title: Comparison of cephalonium alone and in combination with an internal teat sealant for dry cow therapy in seasonally calving dairy cows.
abstract: OBJECTIVE
  To assess the effect of combining an internal teat sealant (ITS) and a long-acting cephalonium-based dry cow therapy (DCT) on the prevalence of cows with a somatic cell count (SCC) >150,000 cells/mL 60-80 days after calving, and the incidence of clinical mastitis diagnosed by farm staff in the first 100 days after calving.
  
  
  METHODS
  Cows from a spring-calving, pasture-based, dairy farm in the South Canterbury region of New Zealand were randomly allocated to receive cephalonium DCT (n=289) or cephalonium and internal teat sealant (n=304) at the end of lactation. Cows were inspected twice daily by farm staff during the dry period and following calving for signs of mastitis. Individual SCC were determined from herd tests conducted in the previous lactation and following calving. Logistic regression models were used to determine relationships with the prevalence of cows with a SCC >150,000 cells/mL after calving, and survival analysis was used to model time to the first case of clinical mastitis following calving at the cow and quarter level.
  
  
  RESULTS
  The OR for a cow with a SCC >150,000 cells/mL after calving, including age and individual SCC in the preceding lactation in the model, was 0.53 (95% CI=0.32-0.89) for cows treated with combination therapy compared to cows receiving cephalonium (p=0.017). At the cow level, including age and preceding SCC in the model, the hazard ratio for diagnosis of clinical mastitis by farm staff in the first 100 days of lactation was 0.60 (95% CI=0.39-0.98) for cows treated with combination therapy compared to cows receiving cephalonium (p=0.04). At the quarter level, the hazard ratio for diagnosis of clinical mastitis, with age included in the model, was 0.41 (95% CI=0.23-0.74) for the combination therapy compared to cephalonium alone (p<0.001).
  
  
  CONCLUSIONS
  The combination of internal teat sealant and cephalonium DCT was more effective than cephalonium alone at reducing clinical mastitis diagnosed by farm staff in the 100 days after calving, and the prevalence of cows with a SCC >150,000 cells/mL 60-80 days after calving.
  
  
  CONCLUSIONS
  This study adds to the evidence that the prevention of intra mammary infections throughout the dry period and up to calving by using combination therapy is important in reducing the incidence of farmer-diagnosed clinical mastitis and prevalence of cows with a SCC >150,000 cells/mL 60-80 days after calving.
authors.affiliation: a Centre for Dairy Excellence , 20 Wilson Street, Geraldine 7930 , New Zealand.
authors.forename: A J
authors.initials: AJ
authors.lastname: Bates
authors.affiliation: b Zoetis New Zealand Ltd , PO Box 2094, Shortland Street, Auckland 1140 , New Zealand.
authors.forename: G
authors.initials: G
authors.lastname: Chambers
authors.affiliation: c Institute of Veterinary, Animal and Biomedical Sciences, Massey University , Private Bag 11222, Palmerston North , New Zealand.
authors.forename: R A
authors.initials: RA
authors.lastname: Laven
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000008:administration & dosage / Q000627:therapeutic use*; D002417:Cattle; D002511:Cephalosporins / Q000008:administration & dosage / Q000627:therapeutic use*; D005260:Female; D007774:Lactation; D008321:Mammary Glands, Animal / Q000382:microbiology / Q000502:physiology; D008414:Mastitis, Bovine / Q000517:prevention & control*; D036801:Parturition; D049590:Postpartum Period; D011247:Pregnancy; D012621:Seasons
chemical_list: D000900:Anti-Bacterial Agents; D002511:Cephalosporins; C012813:cephalonium
keywords: Dry cow therapy; clinical mastitis; dry period; internal teat sealant