Adjustment of Linear Type Scores from Holstein Classification for Age and Stage of Lactation

¹ Department of Animal Science, University of Minnesota, St. Paul 55108
² Department of Animal Science, University of Minnesota, St. Paul 551086
³ Holstein Association, Brattleboro, VT 05301

Type scores from classification were obtained from the Holstein Association to compare methods of adjustment for age and stage of lactation at time of classification. Scores were for final score and 14 linear type traits and were analyzed separately for parity groups. Analysis was with ordinary least squares, and both age and stage of lactation were significant for most traits within parity groups. Multiplicative adjustment factors were calculated after addition or subtraction of least squares estimates to or from constants. Several methods of adjustment were compared by assessing uniformity of means and standard deviations for adjusted classes. The method that gave adjusted scores with least range of standard deviations for classes was deemed superior. Optimal method of adjustment differed for traits.

Key Words: type • adjustment factors • Holstein

Submitted on May 9, 1990
Accepted on July 9, 1990