[Productive life-span of dairy cows and its economic significance. I. Disposal of dairy cows: the current situation (author's transl)].

The current situation regarding the replacement of dairy cows is discussed. Attention is successively paid to the duration of herd life and the replacement rate, the reasons for disposal and the relationship between age and the probability of disposal. Little research including all the required elements at the same time has been done in this field. Therefore, the literature can offer only a rough idea of the current situation regarding the replacement of dairy cows (Tables 1 and 2). Further research along a few lines presented in this paper is advocated. However, the findings derived from the literature may be used in an economic model to quantify the economic significance of differences in the herd life of dairy cows. This subject will be elaborated in two subsequent papers.