A STOCHASTIC-MODEL FOR SIMULATION OF THE ECONOMIC CONSEQUENCES OF BOVINE VIRUS DIARRHEA VIRUS-INFECTION IN A DAIRY-HERD

A dynamic, stochastic model simulating the technical and economic cons equences of bovine virus diarrhoea virus (BVDV) infections for a dairy cattle herd for use on a personal computer was developed. The product ion and state changes of the herd were simulated by state changes of t he individual cows and heifers. All discrete events at the cow level w ere triggered stochastically. Each cow and heifer was characterized by state variables such as stage of lactation, parity, oestrous status, decision for culling, milk production potential, and immune status for BVDV. The model was controlled by 170 decision variables describing b iologic and management variables including 21 decision variables descr ibing the effect of BVDV infection on the production of the individual animal. Two markedly different scenarios were simulated to demonstrat e the behaviour of the developed model and the potentials of the appli ed modelling principle. The validation problem in relation to the mode l was discussed. A comparison between real and simulated data using da ta from a published case report was shown to illustrate how user accep tance can be obtained.