[The effectiveness of intravaginal administration of estrumate for cows in silent heat in relation to the progesterone concentration in the blood].

In 22 silent heat cows with functional corpus luteum the blood progesterone concentrations and appearance of oestrus after administration of Estrumate were examined. 2 ml Estrumate (500 micrograms cloprostenol) were given intravaginally to 12 cows and intramuscularly to 10 cows respectively. Progesterone concentrations declined 32 hrs after application to levels below 3, 18 nmol/l in all animals. Within 10 days 66.6% of the cows after intravaginal administration of Estrumate and 70% after intramuscular administration came into oestrus. The results indicate that intravaginal application of Estrumate in silent cows with functional corpus luteum induced luteolysis and oestrus identical with intramuscular application.