Conformation Resulting from Selection for Milk Yield of Holsteins1,2

Abstract

Conformation from official Holstein classification program of daughters sired by bulls with high estimates of Predicted Difference milk was compared with conformation of daughters sired by bulls near breed average for milk in 1964 to investigate correlated response to selection for milk yield. In 1964, foundation cows were paired by sire and randomly assigned to two genetic groups, selection and control, for one experimental herd. Selection group was mated to four sires highest for Predicted Difference milk each year. Control group was mated to 20 bulls near breed average for milk in 1964. Conformation was recorded for final score, four scorecard categories, and 11 descriptive traits by Holstein Association classifiers. Data from 320 cows were collected from 1968 to 1982. When a lower boundary of 60 points was placed on final score with a range from 50 to 100, the selection group exceeded controls for final score from first classification. Compared with controls, selection cows rated higher for dairy character and body capacity. For descriptive traits, selection cows excelled controls for stature, front ends, and rear udders. Controls did not have a significant advantage for any trait.