title: Controlled breeding of sheep for studies in fetal physiology.
abstract: A supply of fetal sheep of known gestational age was ensured after synchronizing estrus in the ewes, by means of an intravaginal pessary impregnated with a progestagen. Estrus occurred approximately 2 days after the pessary was removed. Conception rates at different times of the year and for a period of 4 years were described.
mesh_terms: D000818:Animals; D001947:Breeding; D004973:Estrus Synchronization; D005260:Female; D005306:Fertilization; D005333:Fetus / Q000502:physiology*; D008297:Male; D011247:Pregnancy; D012756:Sheep / Q000502:physiology*