Relationships between Linearly Scored Components of Type and Final Score of Jersey Cows

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Abstract
Evaluations for final score and 13 components of type, scored linearly from 50-99 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 18-30 mo., 31-42 mo., 43-54 mo., 55-66 mo., and > 66 mo. Regression equations including stage of lactation and 13 linear type traits in linear and quadratic forms accounted for 81-85% of variation of final score within herds and for 75-80% 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. Maximum final score occurred at high scores (89-99 points) for stature, strength, dairy character, rump width, fore udder, rear udder height and width, and suspensory ligament; at slightly lower scores (79-89 points) for udder depth; and at intermediate scores (73-79 points) for foot angle, rear legs, rump angle, and teat placement. Regression equations predicting final score from linearly scored components of type may be used to define and monitor breed objectives in assigning final score.