Potential use of parameters of the milk flow curve for genetic evaluation of milkability

Abstract

Starting in October 1998, a new milkmeter (LactoCorder) for dairy recording was introduced in Bavaria, Germany. With the LactoCorder milk yield is recorded but information is also available on milk flow. Based on thresholds of the flow rate, parameters are defined, e.g., maximum flow rate and duration of maximum flow rate. The LactoCorder is used on farms participating in test plans with alternate milk recording and sampling (AT), and on farms with milk recorded twice a day and alternate sampling (ATM), respectively, resulting in approximately 65% of the recorded cows having results obtained with the LactoCorder. A research project was initiated to implement a genetic evaluation for milkability, making use of the detailed information now available on milk flow curves. Since genetic relationships between udder health and milkability are well known, ongoing research is also focusing on this topic. For these analyses, information on somatic cell count will be added. Parameters of the milk flow curve included in a genetic evaluation will have to be selected with regard to milkability as well as to udder health. In analyses fixed 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 significant for most of the traits.