[Difference in susceptibility to mastitis between the Dutch-Friesian and Meuse-Rhine-Yssel breeds of cattle (author's transl)].

A randomized study in the Netherlands showed that symptoms of mastitis were more common in animals of the Meuse-Rhine-Yssel breed than they were in those of the Dutch-Friesian breed. The samples were taken at random from large groups of animals (approximately 10,000) of the dairy cattle population in the Netherlands, quarter samples being examined for the presence of the causative organisms of mastitis and cell counts being made. Differences between the two breeds were also observed in herds on the experimental farm "'t Gen" on which the animals were reared and kept in the same environment. Therefore, there is some justification in defining these differences as genetic. The results of the studies suggest that a group of animals showing lower cell counts during the first lactation will be less susceptible to mastitis. Studies in a cow-house of the Central Veterinary Institute revealed a significant difference in increase of the cell count between animals of the Dutch-Friesian breed and those of the Meuse-Rhine-Yssel breed following intramammary injection of a staphylococcal beta toxin. Further analysis of the results of the randomized study showed that differences in susceptibility to mastitis do not become plainly apparent until later in life. In view of the results of these studies, it would seem advisable to pay more attention to differences in susceptibility to mastitis in stock-breeding.