RELATIONSHIPS BETWEEN SIRE GENETIC EVALUATIONS FOR CONFORMATION AND FUNCTIONAL HERD LIFE OF DAUGHTERS

Linear and nonlinear relationships between functional herd life and conformation traits were investigated by regression of functional herd life of 63,602 Quebec Holstein cows on the estimated transmitting abilities of their sires for conformation traits. Relationships with functional herd life were obtained by inclusion in regression models of covariants for the deviations of cows in production of milk and fat. Individual conformation traits had low to moderate genetic relationships with functional herd life. Relationships were strongest for traits associated with udder conformation and feet and legs, and relationships were stronger for registered than for grade herds. Nonlinear relationships were present for some traits. Indexes to predict estimated transmitting ability of sires for functional herd life, based on combinations of estimated transmitting abilities of sires for conformation traits, explained .3 to .8% of phenotypic variation in functional herd life, which, for a heritability of functional herd life of .08, amounts to 15 to 40% of genetic variation in functional herd life. For registered herds, unlike grade herds, composite traits provided significant information on functional herd life and linear conformation traits. Correlations between indexes of conformation traits to predict estimated transmitting abilities of sires for functional herd life for registered versus grade herds were low to moderate. Selection for functional herd life based on conformation traits is possible but has moderate efficiency because of low to moderate relationships between conformation traits and functional herd life.