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Journal of Dairy Science Vol. 68 No. 11 2989-2994
© 1985 by American Dairy Science Association ®
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Components of Genetic Variance and Covariance for Linear Type Traits in Jersey Cattle1

C. L. Thomas, W. E. Vinson and R. E. Pearson

Department of Dairy Science, Virginia Polytechnic Institute and State University, Blacksburg 24061

H. D. Norman

Animal Improvement Programs Laboratory, Agricultural Research Service, United States Department of Agriculture, Beltsville, MD 20705

ABSTRACT

First available appraisals for 67,644 Jersey cows were used to estimate relative magnitudes of additive and selected sources of nonadditive genetic variance and covariance for 13 type traits scored linearly from 50 to 99 points.

Covariances among four types of relatives were used to estimate components of genetic variance and covariance for each of the 13 traits. Direct additive, direct dominance, and additive maternal genetic variances and the direct-maternal additive genetic covariance were estimated using covariances among paternal half-sibs, full-sibs, daughters and dams, and maternal half-sibs.

Estimates of additive genetic variance were 11 to 36% of variance within herd-appraiser subclasses with largest values for stature, strength, rump angle, rump width, and udder depth. Dominance components were two to four times the magnitude of additive components for dairy character, rump width, fore udder, rear udder height, rear udder width, and suspensory ligament but much smaller for other traits. Maternal effects and the direct-maternal additive genetic covariance appeared small for all linear type traits.

FOOTNOTES

1 Partially supported by a grant from the American Jersey Cattle Club.






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Copyright © 1985 by the American Dairy Science Association ®.