A stochastic model for the derivation of economic values and their standard deviations for production and functional traits in dairy cattle

The objective of this paper was to present a model of a dairy cattle production system for the derivation of economic values and their standard deviations for both production and functional traits under Danish production circumstances. The stochastic model used is dynamic, and simulates production and health in a dairy herd. Because of indirect effects between traits, the phenotypic levels of (related) traits can change as a result of genetic changes. Economic values for milk production and body weight were 0.28 and -0.76 euro/kg per cow-year respectively. For incidence of milk fever, mastitis, retained placenta and laminitis economic values were -402.1, -162.5, -79.0 and -210.2 euro/incidence per cow-year. The economic values for involuntary culling rate, stillbirth and conception rate were -6.66, -1.63, and 1.98 euro/% per cow-year, respectively and the economic value for days from calving to first heat was -0.94 euro/day per cow-year. Standard deviations of economic values expressing variation in realised profit of a farm before and after a genetic change were computed using a linear Taylor series expansion. Expressed as coefficient of variation, standard deviations of economic values based on 1000 replicates ranged between 0.07 (milk production) to 16 (retained placenta).