Incidence of displaced abomasum (DA) in dairy cows is at least 10 times higher in Wisconsin herds than in Sweden, even though average fat-corrected milk production levels are similar. In southern Wisconsin an incidence of 2.5-3.5% appears normal (Dr. Rhoda, personal communication, Evansville, WI). Feed ingredient and breed differences may be associated with different incidence rates between countries. However, a preliminary investigation (Pehrson, unpublished) indicated that Wisconsin feeding and management practices during the peripartal period may be closely associated with the high incidence rate. The primary objective of the present study was to further evaluate this hypothesis (Trial B). A secondary objective was to collect clinical data with regard to occurrence of DA in the same geographic area (Trial A).