May 12, 2009

Facial Eczema (FE). Farmer Information. Part 18. (Sheep). Mangement. Minimising losses after outbreaks.

 Agriculture, animal husbandry, animal health, disease, Facial Eczema, Sheep, management, minimising losses after outbreak.

By Dr Clive Dalton

Original 1991 information written by Dr Barry Smith and Dr Neale Towers, Ruakura Agricultural Research Station, Hamilton, New Zealand.
18. Facial Eczema: (Sheep).  Mangement. Minimising losses after outbreaks.

  • If an FE outbreak occurs in your flock there are strategies that can be followed to minimise animal and financial losses. 
  •  Don't panic and immediately ship lambs or ewes to the works. You will incur freight and killing charges and clinical animals with jaundice will be condemned.
  • At the first sign of clinical FE consider these points:
  • Check weather conditions. Do they favour further spore production? If so start protection procedures if not already in place.
  • Check control procedures are being correctly followed. Recalculate zinc dose and fungicide application rates. Have someone else independently cross-check.
  • Remember that neither zinc dosing nor fungicide spraying will give complete protection especially against very high spore counts.
Best options
  • The best options will depend on the severity of the FE outbreak, the feed supplies available and the class of stock involved. 
  •  Remember that - The severity of the external signs and the severity of the liver damage are not closely related.
  • Some animals with FE damaged livers will become jaundiced as bile leaks back into the bloodstream after major bile ducts become blocked.
  • Jaundiced animals will become extremely sensitive to exposure to light (i.e.  photosensitive).
  • It only takes a few minutes exposure to bright sunlight to cause extreme stress to photosensitive animals.
  • Many of the deaths from FE are due to the stress of photosensitisation, therefore it is imperative that affected animals are given access to heavy shade.
  • Jaundiced animals will be condemned at the works.
  • The liver can regenerate and repair if the original damage is not too severe and the jaundice will clear. To recover affected animals need time, shade and good food. If they don't recover they would have been condemned at the works.
Overall farm situation
  • With these facts in mind consider the overall farm situation.
  •  What is the feed situation? Can you afford to treat the affected mob well for a few weeks or do you need to quit stock to lower grazing pressure (and therefore the FE risk) on the other stock?
  • Can you protect the flock from further FE outbreaks?
  • Draft out all affected animals and examine for the most severe signs of jaundice by looking for yellowing of eyes, mouth, gums, vulva etc.
  • Separate clinically affected animals into mobs with or without severe jaundice.
Works Lambs
  • If no clinical signs.  Send to works now or later depending on body condition, feed availability and your ability to prevent further outbreaks.
  •  Clinical cases with minor jaundice. Send to works.
  • Clinical cases with severe jaundice. Keep until jaundice clears and body condition improved and then cull or send toworks.
Ewes and Ewe Lambs
  • If no Clinical signs, protect from further outbreaks.
  •  Give best possible feed.
  • Give shade if possible.
  • Assess condition over next few months and cull unthrifty animals.
Affected animals (with or without jaundice)
  • Keep in covered yards, woolshed or heavily treed area with access to water, hay and/or silage.
  •  Allow access to safe grazing at night (spray with fungicides).
  •  Prevent and/or treat flystrike and infections.
  • Cull animals not improving when jaundice clears.
  • Record numbers of affected ewes and do not keep replacements from them if number allow.
  • Do not quit ewes surviving an FE outbreak. Resistance to FE is heritable so those ewes surviving are a valuable resource. 
  • Buy rams from a breeder selecting for FE resistance and take advantage of the disaster to begin breeding a more resistant flock.
  • If no clinical signs, treat as for ewes and ewe lambs.
  •  With affected animals, cull immediately as susceptibility to FE is highly heritable.

This material is provided in good faith for information purposes only, and the author does not accept any liability to any person for actions taken as a result of the information or advice (or the use of such information or advice) provided in these pages.

No comments:

Post a Comment