INVESTIGATIONS ON GROWTH OF BIOTECHNOLOGI CAL PRODUCED BEEF-CATTLE TWINS

Growth performance of life weight, body size, tissues as well as muscl e structure trails were investigated on 29 male and 28 female beef cat tle twin calves and 36 male and 29 female single calves respectively. The proportion of Charolais and Simmenthal breeds in the investigated cattle varied between 75 and 100%. All calves derived from primipara c alvings. Growth performance of twins was inferior to singles. There we re only small differences in carcass composition and quality between t wins and singles. Muscle structure traits can give a good explanation for the inferior muscle growth of twins. Corresponding to inferior car cass weights and a lower meat protein yield twins had smaller muscle f ibre diameters in musculus longissimus dorsi. In agreement with partia lly lower pH and higher values for meat color brightness twins had evi dently a higher proportion of fast twitch fibres with mainly glycolyti c metabolism.