Studies on genetic evaluation of udder health using the LactoCorder

Starting in October 1998, a new milkmeter (LactoCorder) for dairy recording was introduced in Bavaria, Germany. With the LactoCorder milk yield is rec orded but information is also available on the milk flow. In addition the n umber of somatic cells in the milk was analysed. About 1 mio records of cow s (German Simmental. German Brown, German Holstein Frisian) with up to 3 la ctations were available to analyse the relationship between traits derived from the milk flow curve and somatic cell score. In analyses applying fixed models effects of herd test day, lactation, days in milk, age at calving, time of milking and bimodality of the flow curve were found to be highly si gnificant for most of the traits. Correlation between average flow rate (DMHG) to maximum flow rate (HMF) was high (r = 0.84) indicating that selection on average flow rate has provoke d an increase of maximum flow rate. Correletations between traits derived from the milk flow curve and cell sco re are low. The highest value was found with the duration of maximum flow r ate (tP1). Animals showing a long plateau had lower cells scores, while a h igh flow rate and a long duration of decreasing flow rate (tAb) was related with higher cell numbers. A research project was initiated to implement a genetic evaluation for milkability, making use of the detailed information now available on milk flow curves.