Ultrasonographic assessment of body condition in dairy herd management.: Part 1:: Backfat thickness and milk yield

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 the 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 to the end of the first third of the lactation period. At the same time, milk protein content 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 highest body fat losses occur and when energy balance returns to positive values.