J. Anim Sci.
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J. Anim Sci. 1974. 38:803-810.
© 1974 American Society of Animal Science
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Prediction of Age and Weight at Puberty in Beef Heifers1

G. F. Arije2 and J. N. Wiltbank3

Colorado State University, Fort Collins, and U.S.D.A.

Abstract

Data obtained over 4 years on puberty in 353 Hereford, Angus and Shorthorn heifers and their reciprocal crosses were analyzed by the least squares procedure for the effects of year of birth and breed of sire and dam on age (Age-P) and weight (Wt-P) at puberty, and for the regression of Age-P and Wt-P on birth date (B), actual weaning weight (W) and post-weaning average daily gain (A). Generalized predictive equations were obtained for Age-P and Wt-P. Predictive equations specific for each breed group for Age-P and Wt-P were also fitted. The predictive accuracies of four equations (two generalized and two for Angus heifers) were tested with two sets (Years I and II) of puberty data of unrelated Angus heifers. Age-P values predicted by equations 1 and 2 in Year I were similar but lower (P<.01) than observed values. The same was true of equations 8 and 9 for Wt-P in Year I. In Year II, Age-P predicted by equations 1 and 2 and Wt-P by equations 8 and 9 were not significantly different (P>.05) from observed values. Under situations where independent variables B, W, and A are normally distributed, these equations may be useful for predicting Age-P and Wt-P in Angus heifers.

Footnotes

1 Published with the approval of the Director of the Colorado State University Experiment Station as Scientific Series Paper No. 1866.

2 Present address: M.A.N.R., P.M.B. 5007, Ibadan, W.S., Nigeria.

3 The assistance of B. W. Knapp and Dr. T. M. Sutherland in the statistical analysis of the data is gratefully acknowledged.






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