title: Association of herd BRSV and BHV-1 seroprevalence with respiratory disease and reproductive performance in adult dairy cattle.
abstract: BACKGROUND
  The aim of this study was to detect the associations between bovine herpesvirus 1 (BHV-1) status of a herd and respiratory disease (BRD) occurrence and reproductive performance in pregnant heifers and cows. The association between management-related factors and higher BRD occurrence was also estimated.
  
  
  METHODS
  Serum samples, collected from cows and youngstock from 103 dairy cattle herds, were analyzed for antibodies against BHV-1, bovine respiratory syncytial virus (BRSV), bovine viral diarrhoea virus (BVDV), and Mycoplasma bovis. A questionnaire was used to collect data concerning herd management factors and reproductive performance, as well as the occurrence of clinical signs of respiratory disease in the last two years, as evaluated by the veterinarian or farm manager. Multiple correspondence analysis (MCA) and logistic regression analysis were performed to identify and quantify the risk factors.
  
  
  RESULTS
  A low to moderate prevalence (1-49%) of BRSV antibodies among youngstock was associated with a high occurrence of respiratory disease (OR = 6.2, p = 0.010) in cows and in-calf heifers. Employees of the farm may participate in the spread of such disease. Larger herd size, loose-housing of cows, housing youngstock separately from cows until pregnancy, and purchasing new animals were factors possibly related to a high occurrence of respiratory disease symptoms in pregnant heifers and cows. The highest risk of abortions (> 1.3%) and increased insemination index (number of inseminations per pregnancy) (> 1.9) occurred in herds with a moderate prevalence of BHV-1 antibodies (1-49%) in cows.
  
  
  CONCLUSIONS
  BHV-1 was not associated with acute respiratory disease in adult dairy cattle, however was significantly related to reproductive performance. BRSV possesses the main role in respiratory disease complex in adult dairy cattle.
authors.affiliation: Institute of Veterinary Medicine and Animal Sciences, Estonian University of Life Sciences, Kreutzwaldi 62, Tartu, Estonia. Kerli.Raaperi@emu.ee
authors.forename: Kerli
authors.initials: K
authors.lastname: Raaperi
authors.forename: Stephanie
authors.initials: S
authors.lastname: Bougeard
authors.forename: Annely
authors.initials: A
authors.lastname: Aleksejev
authors.forename: Toomas
authors.initials: T
authors.lastname: Orro
authors.forename: Arvo
authors.initials: A
authors.lastname: Viltrop
mesh_terms: D000034:Abortion, Veterinary; D000367:Age Factors; D000822:Animal Husbandry; D000818:Animals; D000914:Antibodies, Viral / Q000097:blood; D048090:Bovine Respiratory Disease Complex / Q000175:diagnosis / Q000453:epidemiology* / Q000821:virology; D002417:Cattle; D004797:Enzyme-Linked Immunosorbent Assay / Q000662:veterinary; D004957:Estonia; D005260:Female; D006566:Herpesviridae Infections / Q000175:diagnosis / Q000453:epidemiology / Q000662:veterinary* / Q000821:virology; D007242:Herpesvirus 1, Bovine / Q000302:isolation & purification* / Q000502:physiology; D007314:Insemination; D016015:Logistic Models; D008954:Models, Biological; D011247:Pregnancy; D012098:Reproduction; D012307:Risk Factors; D012680:Sensitivity and Specificity; D016036:Seroepidemiologic Studies
chemical_list: D000914:Antibodies, Viral