[Use of megesterol acetate for synchronization of estrus in cows]

Megestrol acetate has proved to be of positive impact upon synchronisation of oestrus in beef cows. Fodder-borne administration of 35-45 mg megestrol acetate caused oestrus in nursing cows, accompanied by disorders in ovarian function. The physiological condition of the animal at the date of treatment was found to be of major relevance to success. Evidence was produced to the strong action of serum obtained from pregnant mares in which the ratio of total gonadotrophic activity to luteinising activity was between 3:1 and 2.5:1. The use of megestrol acetate is recommended as a method by which to activate sexual function in the context of beef cattle breeding.