Mastitis; a survey on the inter-dependence of the quarters of a cow.

This survey shows the dependence of the diagnosis "non-specific mastitis" on the method and interpretation of laboratory examination. Failures in bacteriological diagnosis will often lead to quarters being incorrectly diagnosed as being affected by "non-specific mastitis". The main aim of this survey was to study the interdependence of the quarters of cows with regard to laboratory results on mastitis. This survey shows that the criteria "high cell number" and "bacteriologically positive" in quarters have no random distribution. The number of cows with nil or four quarters positive is significantly higher than with a random distribution. Genetical difference in susceptibility could be the cause of the phenomenon. But this survey shows that non-genetical factors as age and difference between herds in level of mastitis are largely involved. It seems impossible in a field survey to estimate the genetical share in the high coincidence of the mastitis criteria within cows. In mathematical statistical analysis of the results in quarter-samples, with the aim to compare two groups of cows, the number of elements to compare is the number of cows and not the number of quarters. Because of the coincidence of mastitis symptoms in individual cows, the possibility for statistical evaluation of quarter results is restricted.