title: Control of breeding in the mare.
abstract: Six mares were studied over a period of two years under varying conditions of lighting from total darkness to normal ambient lighting. The mares continued to cycle during the winter under natural lighting and also when kept in total darkness. Circulating melatonin, progesterone and oestrogen concentrations were determined and related to clinical changes in the reproductive tract.
mesh_terms: D000780:Anestrus / Q000502:physiology; D000818:Animals; D004971:Estrus / Q000502:physiology*; D005260:Female; D006736:Horses / Q000502:physiology*; D008027:Light; D008550:Melatonin / Q000097:blood; D011247:Pregnancy; D011270:Pregnancy, Animal / Q000502:physiology*; D011374:Progesterone / Q000097:blood; D012726:Sexual Behavior, Animal / Q000502:physiology*
chemical_list: D011374:Progesterone; D008550:Melatonin