FATTENING PERFORMANCE AND CARCASS QUALITY OF BULLS OF THE BLACK-PIED DAIRY-CATTLE UNDER THE INFLUENCE OF THE ACTIVE-SUBSTANCE ZERANOL

Within a trial 40 Black-Pied bulls have been treated with Zeranol up t o four times. Using stage slaughtering their growth performance, carca ss composition and meat quality have been compared with 40 untreated b ulls acting as controls.An effect of Zeranol on the development of the primary and secondary sex characteristics as well as the surface shar e of microscopically small fibres of the connective tissue in the musc ulus longissimus dorsi was provable. There was a small influence on th e growth performance, the energy efficiency, the carcass quality and q uality of the lean meat. The excretion of Zeranol within the excrement s beyond the waiting period indicated that the decomposition of the im plants is different for each animal.