THE EFFECTS OF BREED OF SIRE AND POSTMORTEM AGING UPON CERTAIN HISTOLOGICAL PROPERTIES OF TWO BOVINE MUSCLES

ABSTRACT A total of 104 longissimus dorsi (LD) and 36 semitendinosus (ST) muscles from carcasses from three different breeds of sire groups (Charolais, Simmental, and Chianina) were sampled for histological evaluation. LD muscles were sampled and evaluated after 5 different postmortem intervals (1, 24, 144, 312, and 480 h), while ST muscles were sampled and evaluated after 3 different postmortem intervals (144, 312, and 480h). The composite result of this study indicate that Chianina bred carcasses had more contracted LD fibers than Charolais bred carcasses; and that Simmental bred car had larger ST muscle fibers than Charolais and Chianina bred es. Indications were also obtained that Simmental bred ca to have a higher proportion of wavy ST and LD fibers, than their nterparts from Chianina bred and Charolais bred carcasses, ly. In addition, postmortem aging appeared to progressively the ease with which both LD and ST muscle fibers could be frag. ST muscle fibers also appeared to become less contracted during while LD muscle fibers were the most contracted prerigor and after aging.