Experimental Linear Descriptive Type Classification

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Abstract
It was determined if linear descriptive scores ignored age and stage of lactation. Holstein cows in 5 herds were classified by 2 evaluators of the Holstein Association. Each herd was scored by a single classifier on experimental linear system. Body measurements logically related to trait descriptions were taken approximately 1 mo. later. Body measurements and linear scores were analyzed for age, stage and interaction effects. Also, linear scores (322) were predicted from related body measurements, and residuals (actual score minus predicted score) were analyzed to determine if classifiers were adjusting subjectively for effects of age and stage of lactation. Classifier and herd within classifier differed for most traits. Age and interactions of age with classifier, indicators of differential age adjustment by evaluators, were significant sources of variation only for residuals of body strength, rear udder width, rump width and teat placement. The absence of age and stage effects from the residual analyses provides evidence that linear scores for most traits ignored these factors. Residuals also regressed about 0.2 on final score of the cow. Cows with high final scores were assigned linear scores that were relatively higher han their body measurements would justify.

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