ach day of an extended calving interval results in severe economic loss for the farmers because of a decreasing milk production and increasing costs for separation rates [1]. A reduction of calving intervals by early pregnancy detection could be one approach to solve this problem. Thus an accurate pregnancy prediction improves the efficiency of herd management with respect to milk production. Today, the detection of bovine pregnancy is possible by transrectal palpation or ultrasonography 28 to 35 days after insemination. However, the correct application requires an experienced practitioner [[2], [3]] and normally several transrectal palpations. Wrong diagnosis because of aberrant uterine contents, and even early aborts by accidentally injuring the amniotic vesicle are potential risks [[4], [5], [6]]. Laboratory analytic methods for the identification of early pregnancy in cattle comprise the quantification of steroid hormone and glycoprotein concentrations in blood and milk samples. Currently these methods allow a reliable pregnancy diagnosis not before 28 to 30 days postfertilization. However, methods that allow a diagnosis around or before Day 20 after insemination are of considerable value. Such early pregnancy detection enables reinsemination in time of the consecutive estrus cycle.