Oestrogen-progesterone relationships in the induction of oestrus in spayed heifers.
D000818:Animals; D002369:Castration; D002417:Cattle; D002490:Central Nervous System / Q000187:drug effects; D004357:Drug Synergism; D004958:Estradiol / Q000008:administration & dosage*; D004971:Estrus / Q000187:drug effects*; D005260:Female; D011247:Pregnancy; D011374:Progesterone / Q000008:administration & dosage*; D013997:Time Factors
D011374:Progesterone; D004958:Estradiol