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 to four times. Using stage slaughtering their growth performance, carcass composition and meat quality have been compared with 40 untreated bulls acting as controls. An effect of Zeranol on the development of the primary and secondary sex characteristics as well as the surface share of microscopically small fibres of the connective tissue in the musculus longissimus dorsi was provable. There was a small influence on the growth performance, the energy efficiency, the carcass quality and quality of the lean meat. The excretion of Zeranol within the excrements beyond the waiting period indicated that the decomposition of the implants is different for each animal.