A zinc-containing intraruminal device for prevention of the sporidesmin-induced cholangiopathy of facial eczema in calves.
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.
Munday
R
R
AgResearch, Ruakura Research Centre, Private Bag 3123, Hamilton, New Zealand. rex.munday@agresearch.co.nz
Thompson
A M
AM
Smith
B L
BL
Towers
N R
NR
O'Donnell
K
K
McDonald
R M
RM
Stirnemann
M
M