aCenter for Animal Disease Modeling and Surveillance (CADMS), School of Veterinary Medicine, University of California, Davis, CA, USA bDanish Cattle Federation, DK-8000 Aarhus C, Denmark cInternational EpiLab and Department of Epidemiology and Risk Assessment, Danish Food and Veterinary Research, DK-2860 Soeborg, Denmark dDepartment of Veterinary Diagnostics and Research, Danish Food and Veterinary Research, DK-1790 Copenhagen V, Denmark eDepartment of Large Animal Sciences, Section for Veterinary Epidemiology, The Royal Veterinary and Agricultural University, DK-1870 Frederiksberg C, Denmark
Abortion in dairy cows in well-managed dairies is not common but differences have been reported probably due to variation in animal health, nutrition and management, as well as difficulties in observing the aborted material. A 38-month study of 507 large Danish dairy herds revealed 3354 late-term abortions and 224,419 calvings were recorded. During the study period, a total of 3717 submissions were made to the Danish Institute for Food and Veterinary Research (DFVF). A broad spectrum of abortive agents was isolated but none were found to be statistically associated with abortions. The number of abortions in a month on a dairy was significantly (P < 0.001) associated with the number of cows in the third trimester but explained only 11% (R2adj = 0.114 of the variability of the reported abortions. A total of 23 herds (4.5%) reported 531 abortions (15.8%). Although a marginally significant (P = 0.11) risk of increased abortions was found to exist in bovine viral diarrhea virus- (BVDV) infected herds, it could be at least partially explained by additional calvings in those herds. Temporal correlation between inseminations and abortions was statistically significant (P < 0.001) with the highest correlation (r = 0.47–0.51) after lagging abortions on insemination by 6–8 months. No indication of spatial clustering was detected for either specific-abortogenic pathogens or high aborting dairies using either Cuzick–Edwards’ (P > 0.17) or spatial scan tests (P > 0.23). Ederer–Myers–Mantel test was applied to 3 years of data on the highest aborting dairies and showed that July had nearly double the expected number of maximum monthly abortions (P < 0.001). These findings provide further insight into the reported abortion pattern in Danish dairies and may facilitate planning future control programs.
This article was published in Preventive Veterinary Medicine, 77, Tim E. Carpentera, Mariann Chrièlb, Mette M. Andersenc, Liana Wulfsond, Astrid M. Jensene, Hans Houee and Matthias Greinerc, An epidemiologic study of late-term abortions in dairy cattle in Denmark, July 2000–August 2003, 215-229, Copyright Elsevier 2006.