served by high dose levels. More work is in progress in order to select the most effective steroid combination as well as the appropri- ate dose levels for optimal synchronization and ferti- lity. Literature: Jochle, W. "Der prakt. Tierarzt", 45 (1964) Jochle, W., Schilling, E., Smidt, D., Fiedler, E., "Zuchthygiene", 2, 122-127 (1967) Smidt,D., Sympos. Phys. Path. Fortpfl. Haustiere, Miinchen (1968) Witt, M., "Zschr. Tierziicht. Ziichtungsbiol.", 84, 192-200 (1968) Zerobin, K., "Zschr. Tierziicht. Ziichtungsbiol.", 84, 341-348 (1968)