Effect of Herd and Sire on Uniform Functional Type Trait Appraisal Scores for Ayrshires, Guernseys, Jerseys, and Milking Shorthorns

Type appraisal data supplied by United States breed organizations for Ayrshires, Guernseys, Jerseys, and Milking Shorthorns were examined for genetic and environmental sources of variation. Repeatabilities were highest for pelvic angle, udder depth, stature, suspensory ligament, and final score (.51 to .74) and lowest for foot shape (.15 to .29). Variances and covariances were estimated from appraisals from 230 Ayrshire, 352 Guernsey, 699 Jersey, and 51 Milking Shorthorn herds and represented 117, 157, 333, and 32 sires. Herd variances by trait and breed ranged from 2 to 23%. Herd effects were large for stature and rear udder width of Ayrshires, for most traits of Jerseys, and for udder depth of Milking Shorthorns. Herd X sire variance was small but averaged 3% across all breeds and traits. Heritabilities ranged from .06 to .75. Stature had the highest heritability (.34 to .75) for all four breeds. Heritabilities also were high for chest and body (.42), rump width (.36), and pelvic angle (.34) for Guernseys; pelvic angle (.29) and udder depth (.27) for Jerseys; and chest and body (.70), rump width (.50), and final score (.44) for Milking Shorthorns. Foot shape had the lowest heritability for Ayrshires, Guernseys, and Jerseys (.06 to .07). Most of the phenotypic correlations between appraisal traits were low to moderately high. Genetic correlations were calculated.