A Stochastic Model Simulating Paratuberculosis in a Dairy Herd

摘要

The PTB-Simherd is a dynamic, stochastic, and mechanistic Monte-Carlo model simulating a dairy herd including young stock. Paratuberculosis and relevant control strategies against this disease was built into an existing simulation model. The model isable to simulate both epidemiological, technical and economic consequences of paratuberculosis and control strategies against it in the herd. It also reflects indirect effects of paratuberculosis and control strategies through effect on replacement and herd demographics. A cow is specified with biological parameters (updated in weekly time-steps), including paratuberculosis stated by infection status and latest results of two different diagnostic tests. Management is specified at herd level with 353 parameters of which 78 are related to paratuberculosis. Risk of infection is specified for five separate periods. Infected animals are given three risks of disease progression to next state of paratuberculosis: A weekly base risk, risk from calving and feeding stress. Production effects of paratuberculosis are specified (depending on infection state) by reduced milk production, body weight loss, reduced fertility, and an increased death risk. Two groups of control strategies can be combined or used separat