title: Ovarian function and pregnancy outcome in pony mares following immunocontraception with native and recombinant porcine zona pellucida vaccines.
abstract: BACKGROUND
  Few studies have investigated ovarian function in the mare undergoing porcine zona pellucida (pZP) immunocontraception despite reported ovarian dysfunction in other species.
  
  
  OBJECTIVE
  This study aimed to describe ovarian function and oestrous cyclicity in pony mares following treatment with either the conventional pZP vaccine or a novel recombinant form of the vaccine derived from porcine ZP3 and ZP4 (reZP). In addition, the contraceptive efficacy of pZP vs. reZP was assessed.
  
  
  METHODS
  Blinded, randomised, prospective clinical trial.
  
  
  METHODS
  Mares (n = 21) were randomised into 3 groups of 7: Group I received the pZP vaccine, with a booster 5 weeks later; Group II received the reZP vaccine, with a booster 5 weeks later; and Group III (controls) received 2 treatments, 5 weeks apart, of saline and adjuvant alone. Mares underwent weekly monitoring via transrectal palpation and ultrasound examination of the reproductive tract, with daily monitoring during oestrus. Data were collected over a 24 week period coinciding with the physiological breeding season; treatments commenced in Week 4. Serum samples were obtained for antibody titres and ovarian steroid level analyses at 7 day intervals. Cycling mares were bred via fresh semen artificial inseminations over a maximum of 2 consecutive oestrous cycles, commencing 5 weeks post booster vaccination.
  
  
  RESULTS
  Control mares cycled throughout the trial. After treatment, 6 of 7 pZP mares (86%) and one reZP mare (14%) had an extended anoestrus that correlated with basal serum oestradiol and progesterone levels. All mares resumed cyclicity by 10 months post treatment. Pregnancies were diagnosed in all controls, 4 reZP- (57%) and none of the pZP-immunised mares.
  
  
  CONCLUSIONS
  The current study demonstrates the reversible suppression of ovarian function in pony mares following treatment with pZP. The effect of the reZP vaccine on pregnancy outcome requires further investigation.
authors.affiliation: Section of Reproduction, Department of Production Animal Studies, Faculty of Veterinary Science, University of Pretoria, Onderstepoort, South Africa.
authors.forename: C J
authors.initials: CJ
authors.lastname: Joonè
authors.affiliation: Section of Reproduction, Department of Production Animal Studies, Faculty of Veterinary Science, University of Pretoria, Onderstepoort, South Africa.
authors.forename: H J
authors.initials: HJ
authors.lastname: Bertschinger
authors.affiliation: Reproductive Cell Biology Laboratory, National Institute of Immunology, New Delhi, India.
authors.forename: S K
authors.initials: SK
authors.lastname: Gupta
authors.affiliation: Department of Production Animal Studies, Faculty of Veterinary Science, University of Pretoria, Onderstepoort, South Africa.
authors.forename: G T
authors.initials: GT
authors.lastname: Fosgate
authors.affiliation: Reproductive Cell Biology Laboratory, National Institute of Immunology, New Delhi, India.
authors.forename: A P
authors.initials: AP
authors.lastname: Arukha
authors.affiliation: Reproductive Cell Biology Laboratory, National Institute of Immunology, New Delhi, India.
authors.forename: V
authors.initials: V
authors.lastname: Minhas
authors.affiliation: University of Utrecht, The Netherlands.
authors.forename: E
authors.initials: E
authors.lastname: Dieterman
authors.affiliation: Section of Reproduction, Department of Production Animal Studies, Faculty of Veterinary Science, University of Pretoria, Onderstepoort, South Africa.
authors.forename: M L
authors.initials: ML
authors.lastname: Schulman
mesh_terms: D000818:Animals; D000906:Antibodies / Q000097:blood; D003269:Contraception, Immunologic / Q000662:veterinary*; D004958:Estradiol / Q000097:blood; D005260:Female; D010053:Ovary / Q000502:physiology*; D011247:Pregnancy; D011256:Pregnancy Outcome; D011270:Pregnancy, Animal; D011374:Progesterone / Q000097:blood; D013552:Swine; D022642:Vaccines, Contraceptive / Q000276:immunology*; D015044:Zona Pellucida / Q000276:immunology*
chemical_list: D000906:Antibodies; D022642:Vaccines, Contraceptive; D011374:Progesterone; D004958:Estradiol
keywords: anoestrus; artificial insemination; horse; oestradiol; ovarian function; progesterone