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U. S. Department of Agriculture
Abstract
Data of eight meat production characters and nineteen body measurements from 101 beef Shorthorn steers and 62 Milking Shorthorn steers raised at the Beltsville Agricultural Research Center were used to study realtionships between these characters and the measurements. Since the material was from two different breeds, the variance and covariance caused by breed differences were calculated and subtracted from the total variances and covariances to increase the homogeneity of the data.
All the eight meat production characters and nineteen body measurements were divided into eight main groups and two subgroups. Characters or measurements within each group or subgroup were in general well correlated with each other. Each body measurement group could be represented fairly well by one measurement which was highly correlated with all the other measurements within the group. Height at withers was the best for the height measurement group, length of body for the length measurements, width of muzzle for the head measurements, width at chest for the width measurements, and circumference at navel for the circumference measurements. Depth of chest was well correlated with all the circumference measurements and could be included in the circumference group instead of the height group. Length of rump could be included in the width group rather than the length group.
All the width and circumference measurements were positively correlated with slaughter grade, carcass grade and dressing percentage, and could be called fleshing measurements. All the height and length measurements were negatively correlated with slaughter grade and could be called skeletal measurements. Birth weight had positive correlations with most of the height and length measurements but negative correlations with the width measurements. It was thus similar to the skeletal measurements. A higher birth weight tended to go with less days to weaning, less days to final weight and poorer beef characters, but it also tended to go with a greater daily gain and higher efficiency in feed utilization than a lower birth weight.
Measurements of head, width and circumference had negative correlations with efficiency of feed utilization and average daily gain. This indicated that a steer with a small head, narrow body and small body circumference would have a better efficiency and daily gain when all steers were measured at 900 pounds than one with a larger head, wider body and larger body circumference.
Significant multiple correlations between the beef characters and some body measurements were obtained. Formulas for calculating indices for the beef characters were derived on the basis of the relationships between the beef characters and their closely correlated body measurements.
1 Guest research scientist from China.
2 Animal Husbandman, U. S. Department of Agriculture.
Acknowledgment—The authors wish to acknowledge the help of Dr. R. G. Schott, Bureau of Animal Industry, in reading and criticizing the manuscript; and to acknowledge the help of the late W. H. Black and O. G. Hankins for general supervision of the production and meats phases of the project, respectively. For cooperation in grading the cattle and carcasses, acknowledgement is also made to L. B. Burk (retired), C. E. Murphey, and M. T. Foster (transferred to the Office of Foreign Agricultural Relations) of the Livestock Branch, Production and Marketing Administration, to R. L. Hiner and M. W. Hazen of the Bureau of Animal Industry and to Bradford Knapp, Jr., formerly of the Bureau of Animal Industry and now with the U. S. Technical Cooperation Administration, Cairo, Egypt, as a livestock breeding specialist. Dr. Hiner also supervised the slaughtering of the cattle and determination of the dressing percentages.
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