Disease-related costs in confinement and grazing dairy cow systems.

Grazing is widely promoted for its potential welfare and environmental benefits, yet its economic implications for animal health remain unclear. Therefore, this study quantified annual disease-related costs in confinement and grazing systems on dairy farms using a deterministic bio-economic model, providing system-level disease cost estimates. Four diseases were included: ketosis, lameness, mastitis, and parasitic infections. A typical Dutch dairy farm was simulated over one year under full confinement and under grazing comprising six months pasture access and six months indoor housing. Total disease-related costs were estimated at €349 per cow per year under confinement and €317 under grazing, a difference of €32. In confinement, ketosis, lameness, mastitis, and parasitic infections accounted for €20, €113, €215, and €0 per cow per year, respectively, whereas the corresponding costs under grazing were €19, €93, €196, and €9 per cow per year. Sensitivity analyses of market prices, disease effect parameters, and system-based milk yield differences affected the magnitude, but not the direction of this finding. Across all sensitivity analyses, disease-related costs in the grazing systems were estimated to be lower than in the confinement system. Accounting for uncertainty in incidence rates did not alter the relative difference between systems, although confinement showed slightly greater cost dispersion. Disease-related costs represented approximately 11.1% and 10.1% of annual gross margins under confinement and grazing, respectively. Overall, the results indicate that, under the assumptions of the model, grazing can offer moderate economic advantages from an animal health perspective.