J. Anim Sci.
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J. Anim Sci. 1953. 12:552-560.
© 1953 American Society of Animal Science
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Repeatability of Production in Range Beef Cows1

M. P. Botkin2 and J. A. Whatley, Jr.

Oklahoma Agricultural Experiment Station

Abstract

IN order to estimate the effectiveness of selection for production, it is necessary to know the repeatability of the traits which measure production. Also, repeatability of the traits must be known in order to compare accurately the producing ability of cows with varying numbers of records. In experimental work where group comparisons are made, repeatability estimates are very useful in order to determine the best method of allotment.

Knapp et al. (1942) estimated that about 19 percent of the variance in birth weight and about 20 percent of the variance in weaning weight were due to differences between cows. Koger and Knox (1947) found an average correlation of 0.49 between weaning weights of all adjacent calves by the same cow, and of 0.24 between grades of first and second calves. Gregory et al. (1950) determined the correlation and regression between first and second, first and third, and second and third records for weaning weight, birth weight, and gain from birth to weaning. Estimates of repeatability ranged from 0.35 to 0.50 for weaning weight, from 0.38 to 0.57 for gain from birth to weaning, and from – .12to 0.24 for birth weight. Koch (1951) determined the intraclass correlation between weaning weights of calves by the same cow. His estimate of the portion of the variance in weaning weights which was due to permanent differences between cows was 0.52.

Footnotes

1 Animal Husbandry Department, Stillwater, Oklahoma.

2 Now with the Animal Production Department, University of Wyoming, Laramie, Wyoming.






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Copyright © 1953 by the American Society of Animal Science.