U.S. Department of Agriculture: Agricultural Research Service, Lincoln, Nebraska


Date of this Version


Document Type



Published in Beef Research Program Progress Report (1988) No. 3: 52-53


Growth and development of meat-producing animals involves a complex integrated system of changes in the structure and mass of body tissues. Researchers have observed and documented that meat animal growth and development may be altered through the diet or alteration of the sex condition. Most significant alterations are in rates of deposition of protein, fat, and connective tissue, as well as the palatability of the cooked meat. Changes in wt of cattle beyond 14 mo of age have been largely associated with the fat deposition in the body. Studies have shown that youthful bulls have advantages in performance of growth and leanness and disadvantages in tenderness when compared with steers. Differences in tenderness have been attributed to variations in fatness and in connective tissue. Connective tissue has been reported to increase markedly at about 12 mo of age and to decrease in solubility with age. These agerelated changes in connective tissue also have been reported to be more pronounced in bulls than steers.

It appears that, as steers are fed dietary energy above maintenance, body protein accretion increases. The alteration in protein content is associated with improved product tenderness. Growth rate over a short period may be a more important determinant of tenderness than the length of time that cattle are fed a high-energy diet. Proteolytic enzymes are needed to increase protein turnover, and these enzymes may also influence postmortem changes in meat properties. Animals gaining or losing wt may alter these enzyme profiles. Therefore, a strong possibility exists that protein turnover is increased and a more youthful connective tissue present during wt gain. This experiment was undertaken to determine the effects of change in body wt on body tissue development and meat quality from youthful bulls.