title: The interrelationship between anti-Müllerian hormone, ovarian follicular populations and age in mares.
abstract: BACKGROUND
  Anti-Müllerian hormone (AMH) is a granulosa-cell-derived glycoprotein, which plays an important inhibitory role during folliculogenesis. Concentrations of AMH are highly correlated with antral follicle counts (AFCs) in other species, which in turn are related to follicular reserve. Relatively little is known about AMH and AFC in the mare.
  
  
  OBJECTIVE
  To determine plasma AMH concentrations and AFCs in mares of different ages, to measure the repeatability of AMH concentrations and AFCs within and across oestrous cycles and to assess the relationship between plasma AMH concentrations and AFCs with regard to mare age and follicle size.
  
  
  METHODS
  An observational study examining the relationship between AMH, AFC and age in 45 mares.
  
  
  METHODS
  Young (3-8 years), middle-aged (9-18 years) and old mares (19-27 years) were examined by transrectal ultrasonography over 2 or 3 oestrous cycles. Plasma AMH concentrations and AFCs were determined, and antral follicles were classified by size into different groups.
  
  
  RESULTS
  Plasma AMH concentrations varied widely between mares within similar age groups. Antral follicle counts were significantly lower in old mares than in young and middle-aged mares, and AMH concentrations were significantly lower in old than in middle-aged mares. A positive relationship was detected between AFC and AMH, and this relationship varied by mare age with a strong correlation in older mares (ρ = 0.86; P<0.0001), a moderate correlation in middle-aged mares (ρ = 0.60; P = 0.01) and no correlation in young mares (ρ = 0.40, P<0.4). The AMH concentrations were significantly related to the number of antral follicles between 6 and 20 mm in diameter, and the repeatability of AFCs and AMH concentrations was high within and between oestrous cycles.
  
  
  CONCLUSIONS
  Our findings indicate that the relationship between AMH and AFC varies across age groups, and concentrations of AMH might be a better reflection of reproductive age than calendar age.
authors.affiliation: Gluck Equine Research Center, Department of Veterinary Science, University of Kentucky, Lexington, USA.
authors.forename: A
authors.initials: A
authors.lastname: Claes
authors.affiliation: Gluck Equine Research Center, Department of Veterinary Science, University of Kentucky, Lexington, USA.
authors.forename: B A
authors.initials: BA
authors.lastname: Ball
authors.affiliation: Gluck Equine Research Center, Department of Veterinary Science, University of Kentucky, Lexington, USA.
authors.forename: K E
authors.initials: KE
authors.lastname: Scoggin
authors.affiliation: Gluck Equine Research Center, Department of Veterinary Science, University of Kentucky, Lexington, USA.
authors.forename: A
authors.initials: A
authors.lastname: Esteller-Vico
authors.affiliation: Gluck Equine Research Center, Department of Veterinary Science, University of Kentucky, Lexington, USA.
authors.forename: J J
authors.initials: JJ
authors.lastname: Kalmar
authors.affiliation: Department of Population Health and Reproduction, School of Veterinary Medicine, University of California, Davis, USA.
authors.forename: A J
authors.initials: AJ
authors.lastname: Conley
authors.affiliation: Gluck Equine Research Center, Department of Veterinary Science, University of Kentucky, Lexington, USA.
authors.forename: E L
authors.initials: EL
authors.lastname: Squires
authors.affiliation: Gluck Equine Research Center, Department of Veterinary Science, University of Kentucky, Lexington, USA.
authors.forename: M H T
authors.initials: MH
authors.lastname: Troedsson
mesh_terms: D000375:Aging / Q000502:physiology*; D000818:Animals; D054304:Anti-Mullerian Hormone / Q000097:blood / Q000378:metabolism*; D030762:Estrous Cycle / Q000502:physiology; D005260:Female; D006736:Horses / Q000502:physiology*; D006080:Ovarian Follicle / Q000502:physiology*
chemical_list: D054304:Anti-Mullerian Hormone
keywords: age; anti-Müllerian hormone; antral follicle count; horse; mare; ovarian reserve