Abstract

Facial eczema (FE) is a metabolic disease resulting primarily from damage to the liver and bile ducts. It is caused in ruminants by the effects of a mycotoxin, sporidesmin, produced by the fungus Pithomyces chartarum. The disease causes significant loss in agricultural production mainly in northern New Zealand. Sporidesmin toxin is produced in a laboratory and made available to those sheep breeders who wish to increase the level of FE tolerance in their flocks. The sheep industry in NZ has made steady progress towards increasing genetic tolerance to FE by testing potential future sires in ram-breeding flocks with an artificial challenge of sporidesmin. Ramguard provides the sporidesmin to breeders to dose their sheep at a specified dose-rate which is dependent on the level of tolerance already obtained. The Ramguard service has operated from August 1988 and has 60 clients dosing a total of 800 to 1100 rams each year. Most of the long-term-testing flocks are now using a dose rate six times higher than at the outset, which indicates animals in these flocks are tolerant to all but the severest outbreaks of FE. The heritability estimate for resistance to facial eczema is high at 0.45 ± 0.03.

NC, Amyes, and AD Hawkes

Proceedings of the New Zealand Society of Animal Production, Volume 74, Napier, 154-157, 2014
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