title: A zinc-containing intraruminal device for prevention of the sporidesmin-induced cholangiopathy of facial eczema in calves.
abstract: OBJECTIVE
  To develop and evaluate a zinc-containing intraruminal controlled-release bolus for protection of calves (175-250 kg bodyweight) against facial eczema (FE).
  
  
  METHODS
  Boluses releasing zinc, in the form of zinc oxide, at rates ranging from 1.67 to 4.25 g/day were administered to calves which were challenged 4 weeks later with the FE toxin, sporidesmin. The efficacy of the boluses in protecting against sporidesmin-induced cholangiopathy was determined by measuring serum activities of gamma-glutamyltransferase (GGT).
  
  
  RESULTS
  A bolus releasing zinc at approximately 4.25 g/day gave excellent protection against sporidesmin toxicity for periods of up to 5 weeks duration.
  
  
  CONCLUSIONS
  This zinc-containing intraruminal controlled-release bolus has the potential to markedly reduce the incidence and severity of FE in calves within a 175-250 kg bodyweight range.
authors: AgResearch, Ruakura Research Centre, Private Bag 3123, Hamilton, New Zealand. rex.munday@agresearch.co.nz
authors: R
authors: R
authors: Munday
authors: A M
authors: AM
authors: Thompson
authors: B L
authors: BL
authors: Smith
authors: N R
authors: NR
authors: Towers
authors: K
authors: K
authors: O'Donnell
authors: R M
authors: RM
authors: McDonald
authors: M
authors: M
authors: Stirnemann