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Journal of Dairy Science Vol. 63 No. 1 133-140
© 1980 by American Dairy Science Association ®
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Variation of Traits of a Mating Appraisal Program1

J. R. Thompson, A. E. Freeman and P. J. Berger

Department of Animal Science, Iowa State University, Ames 50011

ABSTRACT

Data from Mating Appraisal for Profit of Midwest Breeders Cooperative were analyzed for a model with evaluator, herd, parity, sire, linear days milked, quadratic days milked, interaction of evaluator by parity, and residual. Parity affected all traits except basic form and legs. Evaluators interacted with parity, and sires affected all traits. All traits except front were affected by quadratic days milked and all traits by linear days milked. Heritabilities from paternal half sisters were basic form .96, scale .55, front .34, body .42, back .13, legs .14, feet .16, rump .13, rear udder .13, fore udder .14, center support .14, and teats .19. The heritability of basic form may be inflated by sire identification prior to scoring. Traits in close physical proximity showed genetic correlations in excess of .50; those not in close proximity showed smaller or negative correlations. Correlations with basic form showed that thicker cows score superior for correlated traits. Subcodes were used for seven of the traits in the program. Heritabilities for subcodes generally were small, ranging from .00 to .15 with most less than .10. Changes in conformation can result from selection, but selection on specific faults (subcodes) will not yield changes quickly.

FOOTNOTES

1 Journal Paper No. J-9328 of the Iowa Agriculture and Home Economics Experiment Station, Ames. Project No. 1053.






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Copyright © 1980 by the American Dairy Science Association ®.