[Economic losses to farms due to paratuberculosis in cattle].

The results of a study on economic losses to farms caused by paratuberculosis in dairy cattle are reported. Quantification of the decrease in production and determination of standard losses due to premature disposal using calculations based on a model were stressed. A decrease in production of 19.5 per cent compared with the last lactation but two was recorded in animals showing clinical symptoms of paratuberculosis. The decrease in production was 5 per cent during the last lactation but one compared with the previous lactation. The decrease in production during lactation on disposal was 16 per cent and 6 per cent during the last lactation but one compared with the last lactation but two in animals with non-clinical forms of paratuberculosis. The average cow showing clinical symptoms of paratuberculosis, which was disposed of, caused a total loss of 2,250 guilders, whereas the average cow with a non-clinical form of Johne's disease was estimated to cause a loss of 1,800 guilders.