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Journal of Dairy Science Vol. 67 No. 2 372-379
© 1984 by American Dairy Science Association ®
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Relationships between Linearly Scored Components of Type and Final Score of Jersey Cows1

C. L. Thomas, W. E. Vinson, R. E. Pearson and B. G. Cassell

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

E. P. Barton

American Jersey Cattle Club, Columbus, OH 43227

ABSTRACT

Evaluations for final score and 13 components of type, scored linearly from 50 to 99 points, for 27,635 Jersey cows were used to assess the relative importance of linear traits in determining final score. Relationships between final score and several linear traits differed by age at classification, necessitating analyses within age groups. Age groups were 18 to 30 mo, 31 to 42 mo, 43 to 54 mo, 55 to 66 mo, and >66 mo. Regression equations including stage of lactation and 13 linear type traits in linear and quadratic forms accounted for 81 to 85% of variation of final score within herds and for 75 to 80% when herds were ignored.

Linear and quadratic coefficients for regression of final score on linear traits generally were greater than and less than zero, respectively, indicating diminishing increases and eventual decreases of final score with increases of scores for linear traits. Dairy character was most important in determining final score in all age groups. Other traits consistently important were teat placement, suspensory ligament, and fore udder. Rump angle, rump width, and udder depth were least important in determining final score.

FOOTNOTES

1 Supported by a grant from the American Jersey Cattle Club.






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Copyright © 1984 by the American Dairy Science Association ®.