Document Type

Thesis - Open Access

Award Date


Degree Name

Doctor of Philosophy (PhD)


Animal Science


The production and marketing of meat is the world’s largest agriculturally related industry in terms of employment and gross product value. Thirty-one billion pounds or 30 percent of the total world supply of all types of meats, including poultry products, were consumed in the United States during 1963. Approximately 45 percent of this meat was beef and an additional 2.7 percent was veal. In order to retain the present advantage, all phases of the beef industry must continually search for improvements in production and marketing practices which would reduce the cost per edible unit or increase the quality of the product. Although considerable room for improvement still exists, progress has been realized in selection for conformation and weight. Various nutritional and management procedures are also continually being tested and recommended for practice. The variations in carcass composition and yield are readily apparent in every packing plant. The amount of genetic progress realized through direct or mass selection is dependent on the proportion of the total variance that is attributable to linear gene effects. This is termed heritability. Subjective scores for the entire animal and component parts of the animal have been used as predictors of both slaughter and breeding value for many years. Variations in the physiological manifestations within the animal have not been thoroughly studied in relation to carcass composition or growth rate. There are many qualitative traits which are dependent on the gene action. In some of these, the metabolic pathway affected by the gene or gene complement has been identified. Since the various blood constituents are highly important in tissue production, nutrition, protection, and homeostasis, the study of certain circulation components may provide some insight into the physiological differences which are involved with variations in growth rate and body composition.

Library of Congress Subject Headings

Beef cattle -- Breeding


Includes bibliographical references



Number of Pages



South Dakota State University