J. Anim Sci.
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J. Anim Sci. 1984. 58:1090-1096.
© 1984 American Society of Animal Science
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Comparison of an Animal Model and an Equivalent Reduced Animal Model for Computational Efficiency Using Mixed Model Methodology

H. T. Blair1 ,2, 3, and E. J. Pollak4

Cornell University, Ithaca, NY 14853

Abstract

Sheep data from a flock selected for increased 14-mo greasy fleece weight were used in a comparison for rate of convergence for equations from two models. The models compared were the individual animal model and an equivalent reduced animal model. The equations for the reduced animal model were the same as those obtained if the equations for nonparents in the animal model were absorbed. These models allowed for the evaluation of animals to include their own as well as relatives' records. Animals were evaluated simultaneously for three traits: greasy fleece weight, live weight and mean fiber diameter. Converged solutions were reached in approximately one-half the number of rounds using the reduced animal model. Adequate ranking of animals for selection purposes was achieved in 100 rounds; however, a representative picture of genetic trend required further iteration.

Footnotes

1 Appreciation is extended to Professor A. L. Rae of the Anim. Sci. Dept. Massey Univ., New Zealand, for his foresight in establishing the flocks from which the data used in this analysis were derived. The work of farm and technical staff in maintaining the flocks and collecting data is also gratefully acknowledged.

2 Financial assistance from the Claude McCarthy Foundation (New Zealand) enabled Dr. H. T. Blair to undertake 12 mo research leave at Cornell Univ.

3 Dept. of Anim. Sci., Massey Univ., Palmerston North, New Zealand.

4 Dept. of Anim. Sci.






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Copyright © 1984 by the American Society of Animal Science.