MULTIPLE-TRAIT PREDICTION OF TRANSMITTING ABILITIES FOR HERD LIFE ANDESTIMATION OF ECONOMIC WEIGHTS USING RELATIVE NET INCOME ADJUSTED FOROPPORTUNITY COST

Genetic and phenotypic (co)variances among linear type traits, final s core, first lactation milk and fat yield, and 84-mo totals for longevi ty, relative net income, and relative net income adjusted for opportun ity cost of postponed replacement were estimated with a multiple-trait sire model. Data were from 433,116 cows in herds participating in the classification program for conformation traits of the Holstein Associ ation of America. Yield information from all cows in classified herds indicated that classified cows are not a random sample. Heritability o f net income adjusted for opportunity cost was higher, .17, than unadj usted net income, .12, but the genetic correlation between the estimat es of net income was high, .97. Adjusted net income also had high gene tic correlations with first lactation milk yield, .80; fat yield, .60; and dairy form, .48. Heritability of longevity (months in milk to 84 mo) was .06. Adjustment of net income for opportunity cost lowered the genetic correlation with longevity from .84 to .70. Evaluation of lif etime merit using traits measured during first lactation with economic weights developed using adjusted net income was more accurate than in direct prediction of longevity; the approximate reliability of a first -crop AI sire for lifetime merit was .65 compared with .42 for longevi ty.