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Heritability of Growth, Beef Characters and Body Measurements in Milking Shorthorn Steers

Abstract

Heritability estimates were obtained for five growth characters, three beef characters and nineteen body measurements from 58 Milking Shorthorn steers raised at the Agricultural Research Center, Beltsville, Maryland, from 1943 through 1949. All steers were slaughtered at a live weight of approximately 900 lb. Component variances for each character were computed and the paternal half-sib correlation method was used to estimate the heritability coefficients.

Estimates of the percent heritability of the growth characters ranged from 3.2 to 56.6 percent. Of these five growth characters, birth weight, days to weaning and days to final weight were of high heritability and showed more possibility of being improved by selection than the others. All the three beef characters, slaughter grade, carcass grade and dressing percentage, were of high heritability and the prospects for their improvement by selection appear to be good. Of the nineteen body measurements, height at withers, width between eyes, width of muzzle and depth of chest had high heritabilities of 40.1 to 65.5 percent. Height at floor chest, height at flank, circumference at foreflank, circumference at shin bone and all the width measurements except width at shoulder had heritabilities varying from 4.5 to 33.5 percent. The three length measurements, circumference measurements at navel and at rear flank, length of nose and width of shoulder had zero heritability.

All the twenty-seven characters were divided into four groups: ten characters were of high heritability (40.1–69.1 percent); three characters of medium heritability (32.3–33.5 percent); six of low heritability (3.2–18.8 percent); and eight, of no-heritability (0–0.5 percent).

¹ Animal Husbandman, U. S. Department of Agriculture.

² Research Collaborator at U. S. Department of Agriculture.

The authors wish to acknowledge the help of Dr. R. G. Schott, Animal and Poultry Husbandry Research Branch, in reading and criticizing the manuscript. For cooperation in grading the cattle and carcasses, acknowledgment is also made to L. B. Burk (retired), C. E. Murphy, and M. T. Foster (transferred to Office of Foreign Agricultural Relations) of the Livestock Branch, Production and Marketing Administration, and to O. G. Hankins (deceased), R. L. Hiner, and M. W. Hazen of the Animal and Poultry Husbandry Research Branch. Dr. Hiner also supervised the slaughtering of the cattle and determined the cold carcass weights.