プロスタグランジソF<SUB>2α</SUB>, エストロジェンおよびコルチコイドの妊娠牛に対する流・早産および促進分娩効果

Abstract

Induction of parturition was examined in fattening Holstein cows at various stages of pregnancy. Abortion was induced in most of cows administered with PGF2α at the early stage of pregnancy (1-4 months). Parturition was hardly accelerated in cows administered with PGF2α alone at the advanced stage of pregnancy (approximately5 months and later). Subsequent administration of estradiol with dexamethasone after the first PGF2α treatment caused abortion within 2-4 days. When it was not enough to cause abortion, further injection with dexamethasone, estrogens and PGF2α was required for abortion to occur in cows at the advanced stage of pregnancy.Parturition could always be induced artificially in cows at the advanced stage of pregnancy within 2-4days after the final treatment, although retained placenta was frequently observed in these cows.