J. Anim Sci.
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J. Anim Sci. 1957. 16:217-223.
© 1957 American Society of Animal Science
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A Genetic Study in Steer Progeny Groups during Successive Growth Periods1

J. Urick2, A. E Flower, F. S. Willson3 and C. E. Shelby4

Montana Agricultural Experiment Station

Abstract

The relationships between three successive growth periods in 205 high grade Hereford steer calves from 23 sire groups were studied at the North Montana Branch Station at Havre. The periods were first winter on a moderate fattening ration, second summer on the mountain range, and second winter on a fattening ration. The mean daily gains in pounds for the periods were as follows: first winter, 1.88; second summer on grass, 1.82; and second winter, 1.93.

Winter gains were extremely highly correlated genetically (+0.99). Gains on summer range were highly correlated with first (+0.45) and second winter (+0.87) periods. Selection in any one period should result in some genetic gain in the others. Maximum production would probably be obtained if selections were done in the period and nutritional regime for which the commercial stock were intended.

The following estimates of heritability were obtained by paternal half-sib correlations: first winter on moderate fattening ration, 0.34, second summer on grass, 0.43, and second winter on a fattening ration, 0.09.

Footnotes

1 Contributions from the Western Regional Project W-l, "The Improvement of Beef Cattle Through the Application of Breeding Methods." Acknowledgment is made to L. N. Hazel for assistance in setting up the analysis of these data, and to Bernard Ostle and the Montana State College Statistical Laboratory in performing a number of the computations. Published with approval of the Director of the Montana Agricultural Experiment Station Journal Series No. 367.

2 North Montana Branch Station.

3 Montana Agricultural Experiment Station, Department of Animal Industry and Range Management, Bozeman.

4 A.R.S., U.S.D.A.






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Copyright © 1957 by the American Society of Animal Science.