Induction of Parturition in Cows at Various Stages of Pregnancy by Administration with PGF Alone or a Combination of Estrogens and Corticoid

Abstract

Induction of parturition was examined in fattening Holstein cows at various stages of pregnancy. Abortion was induced in most of cows administered with PGF_2α at the early stage of pregnancy (1-4 months). Parturition was hardly accelerated in cows administered with PGF_2α alone at the advanced stage of pregnancy (approximately5 months and later). Subsequent administration of estradiol with dexamethasone after the first PGF_2α treatment caused abortion within 2-4 days. When it was not enough to cause abortion, further injection with dexamethasone, estrogens and PGF_2α 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.