title: Risk factors associated with hemorrhagic bowel syndrome in dairy cattle.
abstract: OBJECTIVE
  To determine risk factors associated with hemorrhagic bowel syndrome (HBS) among dairy cattle in the United States and identify characteristics of HBS in individual cows.
  
  
  METHODS
  Cross-sectional, population-based survey.
  
  
  METHODS
  A stratified random sample of 1,013 dairy operations with > or = 30 cows located in 21 states.
  
  
  METHODS
  Information on management and animal health-related topics was collected with a questionnaire.
  
  
  RESULTS
  HBS was estimated to have been observed on 9.1% of operations during the preceding 5 years and on 5.1% of operations during the preceding 12 months. Factors found in multivariable analysis to be associated with the occurrence of HBS during the preceding 12 months were large herd size, administration of bovine somatotropin, and routine use of milk urea nitrogen concentration to determine ration composition. Use of pasture as part of the lactating cow ration during the growing season was associated with decreased odds of HBS in operations with rolling herd average milk production < or = 20,000 lb, whereas in operations with higher milk production, use of pasture was not associated with occurrence of HBS. For individual cows with signs consistent with HBS, the third lactation was the median of the parity distribution and the median time between parturition and the onset of clinical signs was 104 days.
  
  
  CONCLUSIONS
  Results suggest that management practices implemented to achieve high milk production may increase the risk of developing HBS in dairy cattle. Increased consumption of a high-energy diet seems to be the most plausible common pathway for all of the risk factors that have been described.
authors.affiliation: Department of Population Health and Reproduction, School of Veterinary Medicine, University of California, Davis, CA 95616, USA.
authors.forename: Roy D
authors.initials: RD
authors.lastname: Berghaus
authors.forename: Brian J
authors.initials: BJ
authors.lastname: McCluskey
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Callan
mesh_terms: D000821:Animal Feed / Q000009:adverse effects; D000822:Animal Husbandry / Q000379:methods; D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D002417:Cattle; D002418:Cattle Diseases / Q000453:epidemiology* / Q000209:etiology; D003430:Cross-Sectional Studies; D003612:Dairying / Q000379:methods*; D005260:Female; D006471:Gastrointestinal Hemorrhage / Q000453:epidemiology / Q000209:etiology / Q000662:veterinary*; D007774:Lactation; D008892:Milk / Q000378:metabolism; D006109:Poaceae; D012307:Risk Factors; D013577:Syndrome; D014481:United States / Q000453:epidemiology