Fertility monitoring in dairy herds

An important factor for the economy of dairy herds is their performance in reproduction. To achieve acceptable results, a fertility monitoring system is introduced in the present study. Using data of electronical dairy herd management programs, the system normally analyses one single control parameter. For this purpose, the fraction of repeat-breeding days of all production days was calculated. This variable merges both, the economically important parameter calving inter-Val and the cows getting more than one insemination without gestation and are slaughtered afterwards because of infertility. This variable was calculated for one dairy farm and analysed with control charts. So far, the use of control charts is very common in the industry, but the application of these charts in monitoring biological processes is rare. The great advantage of those charts is the classification of the process variation into unavoidable random variation and special variation because of preventable causes. In the present study, two different charts are introduced: the CUSUM and the EWMA chart. The borderline for random process variation is passed in both charts for the analysed farm. To find the reasons for this trespassing, the variables percent of repeat-breeder cows and time between inseminations were analysed. For the contemplated dairy herd both charts detected the increasing quota of repeat-breeder cows as reason for the growth of the fraction of repeat-breeding days of all production days. Overall, control charts and the variable fraction of repeat-breeding days of all production days seem to give a satisfactory overview about the herd performance. A monitoring system containing these two components could be a good tool for the herd manager and complete the appraisals of his electronical dairy herd management program.