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Press release - Thursday, January 29, 2015

Examining animal disease treatment per farm or per illness is economically better than per sector.

ILVO-Ghent University doctoral thesis of Mariska van der Voort: ‘Using production economics for relating animal diseases with farm performances’
Decisions about animal disease management (prevention, control, treatment) are best done by examining key indicators of the individual farm and not the averages of the entire sector. The profit or loss booked by paying (more or less) attention to a disease appears to differ greatly from farm to farm. That was the conclusion of Mariska van der Voort in her doctoral thesis: “According to my calculations advice on how best to manage disease must be farm-specific in order to produce the most profitable result.”
Van der Voort focused on the case of intestinal parasites in dairy farming. Especially for this sector, new calculations can be made regarding the priorities on individual farms about disease management. Economic and medical considerations can now be mapped with much more precision.

Intestinal parasitic infections

Nearly all grazing cattle on pasture are infected with intestinal parasites. Such an infection leads to reduced performance, such as lower milk production, feed intake and feed conversion. Although the impact of intestinal parasites is not always directly visible to the farmer, they are still important.

Mariska van der Voort discovered marked differences in the financial end result of a specific management strategy, even when the severity of infection was the same among the farms. She revealed a link between the way the dairy farmer used inputs (pasture, roughage and concentrates), the infection pressure, and the resulting performance scores.

The infection pressure in adult cattle is growing due to increase resistance to antihelmintics. Dairy farmers must therefore make the right decisions, in part to avoid unnecessary treatment.

To help farmers make these decisions, van der Voort suggests a method that uses “production economic theory”. This methodology combines the most recent methods from veterinary and agricultural economic research into one analysis method. This is used to examine the economic impact of intestinal parasites and control strategies on the level of the individual farm.

The first step is to discover the negative effect of the infection on the efficiency of the farm. Farm efficiency is defined as the degree to which an amount of inputs leads to maximal milk production. The effect of infection on farm efficiency appears to be relatively more important on highly efficient farms than on middle- to low efficient farms. This suggests that farms with a lower efficiency will do better to focus first on other improvements than lowering the infection pressure.


To reduce the use of antihelmintics in the dairy industry, several alternatives for pasturing can be used to reduce infection pressure. Examples are shortening the grass seasons and shorter pasturing periods per day. These alternative strategies only reduce the average economic results, however, as shown by this doctoral study. Because the real economic effect differs greatly from farm to farm, this study encourages a case-by-case approach.


ILVO Communication: Greet Riebbels, +32 486 26 00 14, 
Researcher: Mariska van der Voort, +32 272 23 74,

Promotors: Prof. Dr. ir. Guido Van Huylenbroeck, Prof. Dr. ir. Ludwig Lauwers, Dr. Johannes Charlier