[Economic aspects of diseases and dairy herd health programs in the Netherlands with special reference to mastitis (author's transl)].

Animal diseases cause considerable losses among dairy cattle in the Netherlands. Model calculations show that the loss on farm level from animal diseases is approximately Dfl 440.--per cow per annum. Increasing attention is being paid to one of them e.g. mastitis. This disease causing an annual loss on farm level of approximately Dfl 125.--per average cow present (a.c.p.). Currently, a Mastitis Control Program (MCP) is being advocated. When the expected profits and cost of the MCP are analysed, different economic levels can be distinguished. Analysis on farm level showed that, when the MCP is carried out, the average calculated losses can be reduced by half, so that, with the exception of the first years, an increase in income of Dfl. 30.--per a.c.p. is anticipated. When less than 12.5 percent of the quarters are infected and less than 2 or 3 per cent of the quarters show clinical mastitis in a period of twelve months, the expected profits of the MCP are less than the cost. When all the farmers (the "sector") reduce the incidence of mastitis, the expected increase in income will be smaller because of price-effects. From the national point of view, the profitability of the MCP will primarily depend on the national-economic net price of the additional milk production, which should be higher than Dfl. 30.--per 100 kg. to make it pay. Finally, it was evident that production of the same quantity of milk by fewer animals, resulting from a reduction of the incidence of mastitis, is profitable on a national level, because of a decrease in the import of concentrates.