ANALYSIS OF SURVIVORSHIP AFTER DISPLACED ABOMASUM IS DIAGNOSED IN DAIRY-COWS

The objective of this study was to analyze the survivorship of dairy c ows after displaced abomasum was diagnosed. Survivorship from the calv ing preceeding diagnosis of displaced abomasum to removal from the her d was investigated for cows that were diagnosed with displaced abomasu m compared with herdmates. For cows that were diagnosed with displaced abomasum, factors that affected survivor-ship from the diagnosis of t he disease to removal were investigated. Data from a total of 135 cows that had been diagnosed with displaced abomasum and 373 controls matc hed by herd and lactation number were available from a database at the University of Guelph. The hazard rate of removal from the herd was es timated using proportional hazard regression adjusted for intraherd co rrelation. Diagnosis of displaced abomasum significantly increased the hazarad rate of removal from the herd. For cows that were diagnosed w ith displaced abomasum the hazard rate of removal increased as parity increased. However, the hazard rate decreased with recurrent displaced abomasum and with higher days in milk at diagnosis of the disease. Al though the 305-d milk production of cows that were diagnosed with disp laced abomasum was lower during the lactation when the disease was dia gnosed, 305-d milk production was not associated with removal of cows with that disease from the herd. Milk production during subsequent lac tations did not differ between cows that were diagnosed with displaced abomasum and control cows. Low milk production during the subsequent lactations increased the hazard of removal of cows with that disease f rom the herd.