69.5±25.48 h to 42.7±12.35 h (p<0.001). The percentage of mares having ovulated within 48 h rose from 26.3% to 95.0%, respectively, for placebo and deslorelin STI (p<0.001). As a consequence, the duration of estrus in days and the percent of animals requiring more than 1 breeding were significantly reduced in deslorelin treated animals from 5.4 days to 4.6 days, and from 55.6% to 5.0%, respectively (p=0.009 and =0.001). The percent of mares pregnant from breedings at the treatment estrus (65.0% versus 44.4%) or the next estrus (83.3% versus 92.3%) was satisfactory and similar for deslorelin and placebo treated mares (p>0.005), and in 70.0% and 66.7% of these once or twice bred mares did pregnancies go to term and live foals were born. kw|Keywords|k]GnRH

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Acknowledgments

Dr. Τ. J. Keefe, EnviroStat, Fort Collins, CO, USA, provided implant randomization and statistical evaluation of the clinical data. Mr. B. Svenson, ΒI–vet, Malmö, Sweden, assisted with the study permit and with drug importation. The study was sponsored by Peptide Technology, Ltd., Dee Why, NSW, Australia (Dr. Τ. E. Trigg).

References

  1. Cochran WG, Cox GM. Experimental Designs. 2nd. New York, NY, USA: John Wiley & Son, Inc.; 1975. [Google Scholar]
  2. Duchamp G, Bour B, Combarnous Y, Palmer E. Alternative solutions to hCG induction of Ovulation in the mare. J. Reprod. Fert., Suppl. 1987;35:221–228. [PubMed] [Google Scholar]
  3. Ginther OJ, Whitmore HL, Squires EL. Characteristics of estrus, diestrus and Ovulation in mares and effects of season and nursing. Amer. J. Vet. Res. 1972;33:1935–1939. [PubMed] [Google Scholar]
  4. Ginther OJ. Basic and applied aspects. Cross Plains, WI: Equiservices; 1992. Reproductive biology of the mare. [Google Scholar]
  5. Harrison LA, Squires EL, McKinnon AO. Comparison of HCG, buserelin and luprositol for induction of Ovulation in cycling mares. J. Equine vet. Sci. 1991;11:163–166. doi: 10.1016/S0737-0806(07)80039-6. [DOI] [Google Scholar]
  6. Henneke RD, Potter GD, Kreider JL, Yeates DF. Relationship between condition score, physical measurements and body fat percentage in mares. Equine vet. J. 1983;15:371–372. doi: 10.1111/j.2042-3306.1983.tb01826.x. [DOI] [PubMed] [Google Scholar]
  7. Klug Ε, Meinen Κ, Lepel J, Erbslöh J, Biet Κ, Lübekke Μ, Bader Η, Merkt Η, Jöchle W: Acceleration of Ovulation in the mare with a short–acting subcutaneous implant of the GnRH analog deslorelin. Proc. Internat. Congr. Anim. Re–prod., The Hague; 1992, 4, 1879–1881.
  8. Lamond DR, Buell JR, Stevenson WS. (1975) Efficacy of a Prostaglandin analogue in reproduction in the anoestrous mare. Theriogenology. 1975;3:77–85. doi: 10.1016/0093-691X(75)90017-5. [DOI] [PubMed] [Google Scholar]
  9. Loy RG, Hughes JP. The effects of human chor–ionic gonadotropin on Ovulation, length of estrus, and fertility in the mare. Cornell Vet. 1966;56:44–50. [PubMed] [Google Scholar]
  10. McKinnon AO, Nobelius AM, del Tarrida Marmol F S, Skidmore J, Vasey JR, Trigg TE. Predictable Ovulation in mares treated with an implant of the GnRH analogue deslorelin. Equine Vet. J. 1993;25:321–323. doi: 10.1111/j.2042-3306.1993.tb02972.x. [DOI] [PubMed] [Google Scholar]
  11. Meinert C, Silva JFS, Kroetz I, Klug, Trigg TE, Hoppen HO, Jöchle W. Advancing the time of Ovulation in the mare with a short–term implant releasing the GnRH analogue deslorelin. Equine Vet. J. 1993;25:65–68. doi: 10.1111/j.2042-3306.1993.tb02904.x. [DOI] [PubMed] [Google Scholar]
  12. Meyers PJ, Jöchle W, Samper JC, Sealey L, Conboy HS, Squires E, Reid MP, Bowman RT, Taylor BC, Gimenez T, Schlager R.L, Dimmick M.A: Efficacy of the GnRH analog, deslorelin, given as a short-acting subcutaneous implant, in accelerating Ovulation in the mare. Proc. Internat. Congr. Anim. Reprod., The Hague; 1992, 4, 1897–1899.
  13. Michel TH, Rossdale PD. Efficacy of human chor–ionic gonadotrophin and gonadotrophin releas–ing hormone for hastening Ovulation in Thoroughbred mares. Equine vet. J. 1986;18:438–442. doi: 10.1111/j.2042-3306.1986.tb03680.x. [DOI] [PubMed] [Google Scholar]
  14. Roser JF, Evans JW, Kiefer BL, Neely DP, Pacheco CA: Reproductive efficiency in mares with anti–hCG antibodies. Proc. 9th Int. Congr. Anim. Re–prod, and A.I., Madrid, Spain, 1980, 4, 627–630.
  15. Rossdale PD, Ricketts SW. Equine stud farm medicine. Philadelphia: Lea & Febiger; 1980. [Google Scholar]
  16. Shilova AV, Platov EM, Lebedev ST. The use of human chorionic gonadotropin for Ovulation date regulations in mares. Proe. VIII Int. Congr. Anim. Reprod. and AI (Krakow) 1976;3:204–207. [Google Scholar]
  17. Squires E. Personal communication; report on file. 1990. [Google Scholar]
  18. Squires EL, Harrison LA, McKinnon A O, Voss JL. 11th Internat. Congr. Animal Reprod. & A.I. 1988. Use of hCG, GNRH agonist or Prostaglandin analogue for induction of Ovulation in mares; p. 460. [Google Scholar]
  19. Squires EL, Moran DM, Farlin ME, Jasko DJ, Keefe TJ, Meyers SA, Figueiredo E, McCue PM, Jöchle W. Effect of dose of GnRH analog on Ovulation in mares. Theriogenology. 1994;41:757–769. doi: 10.1016/0093-691X(94)90185-L. [DOI] [PubMed] [Google Scholar]
  20. Sullivan JJ, Parker WG, Larson LL. Duration of es–trus and Ovulation time in non-lactating mares given human chorionic gonadotropin following its repeated injection in the cyclic mare. J. Reprod. Fert. Suppl. 1973;27:173–179. [Google Scholar]
  21. Voss JL, Sullivan JJ, Pickett BW, Parker WG, Bur–wash LD, Larson LL. The effect of hCG on duration of oestrus, Ovulation time and fertility in mares. J. Reprod. Fert., Suppl. 1975;25:297–301. [PubMed] [Google Scholar]
  22. Wilson CG, Downie CR, Hughes JP, Roser JF. Effects of repeated hCG injections on reproductive efficiency in mares. Equine Vet. Sci. 1990;10:301–308. doi: 10.1016/S0737-0806(06)80015-8. [DOI] [Google Scholar]

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