A Genetic Study in Steer Progeny Groups during Successive Growth Periods

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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. Copyright © . .

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