Relationships Between Linear Descriptive Type Traits and Body Measurements

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Abstract
Holstein cows (297) in 5 Virginia Institutional Breeding Project ([USA] herds were evaluated subjectively by a linear scoring system and were measured objectively for related physical components of conformation. Repeatabilities for physical traits ranged from 45% (rear leg angle) to 90% (stature) with most traits exceeding 70%. Subjectively scored linear traits were generally skewed negatively with few cows scored in the lower 40% of scores for rump, side view (slope), rear legs, side view (set), strength of body and dairy character. Multiple squared correlations for models predicting linear scores of individual cows from their related physical traits ranged from 0.09-0.68 with a majority between 0.30 and 0.50. Correlations for identical models, of means of linear scores and physical traits, ranged from 0.45-0.97, with most exceeding 0.70. Relationships between linear scores and physical traits were as expected and, in general, were homogeneous between classifiers. Changes in physical traits per point change in linear scores were small. The linear type evaluation system examined distinguished with reasonable accuracy among cows the differences in their physical components of conformation. Improvements in the system may be possible by redescribing point ranges for certain traits and by providing benchmarks to aid in subjective evaluation.