[Studies on the use of megestrol acetate for estrus synchronization in heifers]

Megestrol acetate has been tested for its applicability to synchronisation of oestrus in 463 mature heifers in the framework of preclinical and clinical experiments. Clinical tests and studies in the context of laboratory diagnostics have shown that 40 mg/die megestrol acetate, administered in two applications with twelve hours in-between and over 15 days, are necessary for maximum synchronisation effect. The resulting oestrus was found to be prolonged, with ovulations taking place within two or three days. Technological requirements in this context are discussed. Megestrol acetate is found to be suitable for oestrus synchronisation in heifer. Tests conducted under industrialised conditions have shown conception rates to be identical with those obtained by administration of chloromadinone acetate.