The effect of sex condition and growth implants on bovine muscle fiber characteristics.

Steers, bulls and bulls implanted with Synovex-S or Ralgro were slaughtered at 12 and 16 months of age. With increasing animal age, the percentage of intermediate fibers decreased while the percentage of white fibers increased. The area of all fibers increased with increasing age. Bulls had a higher percentage of red fibers, larger red and intermediate fibers and a higher percentage area of red and intermediate fibers compared with steers. Implanted bulls were generally intermediate to intact bulls and steers in muscle fiber type characteristics. Carcass fat measurements and tenderness ratings were positively correlated to the percentage of white muscle fibers and negatively correlated to the percentage of intermediate fibers. Carcass characteristics and sensory properties of meat are discussed in relation to muscle fiber characteristics.