The purpose of this research was to determine; (a) the difference in paiatabiiity between bulls and steers of three frame sizes fed to three different end-points; (b) cholesterol and fatty acid composition of bulls and steers based on lipid content and time on feed; (c) degradation of myofibrils isolated from dark cutting and normal pH beef and (d) utilization of ultrasound variables as they relate to sensory attributes of longisslmus thoracis muscle. Explanation of Thesis Format This thesis consists of a general introduction, literature review, three publishable papers and a concluding summary. The papers represent the work done by the first author to fulfill requirements for the degree of Doctor of Philosophy. Co-authors were involved in the review for each paper. Each paper consists of a title page, abstract, introduction, materials and methods, results and discussion, conclusion and references. The format of the papers is in accordance with the Journal of Food Science style guide for research papers.