Tel.+49 30 838 62261 Fax.+49 30 838 62512
The main target of the study was to identify reference values for the ultrasonographic backfat measurement to be used in dairy herd management. For this purpose, body condition was evaluated from 46111 dairy cows on 78 different farms. In this essay milk yield has been related to the development of body condition in course of lactation. Increasing milk yield leads to enhanced losses of body fat reserves in early lactation and the return to a positive energy balance is slipping into later lactation. At the same time, milk protein content is declining according to the higher energy deficit. By evaluating body condition twice in intervals of four weeks more detailed information is available concerning the time when biggest body fat losses occur and when energy balance returns to positive values.