New Zealand Sheep - Facial Eczema damaged liver

By Dr Clive Dalton

The fungus Pithoymyces chartarum is found in pastures mainly in the Northern parts of New Zealand, and in autumn after a summer dry period when a lot of dead litter has accumulated in the pasture base, rain and dew can provide ideal conditions for the fungus to produce spores in large numbers. But the spores can also be found in large numbers on new short fresh autumn grass.

The fungal spores, especially the freshly-grown ones produce a toxin called sporidesmin, which causes thickening of the bile duct and may even cause its complete blockage.

Sheep gall bladder punctured to show bile and healthy
bile duct entering the liver tissue

A damaged liver cannot get rid of waste products, and a breakdown product of chlorophyll accumulates in the tissues causing jaundice and sensitivity to sunlight.

Sunlight very quickly causes swelling and severe inflammation on exposed white skin parts of the body.

There can be some repair of the liver, but it depends very much on the level of damage. In a recovered liver you will see knew small lobes that have grown.

Sheep's liver cut through centre

The liver pictured above is from a 6-year-old ¾ Romney ewe with ¼ Finn. She spent 5 years of her life on a farm that is very prone to FE, so there’s little doubt that she will have experienced a toxin challenge and liver damage during those years. She has reared twins most years in her life and it’s amazing that she was able to do this.

In the picture at the knife point is a little motley yellowish tissue on the surface of the liver which shows toxin damage. A real badly damaged liver is like a lump of wood.

But note especially the nice new healthy liver lobe on the right of the picture, and the 3 new small ones at the top right, and how healthy the internal tissue is.

For the last two seasons, this old ewe has been treated regularly with a zinc-based nutritional supplement which has protected her from further liver damage by toxins, and helped to stimulate new healthy liver growth.

Internal signs of a dysfunctional liver
Often at post mortem of a ewe dying close to lambing, you'll find two dead almost mummified lambs insider her but great masses of fat in the body cavity which the liver has not been able to process to nurture the lambs.

Facial Eczema (FE). Farmer Information. Part 3. (Dairy Cattle). Management.

Agriculture, farming, animal husbandry, animal heath, disease, Facial Eczema, Dairy cattle, management, advice, recommendations

By Dr Clive Dalton

Original 1991 information written by Dr Barry Smith and Dr Neale Towers, Ruakura Agricultural Research Station, Hamilton, New Zealand.

 
3. (Dairy Cattle). Management.

• Make early preparations - in December or early January.
•  Learn about spore counting - contact your veterinarian.
• Find out which are your worst paddocks (by spore counting) and avoid grazing them during danger periods.
• Never make stock graze into the base level of pastures. The fungus grows on the litter at the base of the pasture and the spores are concentrated there.
• Choose a prevention option from one of the following three:
•  (1). Spray pasture with fungicide. Check that spray unit is properly calibrated and purchase fungicide early.
• (2). Use a suitable zinc prevention method. If you have a suitable water reticulation system, add zinc sulphate. Otherwise dose with zinc oxide or spray zinc oxide on to pasture.
• (3). Provide supplementary feed (crops, fodder, hay or silage). Use to reduce grazing pressure on toxic pasture.
• Have a concentrated calving and calve early so that you have at least 80% of annual production in the six months to the end of January.
• Get rid of all surplus stock early before spore counts become high. This allows you to reduce grazing pressure for remaining stock. If things get worse dry off the herd.  This will immediately cut pressure on feed by half. It will also cut your income so it's an important decision.
• If replacement heifers are grazed off the farm make sure that the manager is taking adequate measures to protect them against FE.
• Care for affected stock by one of the following options:
• (1). Dry off milking cows.
• (2). Confine in shaded area, barn etc.
•  (3).Treat infected skin lesions.
• (4). Provide access to water and quality feed. Cattle with clinical FE will prefer to graze at night or in overcast conditions.

Disclaimer

This material is provided in good faith for information purposes only, and the authors do 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.

Facial Eczema (FE). Part 5. Farm Information.(Dairy Cattle). Zinc oxide. Long-term dosing.

Agriculture, Farming, animal husbandry, animal health, disease, Facial Eczema, advice on prevention, recommendations, zinc, zinc oxide, long-term dosing, recipes.

By Dr Clive Dalton

Original 1991 information written by Dr Barry Smith and Dr Neale Towers, Ruakura Agricultural Research Station, Hamilton, New Zealand.

5. Facial Eczema: (Dairy Cattle). Zinc oxide. Long-term dosing.

• Milking cattle are best dosed daily, this gives best protection and, once the cows are trained, causes less disruption in the shed.
• Milking cattle can be protected by dosing at 2 or 3 day intervals. Do not dose at greater than 3-day intervals as the high zinc doses will cause milk fever in a small proportion of the cows.
• Dry cattle can be dosed twice weekly, or at weekly or fortnightly intervals.
• Dose rates need to be increased to account for less efficient protection and the length of interval between doses if not dosed daily.
• Zinc oxide dosing can be expected to markedly reduce, but not totally prevent, FE outbreaks.
• Daily dosing should reduce the number of animals affected and the severity of the damage to the livers of affected animals by 80-90%.
• Twice-weekly (lactating) and weekly dosing (dry stock) by 70-80%.
• A more stable and concentrated drench can be made by including either a commercial stabiliser such as CoZinc (Coast Biologicals Ltd) or Maximix (Bell-Booth Ltd), or a liquid "farm" strength seaweed fertiliser such as Maxicrop (Bell-Booth Ltd), Green Label Response (Coast Biologicals Ltd) or Sea Magic (Yates Ltd).

Remember: Not all liquid fertilisers are seaweed based.

• Stabilisers have two advantages:
• (1). They increase the ease of mixing and drenching.
• (2). They allow the mixing of more concentrated drenches and therefore use of smaller drench volumes.
• Make sure you use the right dose rate for the type of drench mixed.

Note: Proprietary mixes such as Cozinc (Coast Biologicals Ltd), Maximix (Bell-Booth Ltd) and Nu Zinc (Nufarm Ltd) should be mixed and used as recommended on the product label.

Recipes
Unstabilised drench

• Mix 1 kg zinc oxide with 2.5 litres of water.
• Sprinkle powder on water and leave to wet.
• Stir until smooth and lump free.
• If too stiff to flow through drench gun, add a little more water.
• If too thin to stay in suspension, stir in a little more zinc oxide powder.
• This produces about 2.7 litres of drench.

• Daily dosing: 7 ml/100 kg liveweight.
• 3-day, weekly: 10 ml/100 kg liveweight x No. of days between drenches

Stabilised drench

• Mix 1 kg zinc oxide powder with 1 litre of water and 200 ml of "stabiliser".
• Mix the stabiliser and water first.
• Sprinkle powder on the water and let settle and wet.
• Stir to a smooth creamy paste.

• Daily dosing: 3.6 ml/100 kg liveweight.
• 3-day-weekly: 5ml/100 kg liveweight x No. of days between drenches.

Disclaimer
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.

Facial Eczema (FE). Farm Information. Part 4.Zinc oxide. General dosing information.

Agriculture, farming, animal husbandry, animal health, disease, Facial Eczema, prevention, zinc oxide, general dosing information, zinc, toxicity, copper, selenium

 By Dr Clive Dalton

Original 1991 information written by Dr Barry Smith and Dr Neale Towers, Ruakura Agricultural Research Station, Hamilton, New Zealand.

4. FACIAL ECZEMA:  Zinc oxide. General dosing information.  

When to Start

•  Have supplies of Zinc Oxide and the equipment needed ready well before the FE season starts. Supplies can be difficult to buy during an FE outbreak.
•  Zinc dosing should begin as soon as the weather conditions (warm, humid, grass minimum temperature more than 13"C, heavy dew or 3-4 mm rain) favour spore growth and/or at the first signs that spore counts are beginning to rise. Don't wait until dangerous conditions arise, or until clinical cases are seen. 
• The spore rises precede clinical symptoms by some 10-1 4 days, and to be effective zinc must be dosed before or at the time the animals graze toxic pasture. 
• Farmers regularly monitoring spore counts early in the season could delay starting dosing until counts begin to rise (don't wait until they reach danger level). It usually takes more than a week for the earliest spore rise of a season to reach danger levels, so starting dosing immediately spore rises begin should provide adequate protection.
• On problem farms in particular begin dosing in mid-January and continue throughout the autumn. 
• Stock should not be exposed to zinc unnecessarily and excessively prolonged zinc dosing lowers the safety margin.
  

How to Start

• Begin dosing at long-term dose rates unless dangerous conditions already exist.
•  If conditions become dangerous during the first week of dosing increase the dose rate to "crisis" levels. Keep dose rates at this level for two weeks then reduce to long-term dose rates.
  

When to Stop

• Continue dosing through the expected FE season.
•  Towards the end of the FE season dosing can stop when spore counts fall to low levels and weather conditions are dry and cool. But watch the weather and start dosing if conditions favour spore growth again.
• After long-term zinc dosing ceases, protection will carry over for several days.
• After prolonged zinc dosing, protection will be quickly re-established once zinc administration begins again.
  

Zinc Toxicity

• Overdosing with zinc is toxic. Take care calculating dose rates, weighing zinc and mixing drenches. Check drench guns for accuracy.
•  There is a 3-fold safety margin for dosing zinc over 60 days, i.e. if three times the recommended rate is given it will cause damage to the pancreas.
• The safety margin for dosing for longer periods is progressively reduced. Hence the need to use the correct dose rates, and avoiding unnecessary dosing for long periods.
• Pancreatic injury must be severe before effects on animal health are noted. The pancreas will recover when zinc dosing ceases.
• Administering zinc oxide drenches in large amounts as may occur with weekly or fortnightly dosing interferes with calcium metabolism (and may cause milk fever) and is not recommended for lactating stock.
• Because elevations of zinc occur in liver and kidney (not meat) a withholding period of 1 week should be allowed before animals are slaughtered.
  

Copper and Selenium

• Long-term zinc dosing may interfere with copper and selenium metabolism, although it has not yet been shown to induce copper or selenium deficiency.
•  In areas where these minerals are deficient supplement the animals with copper and selenium immediately after zinc administration ceases.
• Don't give copper supplements during the FE season unless clinical deficiencies exist. If copper supplements are required use an injectable preparation.
  

Purity of Zinc Compounds

• Ask the supplier if the zinc oxide meets the Animal Remedies Board's specifications.

General
A volumetric measure of the zinc oxide is sufficient when mixing. Weigh out the zinc oxide needed to dose all animals, smooth the surface and mark the surface height on the container. An independent check of calculations should be made and professional advice sought if there is any doubt about the methods.


Disclaimer
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.

Facial Eczema (FE). Farmer Information. Part 6. (Dairy Cattle). Zinc oxide. Crisis dosing.

Agriculture, farming, animal husbandry, animal health, disease, Facial Eczema, dairy cattle, dosing in crisis, zinc, dose rates

 By Dr Clive Dalton

 

Original 1991 information written by Dr Barry Smith and Dr Neale Towers, Ruakura Agricultural Research Station, Hamilton, New Zealand.
 

6. FACIAL ECZEMA: (Dairy Cattle). Zinc oxide. Crisis dosing.

• Where the danger of FE does not normally warrant routine zinc oxide dosing, cattle can be protected by dosing during danger periods only, i.e. "Crisis dosing".
•  Crisis dosing gives less protection than long-term routine dosing and therefore requires higher dose rates to give adequate protection.
•  Daily dosing during danger periods will reduce the number of animals affected and the severity of the liver damage in affected animals by about 60%.
• Crisis dosing is best restricted to daily or at most twice weekly dosing. 
• Zinc oxide drenches can be prepared with or without a seaweed based "stabiliser".
•  Stabilisers have two advantages:
• (1). They increase the ease of mixing and drenching.
•  (2). They allow the mixing of more concentrated drenches and therefore use of smaller drench volumes.

Unstabilised drench
Recipe

• Mix 1 kg zinc oxide with 2.5 litres of water.
•  Sprinkle powder on water and leave to wet.
•  Stir until smooth and lump free.
•  If too stiff to flow through drench gun, add a little more water.
•  If too thin to stay in suspension, stir in a little more zinc oxide powder.
• This produces about 2.7 litres of drench.

Stabilised drench
Recipe

• Mix 1 kg zinc oxide powder with 1 litre of water and 200 ml of "stabiliser".
•  Mix the stabiliser and water first.
•  Sprinkle powder on the water and let settle and wet.
•  Stir to a smooth creamy paste.
•  This produces about 1.4 litres of drench.

Use liquid "farm" strength seaweed fertilisers as stabilisers such as Maxicrop
(Bell-Booth Ltd), Sea Magic (Yates Ltd) and Green Label Response (Coast
Biologicals Ltd).

Dose Rates

• Unstabilised drenches: 10 ml/100 kg liveweight.
• Stabilised drenches: 5 ml/100 kg liveweight

Approximate daily dose volumes - Crisis dosing

• If dosing at 2- or 3-day intervals, multiply the daily dose rate by the number of days between doses.

Note: Proprietary mixes such as Cozinc (Coast Biologicals Ltd), Maximix  (Bell-Booth Ltd) and
 Nu Zinc (Nufarm Ltd) should be mixed and used as recommended on the product label.

Some motor-driven drenching systems cannot be adjusted to the recommended dose
volumes. Therefore the drench mixture must be adjusted so that the correct amount of
zinc oxide is given.

Disclaimer
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.

Facial Eczema (FE). Farmer Information. Part 9. (Sheep). Zinc oxide. Long-term dosing.

Agriculture, farming, animal husbandry, animal health, disease, Facial Eczema, preventoin, zinc, zinc oxide, dosing, long-term dosing, recipes.

By Dr Clive Dalton

Original 1991 information written by Dr Barry Smith and Dr Neale Towers, Ruakura Agricultural Research Station, Hamilton, New Zealand.

9. Facial Eczema: (Sheep). Zinc oxide. Long-term dosing.

• Sheep should be dosed regularly with zinc oxide throughout late summer and autumn period.
• Zinc dosing should start at least 2 weeks before dangerous conditions normally occur. In most districts this means dosing should start in early to mid January.
• Dosing should continue until cooler winter weather conditions occur.
• Protection can be obtained buy dosing twice weekly, or at weekly or fortnightly intervals. However, at the longer dosing intervals lower levesl of protection can be expected.
• Weekly dosing should reduce liver damage by 60-70%.
• Dosing at 2-week intervals will give less protection and reduce liver damage by about half if carried out regularly during the FE season.
• If dosing at 2-week intervals, the next zinc oxide dose should be brought forward if a danger period occurs in the last half of the interval.
• Dosing at 2-week intervals has on occasion been associated with salmonellosis outbreaks. Where this has been a problem, a maximum dosing interval of 1 week is recommended.
• Zinc oxide drenches can be prepared with or without a seaweed “stabliser”.

• Stablisers have two advantages:
• (1). They increase the ease of mixing and drenching.
• (2). They allow the mixing of more concentrated drenches and therefore use smaller drench volumes.
• Recipes and dose rates of both types of drenhches are provided below. Make sure you use the right dose rate for the type of drench mixed.
  

Note: Proprietory mixes such as Cozinc (Coastal Biologicals Ltd), Maximix (Bell-Booth Ltd) and Nu Zinc (Nufarm Ltd) should be mixed and used as recommended on the product label.

Unstabilised drench

Recipe

• Mix 1 kg zinc oxide with 2.5 litres of water.
• Sprinkle powder on water and leave to wet.
• Stir until smooth and lump free.
• If too stiff to flow through drench gun, add a little more water.
• If too thin to stay in suspension, stir in a little more zinc oxide powder
• This produces about 2.7 litres of drench.
  

Stabilised drench
A more stable and concentrated drench can be made by including either a commercial stabiliser such as CoZinc (Coast Biologicals) or Maximix (Bell-Booth Ltd), or a" farm" strength liquid seaweed fertiliser such as Maxicrop (Bell-Booth Ltd), Green Label Response (Coast Biologicals Ltd), Sea Magic (Yates Ltd).

Recipe

• Mix 1 kg zinc oxide with 1 litre of water and 200 ml of "stabiliser".
• Mix the stabiliser and water first.
• Sprinkle powder on the water and let settle and wet.
• Stir to a smooth creamy paste.
• This produces about 1.4 litres of drench.
  

Dose rates:

• Unstabilised - 1 ml/10 kg liveweight x no. of days.
• Stabilised - 0.5 ml/10 kg liveweight x no of days.
  

Approximate dose volumes:

Footnote 2009: Zinc boluses are now available. Contact your veterinarian for information.

Disclaimer
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.

Facial Eczema (FE). Farmer Information. Part 7. Zinc Oxide. Motor-driven Drenching Systems

Agriculture, farming, animal husbandry, animal health, disease, Facial Eczema, advice, recommendations, zinc, zinc oxide, motor driven drenching systems, methods

By Dr Clive Dalton

Original 1991 information written by Dr Barry Smith and Dr Neale Towers, Ruakura Agricultural Research Station, Hamilton, New Zealand.

 Part 7. Facial Eczema. Zinc Oxide. Motor-driven drenching systems

 Some motor-driven drenching systems cannot be adjusted to the recommended dose volumes. Therefore the drench mixture must be adjusted so that the correct amount of zinc oxide is given.


Method
-
Establish the drench volume/cow.

• Deliver a set number of shots into a measuring jug.
• Record the total volume.
• Divide the total volume by the number of shots to get the shot volume.
• e.g. 10 shots equals 550 ml
• Shot volume = 550 +- 10 = 55 ml
• Repeat at least once to confirm the result.
  

Determine the correct zinc oxide dose per cow from the table below.

Note. These rates give the same zinc dose as the other zinc drenches.
These rates are higher than recommended in AgLink FPP 496.

• Subtract 3 ml from drench shot volume to compensate for the volume of the zinc oxide, e.g. 55 ml - 3 = 52 ml.
•  Multiply volume and the zinc oxide dose rate by the number of cows, e.g. 100 cows x (10 g zinc oxide + 52 ml water) = 1 kg zinc oxide + 5.2 litres water (1 kg + 5 litres rounded off).
• Multiply the daily mix by the number of days, e.g. for 20 days = 20 kg zinc oxide + 100 litres water.
• Most farmers would prepare a bulk mix of a 20 kg bag of zinc oxide.
  

Note: In mid-season, check your zinc supplies and your arithmetic to make sure you
have not been overdosing.

• e.g. 100 cows (J x F) @ 10 g/day for 50 days = 100 x 10 g x 50 days = 50 000 g (50 kg).
•  Have you used more or less than 50 kg zinc oxide so far?
  

Disclaimer
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.

Facial Eczema (FE). Farmer Information. Part 8. Zinc oxide. Prevention by pasture spraying.

Agriculture, farming, animal husbandry, animal health, disease, Facial Eczema, prevention, pasture spraying, zinc oxide.

By Dr Clive Dalton

Original 1991 information written by Dr Barry Smith and Dr Neale Towers, Ruakura Agricultural Research Station, Hamilton, New Zealand.

8. FACIAL ECZEMA: Zinc oxide. Prevention by pasture spraying.

• Spraying zinc oxide onto pasture before it is grazed provides a method of dosing large numbers of animals with a relatively low labour input.
•  The method requires an area of sprayable land with sufficient pasture to provide grazing for a 12 or 24 h period.
• The method works best when the grazing area is small and t he pasture is moderately long so that the percentage utilisation of the pasture is high.
• A high pasture utilisation is needed to ensure that most of the zinc oxide is actually eaten by the grazing animals.
• Dry stock can be protected by spraying pasture either once or twice a week.  Milking cows are best protected by spraying pasture daily - but note that the need to restrict grazing to maximise zinc intakes will affect production.
• Milking cows could be protected by grazing sprayed pasture at 3-4 day intervals, but should not be given weekly doses of zinc oxide as this is likely to interfere with calcium metabolism and cause milk fever.
• The method is not suitable for calves, which require lax grazing for good liveweight gains.
• The major advantage with zinc oxide spraying is that it can give immediate protection when conditions are dangerous. Spraying fungicides may be more convenient and not much more costly.
  

Procedure

• Spray or dust a restricted area sufficient for 12 or 24 hours hard grazing.
• Graze animals at stocking rates ensuring maximum pasture utilisation. Confine animals to the sprayed area.
• Choose application rates to match the dosing interval (daily, twice weekly, weekly) and the estimated pasture utilisation expected (see tables below).
• Any spraying system (boom or rose) with a high return flow through the bypass valve is adequate for applying zinc oxide. The high return flow is required to keep the zinc oxide in suspension; with an inadequate flow there is a danger of the zinc oxide settling and blocking inlets etc.
• Continue spraying the area until all mixture is applied. Use largest possible nozzles and spray flow rates.
  

Mixing

• If a high-pressure water supply (yard washing system) is available pour the dry zinc oxide into the spray tank (place a piece of timber over the pump inlet first to prevent blocking) and use the high pressure water jet to disperse the powder while filling the tank.
•  Alternatively, mix 5 kg lots into a slurry by hand and add to partly filled spray tank. It is easiest if the dry powder is poured onto water in bucket and left to settle before stirring. Don't pour water onto the powder.
  

Amount of Zinc Oxide to Use

• Dose rates should be adjusted to compensate for changes in pasture utilisation as this controls the proportion of the zinc oxide applied that is actually eaten.
•  Most of the zinc oxide will be on the upper parts of the sward. Zinc oxide ingestion is about 20 percent higher than the pasture utilisation.
• On shorter autumn pastures utilisation rates of about 30-35 percent can be expected.
• Choose the dose rate that best matches your estimates of pasture utilisation and average liveweight for your herd from the table below.
• Multiply the daily dose rates by the number of animals to be treated.
  

Example:

• For a 160 cow F x J herd with average weight of 400 kg eating about a third of the grass' offered.
•  Daily dose rate = 20 g.
• Total zinc oxide required 20 x 160 = 3200 g = 3.2 kg
  

 (Note: Not recommended for calves).

• Daily spraying should have minimal effect on pasture palatability although cattle may show some initial reluctance to graze.
•  Milking cattle can be protected by grazing zinc-oxide-sprayed pasture at 2 to 4 day intervals, but the dose rates need to be increased to compensate for the less effective protection.
• If dosing at 2-, 3- or 4-day intervals multiply the daily dose rates by 2.5, 4 or 5.5.
•  Other classes of stock can be protected by grazing pastures sprayed with zinc oxide once a week. This is not recommended for milking cows.
• Cattle and sheep grazing pastures sprayed once weekly, may show reluctance to graze the pasture. It may be necessary to confine them to the sprayed area for more than 24 hours - check final pasture utilisation and adjust spray rates to match.
• The table below shows the amount of zinc oxide to use for other classes of stock and various levels of pasture use.
• If the pasture utilisation rate is not known assume a 30% rate.

Disclaimer
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.

Facial Eczema (FE). Farmer Information. Part 10. (Dairy cattle). Zinc sulphate. In drinking water.

Agriculture, farming, animal husbandry, animal health, disease, Facial Eczema, prevention, zinc, zinc sulphate, administered in drinking water, zinc toxicity, copper and selenium.

By Dr Clive Dalton

Original 1991 information written by Dr Barry Smith and Dr Neale Towers, Ruakura Agricultural Research Station, Hamilton, New Zealand.

10. Facial Eczema: (Dairy cattle). Zinc sulphate.  In drinking water. 

Administering zinc sulphate via the drinking water is a very effective way of preventing FE in dairy cattle. There are four main methods of adding zinc sulphate to the drinking water of cattle.

• Using an in-line dispenser to add a concentrated solution of zinc sulphate into the water reticulation system.
•  Adding zinc sulphate to a large tank (e.g. 22,000 litres, or 5,000 gals) which supplies the water reticulation system.
  

These are the preferred methods where the stock drinking water can be isolated from other uses of water on the farm.

• Floating trough dispensers - large numbers of animals can be protected but there is less control of concentration than the other methods and the troughs may require twice-daily attendance.
•  Direct addition to the water trough - this will only cope with very small numbers of animals.
  

Note: The addition of zinc sulphate to the water supply is only suitable to long-term routine dosing - it is not suited to "crisis" dosing during danger periods.

Water Reticulation

• It is essential that zinc-medicated water is reticulated only to the livestock.
•  Household water supplies and dairy shed water must be kept separate.
•  Non-return valves may be necessary to avoid siphoning or back-flow problems, and water pressure and flow rates should be within the capacity of the diluting equipment being used.
  

Alternative Water

• Except in the first day or two, cattle will not refuse zinc in drinking water at the recommended rates. However, they are will prefer un-medicated water to zinc treated water if given the choice.
•  Make sure that livestock do not have access to alternative fresh water during the period that zinc is being added for FE control.
  

When to Start

• Have supplies of ZINC SULPHATE and the equipment needed ready well before the FE season starts.
•  Zinc dosing should begin as soon as the weather conditions (warm, humid, grass minimum temperature more than 13"C, heavy dew or 3-4 mm rain) favour spore growth and/or at the first signs that spore counts are beginning to rise.
• Don't wait until dangerous conditions arise, or until clinical cases are seen.
• Remember that the spore rises precede clinical symptoms by some 10-14 days,  and to be effective zinc must be dosed before or at the time the animals graze toxic pasture.
• Farmers regularly monitoring spore counts early in the season could delay starting dosing until counts begin to rise (don't wait until they reach danger level). It usually takes more than a week for the earliest spore rise of a season to reach danger levels, so starting dosing immediately spore rises begin should provide adequate protection.
• On problem farms in particular begin dosing in mid-January and continue throughout the autumn.
• Stock should not be exposed to zinc unnecessarily and excessively prolonged zinc dosing lowers the safety margin.
  

How to Start

• Cows should be introduced to increasing zinc concentrations in water over a period of about 3-5 days. Use one quarter the required dose on day 1, half on day 2, three quarters on day 4, etc. Increase the rate more quickly if spore counts are rising rapidly.
•  Troughs on the reticulated system in paddocks that have not been grazed should be primed with zinc sulphate at the rate of 1 gram/litre (0.7 gram/litre monohydrate).
  

When to Stop

• Continue dosing through the expected FE season. 
•  Towards the end of the FE season dosing can stop when spore levels fall to low levels and weather conditions are dry and cool. But watch the weather and start dosing again if conditions favour spore growth again.
• If possible avoid dosing continuously for more than 100 days.
• After long-term zinc dosing ceases, protection will carry over for several days.
  

Zinc Toxicity

• Overdosing with zinc is toxic. Take care calculating dose rates and weighing or measuring the zinc sulphate.
•  There is a 3-fold safety margin for dosing zinc over 60 days, i.e. if three times the recommended rate is given it will cause damage to the pancreas after about 60 days.
• The safety margin for dosing for longer periods is progressively reduced. Hence the need to use the correct dose rates, and avoiding unnecessary dosing for long periods.
• Pancreatic injury must be severe before effects on animal health are noted. The pancreas will recover when zinc dosing ceases.
• Direct addition of zinc sulphate to the trough or poorly designed dispensers can result in very high zinc concentrations in the water immediately after the zinc sulphate is added. This can give excessive intakes to animals drinking this water.
• Later drinking animals can be under-dosed and be left unprotected as incoming water progressively dilutes the zinc concentrations in the trough.
• Because elevations of zinc occur in liver and kidney (not meat) a withholding period of 1 week should be allowed before animals are slaughtered.
  

Lactating and Dry Stock

• When lactating and dry stock are watered from the same water source where zinc is added, the lactating cows will receive a higher daily intake of zinc because of their higher water requirements. 
• On a weight basis, their consumption of grass and hence spores will also be higher.
  

Copper and Selenium

• Long-term zinc dosing may interfere with copper and selenium metabolism, although it has not yet been shown to induce copper or selenium deficiency.
•  In areas where these minerals are deficient supplement the animals with copper and selenium immediately after zinc administration ceases.
• Don't give copper supplements during the FE season unless clinical deficiencies exist.  If copper supplements are required use an injectable preparation.
  

Purity of Zinc Sulphate
The most commonly used form of zinc sulphate is the heptahydrate; this is generally coarse greenish crystal. Also available is the monohydrate form; this is normally a white powder or fine crystal and is freer flowing. It is used at two-thirds the dose rate of the heptahydrate.

Ask the supplier if the zinc sulphate meets the Animal Remedies Board's specifications.


Disclaimer
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.

Facial Eczema (FE). Farmer Information. Part 11. (Dairy cattle). Zinc sulphate. Using in-line dispenser.

Agriculture, farming, animal husbandry, animal health, disease, Facial Eczema, prevention, dairy cattle, zinc sulphate, using in-line dispensers, dairy cattle.

By Dr Clive Dalton

Original 1991 information written by Dr Barry Smith and Dr Neale Towers, Ruakura Agricultural Research Station, Hamilton, New Zealand.

11. FACIAL ECZEMA: (Dairy cattle). Zinc sulphate.  Using in-line dispenser.

There are a number of in-line dispensers or dilutors available commercially. Those, which add a constant proportion of a concentrate into the reticulation system, will give best control of dose rates. While it is not necessary to know exactly what the dilution rate is, those systems with variable dilution rates will be easier to set up to provide the correct dose rates.

Equipment Required

In-line dispenser

• Check that it will function with the water pressures, flow rates and daily consumption expected for your property.
•  The dispenser should be installed in a sheltered position protected from frost, and at a convenient location for daily refilling.
•  The dispenser is best installed on a by-pass line so it can be disconnected when not required without interrupting the water supply.
•  The dispenser should be downstream of household or dairy shed water draw-off.
•  A source of water will be required for refilling the concentrate tank.
•  Fit an in-line filter if your water supply is sandy or gritty to protect the working parts of the dispensers.

Zinc sulphate concentrate reservoir

• A tank or drum equipped with a sight glass and holding enough concentrate to last between servicing. Alternatively a dip stick can be used to measure the tank contents.
•  The size of the tank can be estimated by dividing the maximum daily water consumption of the herd by the dilution ratio of the dispensing unit.

Example:
200 cow herd @ 100 litres drinking water/cow/day (maximum) using a unit which adds 1 part concentrate to 128 parts of water.

Concentrate tank size - 200 x 100/128 = 156 litres .

The concentrate tank may be larger than the calculated volume.

Getting Started
1. Set the daily refilling level on the concentrate reservoir.
2.   Adjust the dispenser (or tank volume) so that each day half to three-quarters of the solution in the concentrate reservoir is injected into the water supply each day.

Either

• Mark a temporary "FULL" line on the tank and fill to the mark with water.
•  Turn on dispenser and record the water level in the tank 24 hours later.
•  Refill and repeat two or three times.
•  Adjust the position of the "FULL" line or alter the dispenser dilution rate so that from one half to three-quarters of the water in the concentrate tank is used each day.
•  Mark two lines at one quarter and one half of the "FULL" line.

Or

• Measure the average daily draw-off from the concentrate tank filled with water.
•  The "FULL" line should then be marked at 1.5 times the average daily draw-off. Mark the half and quarter lines in the same way.

• Calculate the amount of zinc sulphate to be added each day.
• Multiply the dose rate for each class of livestock by the number of animals and total these figures.
  

Example:
How much zinc sulphate would a farm with 160 Friesian milking cows, 65 yearlings, and 40 calves need each day?

160 COWS x 36 g = 5760g
65 yearlings x 22 g = 1430g
40 calves x 15 g = 600g
Total = 7790 g = 7.8 kg

Two forms of zinc sulphate
There are two forms of zinc sulphate available.
(1). Zinc sulphate heptahydrate is the material commonly available.
(2). Zinc sulphate monohydrate is now also being sold; this is a more concentrated form of zinc sulphate and is used at two-thirds the dose rates used for the heptahydrate.

Once calibrated, a volumetric measure is sufficiently accurate for regular use.  Weigh out the required zinc sulphate into a plastic bucket. Level the surface and mark the height. Fill the bucket to this level each day.

Daily Maintenance

• At the same time each day, add the daily total amount of zinc sulphate to the concentrate reservoir.
•  Refill to the “FULL” line with clean water and stir to dissolve the zinc sulphate.
  

Twice-weekly or weekly maintenance

• An in-line dispenser can be used to protect stock at locations which cannot be serviced daily. In this case, the concentrate tank must be large enough to ensure that only half to three quarters of the concentrate is used in the intervals between servicing.
•  At each visit, add enough zinc sulphate to last until the next visit. So multiply the daily requirement by the number of days until next serviced.
• Refill the concentrate tank to the “FULL” line.
  

Fine Tuning

• Throughout the season adjust the position of the FULL and EMPTY lines or the dispenser dilution rate so that before refilling the concentrate level falls between the two lines on most days.
•  Do not be concerned about the occasional day when either more (a very hot dry day) or less (a wet day) concentrate is used.
• Adjust position of "FULL" and "EMPTY lines or dilutions rate only when the concentrate level is consistently outside these limits.
• If wet weather causes very low usage of the zinc concentrate for 2-3 days stop adding zinc sulphate for a few days until the concentrate level again drops to the half empty line.
  

WARNING
Concentrated zinc sulphate solutions are caustic. Wear protective goggle and avoid direct skin contact.

Disclaimer
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.

Facial Eczema (FE). Farmer Information. Part 12. (Dairy cattle). Zinc sulphate. Direct addition to supply tank

Agriculture, farming, animal husbandry, animal health, disease, Facial Eczema, prevention, zinc, zinc sulphate, dairy cattle, addition of zinc to supply tank.

By Dr Clive Dalton

Original 1991 information written by Dr Barry Smith and Dr Neale Towers, Ruakura Agricultural Research Station, Hamilton, New Zealand.

12. Facial Eczema: (Dairy cattle). Zinc sulphate.  Direct addition to supply tank

• On many farms trough water is drawn from a large supply tank which feeds water to the troughs at a constant pressure. 
•  Most tanks are at least 22 000 litre (5000 gal) capacity and, when the tank capacity is sufficient to provide more than the expected daily draw-off by stock, the zinc sulphate can be added direct to the tank (Fig.1).
• As a rule the tank should contain about 100 litres for every lactating cow or cow equivalent.

Procedure
To calculate the amount of zinc sulphate to be added each day.

• Use the table below to calculate the dose rate for each class of stock on the farm.
•  Then total these figures.
  

Example:
How much zinc sulphate would a farm with 160 Friesian milking cows, 65yearlings and 40 calves need each day?

160 COWS x 36 g =5760
65 yearlings x 22 g = 1430
40 calves x 159 = 600
Total = 7790 g = 7.8 kg

Two forms of zinc sulphate
There are two forms of zinc sulphate available.
(1). Zinc sulphate heptahydrate is the material commonly available.
(2). Zinc sulphate monohydrate is now also being sold; this is a more concentrated form of zinc sulphate and is used at two-thirds the dose rates used for the heptahydrate.

• Once calibrated, a volumetric measure is sufficiently accurate for regular use.  
• Weigh out the required zinc sulphate into a plastic bucket. 
• Level the surface and mark the height. Fill the bucket to this level each day.
  

Daily Maintenance

• Add the daily zinc sulphate to the supply tank at the same time each day.
•  The zinc sulphate should be dissolved in water before adding to the tank.
• If the supply tank is regularly refilled, e.g. by a pump on a time switch, the zinc sulphate should be added just after filling.
  

Twice-weekly or weekly maintenance

• If the supply tank is large enough to supply water for several days without emptying if the inlet is shut off, then it is not essential that zinc be added daily.
•  At each visit add enough zinc sulphate to last until the next visit, i.e. multiply the daily requirement by the number of days until next serviced.
• The greater the interval between servicing the greater the variation in zinc concentration in the supply tank and the greater the chance the water will occasionally be unpalatable to the stock.
• Service as frequently as possible - do not leave more than half the number of days needed to empty the tank.
  

WARNING
Concentrated zinc sulphate solutions are caustic. Wear protective goggle and avoid direct skin contact.

Disclaimer
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.

Facial Eczema (FE). Farmer Information. Part 13. (Dairy cattle). Zinc sulphate. Direct addition to trough.

Northumberland, farming, animal husbandry, animal health, disease, Facial Eczema, prevention, dairy cattle, zinc, zinc suplphate, direct addition to trough

By Dr Clive Dalton

Original 1991 information written by Dr Barry Smith and Dr Neale Towers, Ruakura Agricultural Research Station, Hamilton, New Zealand.

13. Facial Eczema: (Dairy cattle). Zinc sulphate.  Direct addition to trough.

Direct Addition to Trough

• Direct addition of zinc sulphate to the trough in the paddock may be undertaken when small numbers of animals are involved such as on small "life style" blocks and the average water consumed daily by the animals is less than two-thirds of the trough volume.
•  Adding zinc to the water trough is only suitable for protecting cattle - sheep don't drink enough water to ensure zinc intakes are high enough to give adequate protection. Dose sheep with zinc oxide.
•  Start early so that you can measure daily water intakes and introduce the zinc sulphate gradually before conditions become dangerous.
•  If spore counts are already dangerous or weather conditions favour fungal growth and rapid increases in spore counts, the troughs should be primed with zinc sulphate to bring the zinc concentrations up to the necessary level immediately.

Procedure

Priming the troughs

• Add 0.75 g zinc sulphate for every litre of trough volume (use 0.5 g/litre if using zinc sulphate monohydrate).
•  Example: for 400 litre trough add 300 g zinc sulphate.
•  Tie off ballcock, stir to dissolve zinc sulphate.
•  Remember to prime all troughs before use, e.g. when moving stock to new paddock.

Daily maintenance
Calculate the amount of zinc sulphate to be added to the trough each day.

• Multiply the dose rate for each class of livestock (Table 1) by the number of animals and total these figures.

Example:

• How much zinc sulphate would a 4 ha block with 2 suckling cows, 4 Friesian yearlings and 4 Friesian calves need each day?

2 F x J cows x 32 = 64g
4 F yearlings x 22 = 88g
4 F calves x 15 = 60g
Total = 212 g per day

• Add the zinc sulphate to the water trough and stir to dissolve.
•  Keep the ballcock tied off to prevent dilution of the zinc sulphate solution.
•  Refill the trough next day and add a further day's zinc sulphate.
•  Where the water pressure is low and trough refilling is slow the water supply can be left connected. There will be greater variation in zinc concentrations and intakes but good protection should still be obtained.
•  Where the cattle drink only a small part of the trough content each day replenishing the zinc and refilling the trough can be done less frequently than daily.
•  Multiply the daily zinc sulphate requirement by the number of days since the trough was last filled.
•  Add this amount of zinc sulphate and refill the trough.
•  Tie off the ballcock again until the next refilling.

Disclaimer
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.

Facial Eczema (FE). Farmer Information. Part 14. (Dairy cattle). Zinc sulphate. Using in-trough dispensers.

Northumberland, farming, animal husbandry, animal health, disease, Facial Eczema, prevention, dairy cattle, zinc, zinc suplphate, using in-trough dispensers, examples

By Dr Clive Dalton

Original 1991 information written by Dr Barry Smith and Dr Neale Towers, Ruakura Agricultural Research Station, Hamilton, New Zealand.


14. FACIAL ECZEMA: (Dairy cattle). Zinc sulphate.  Using in-trough dispensers.

• The use of in-trough dispensers will reduce some of the problems caused by the direct addition of zinc sulphate to the trough.
• These devices still permit variations in concentration of zinc in the trough and the units may need twice-daily attention. 
•  By comparison, the in-line methods cause smaller and more acceptable variations in zinc concentration and consumption.
• They are more convenient, requiring at most only a brief daily attendance at the one supply point.
• However, for the smaller herd, the dispensers have been refined and can give acceptable results if the makers instructions are followed.
• They are much cheaper devices, but less convenient than in-line methods.
  

Procedure

• Calculate the amount of zinc sulphate to be added to the trough daily.
•  Multiply the dose rate for each class of livestock (see table) by the number of animals and total these figures.
  

Example:
How much zinc sulphate would a 4 ha block with 2 suckling cows, 4 Friesian yearlings and 4 Friesian calves need each day?

2 F x J cows x 32 = 64g
4 F yearlings x 22 = 88g
4 F calves x 15 = 60g
Total = 212 g per day

• If attending the trough twice daily (preferred method for in-trough dispensers) add half the daily amount on each visit to the trough.
•  In-trough dispensers rely on the turbulence recreated by rapid inflows of water when the ballcock operates to ensure mixing of the zinc sulphate throughout the trough.
• Where flow rates are low occasional stirring of the trough will give better mixing and more even zinc intakes by all cows.
• Use the dispenser according to manufacturers’ directions.
  

Two forms of Zinc Sulphate

• There are two forms of zinc sulphate available. 
•  Zinc sulphate heptahydrate is the material commonly available.
• Zinc sulphate monohydrate is now also being sold; this is a more concentrated form of zinc sulphate and is used at two-thirds the dose rates used for the heptahydrate.
• Once calibrated, a volumetric measure is sufficiently accurate for regular use.
• Weigh out the required zinc sulphate into a plastic bucket. Level the surface and mark the height.
• Fill the bucket to this level each day. 

Disclaimer
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.

Facial Eczema (FE). Farmer Information. Part 15. (Sheep & beef cattle). Grazing management.

Agriculture, farming, animal husbandry, animal health, disease, Facial Eczema, zinc, sheep and beef cattle, grazing management, advice, recommendations

By Dr Clive Dalton

Original 1991 information written by Dr Barry Smith and Dr Neale Towers, Ruakura Agricultural Research Station, Hamilton, New Zealand.

15. Facial Eczema: (Sheep and beef cattle). Grazing management.

• Planned grazing can substantially reduce the risks of FE in hill country. Good planning is essential and it must start months in advance.
•  Identify the safe areas on your farm and aim to have a feed bank on these areas for the FE season.
• Learn about spore counting - contact your veterinarian.
• The best way to identify the safer areas on your farm is by regular spore counting over several years - but in the meantime the shady south facing faces are generally safest.
• Spore counts on easy rolling paddocks and those facing north are generally higher than those on southern faces.
• Fence the safer areas separately so that grazing of these areas can be controlled.
  

Safer Pastures

• Spore counts are generally lowest on hillsides of low fertility grasses like browntop, sweet vernal, Yorkshire fog and danthonia. Summer growing grasses like kikuyu or paspalum are also safer.
•  Slopes exposed to prevailing drying winds also tend to have lower spore counts -but remember that a change in wind flows may result in normally safe paddocks becoming dangerous and visa versa.
• Pastures that have been allowed to become rank during Nov-Jan and have a lot of standing dead leaf and grass stems also tend to have low spore counts. These pastures may not look good but have a value of their own in a FE season.
• Ryegrass-white clover dominant pastures are the most dangerous especially if they have been burnt off in a dry summer followed by light rains during a humid autumn.
  

Safer Grazing

• Avoid hard grazing.
•  The spores are concentrated in the litter at the base of the pasture so the harder the sheep graze the greater the risk of FE.
• Light grazing will require good early planning or you will quickly run out of paddocks. 

• Aim to:
•  (1). Maximise feed available on safer areas of the farm.
• (2). Minimise stock numbers.
• Spread animals widely if set stocked or use a fast rotation leaving a high residual pasture mass.
• Do not try to retain young stock into late summer and autumn just to reach higher carcass weights.
• Aim for an early, compact lambing so that you get an early weaning and the maximum number away at good weights before the FE season.
• MAF trials showed that keeping lambs until March increased the grazing pressures on the breeding ewes and made the subsequent FE outbreak much worse. 
• More ewes died and those that survived produced fewer lambs the following spring.  The losses far outweighed the added return from the six weeks' extra lamb growth.
• Cull other stock early.
• Consider using hay, silage or crops early rather than heavily graze pastures.  The spores in the autumn saved pasture will lose toxicity with time.
  

Summing Up

• Identify and fence the safer areas of your farm.
•  Build up a feed bank on these areas for the FE season.
• Graze these areas during FE danger periods.
• Use these areas of poorer quality feed for breeding cows, ewes etc to reduce the stocking pressure on other parts of the farm.
• Avoid heavy grazing.
• Quit non-capital stock early.

Disclaimer
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.

Facial Eczema (FE). Farmer Information. Part 16. (Goats). Management

Agriculture, farming, animal husbandry, animal health, disease, Facial Eczema, zinc, prevention, goats, management

 

By Dr Clive Dalton

 
Original 1991 information written by Dr Barry Smith and Dr Neale Towers, Ruakura Agricultural Research Station, Hamilton, New Zealand.

16. FACIAL ECZEMA: (Goats). Management.

• Goats are generally more resistant to FE than sheep, and their browsing habits make them less prone to ingesting spores. 
•  Milking goats are at greatest risk.
• Make early preparations - in December or early January.
• Learn about spore counting - contact your veterinarian.
• Find out which are your worst paddocks (by spore counting) - avoid grazing them during danger periods.
• Never make stock graze into the base level of pastures. The fungus grows on the litter at the base of the pasture and the spores are concentrated there.
• Spray pastures with fungicide.
• Check that spray unit is properly calibrated and purchase fungicide early.
• Use a suitable zinc prevention method. In highly toxic conditions use zinc oxide prevention as for sheep. There is no research information at present on effective dose rates for goats.
• Provide supplementary feed (crops, fodder, hay or silage). Use to reduce grazing pressure on toxic pastures.
• Get rid of all surplus stock early before spore counts become high. This will relieve pressure on the remaining stock.
• Early and compact kidding allows for early weaning and good growth before disposal of sale stock.
  

Care for affected stock.

• Confine in shaded area, barn etc.
•  Prevent or treat flystrike and infections which may occur.
• Provide access to water and quality feed. Goats with clinical FE will prefer to graze at night or in overcast conditions.

Disclaimer
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.

Facial Eczema (FE). Farmer Information. Part 17. (Deer). Management.

 Agriculture, farming, animal husbandry, animal health, disease, Facial Eczema, zinc, deer, management

By Dr Clive Dalton

Original 1991 information written by Dr Barry Smith and Dr Neale Towers, Ruakura Agricultural Research Station, Hamilton, New Zealand.

17. FACIAL ECZEMA: (Deer). Management.

• Red deer are more susceptible to FE than cattle. Fallow deer are more susceptible than sheep so they need more protection than Reds.
• Make early preparations - in December or early January.
• Learn about spore counting - contact your veterinarian.
• Find out which are your worst paddocks (by spore counting) - avoid grazing them during danger periods.
• Never make stock graze into the base level of pastures. The fungus grows on the litter at the base of the pasture and the spores are concentrated there.
• Choose an appropriate prevention option.
• Spray pastures with fungicide. Check that spray unit is properly calibrated and purchase fungicide early.
• Regular spraying with fungicides provides the most appropriate control method for preventing FE in deer.
• Start the spraying programme early while spore counts are low.
  

Zinc

• The effectiveness and safety of zinc as a prevention has not been researched.
•  If used, dose rates as for sheep (Fallow deer) and cattle (Red deer) should be followed.
• Because of low water intake, zinc in drinking water is not effective.
• Provide supplementary feed such as hay, silage, meal or crop. Use to reduce the grazing pressure on toxic pastures.
• Get rid of all surplus stock early before spore counts become high. This will relieve pressure on the remaining stock.
• Early and compact fawning allows for early weaning and good growth before disposal of sale stock.
  

Care for affected stock.

• Confine in shaded area, barn etc.
•  Provide access to water and quality feed. Deer with clinical FE will prefer to graze at night or in overcast conditions.
• Take care moving affected animals, temporary blindness may cause extreme distress and result in self-inflicted injuries.

Footnote 2009:  Zinc boluses are now available. Contact your veterinarian before using them on deer.

Disclaimer
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.

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.

Strategies

• 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.

Rams

• If no clinical signs, treat as for ewes and ewe lambs.
•  With affected animals, cull immediately as susceptibility to FE is highly heritable.

Disclaimer
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.

Facial Eczema (FE). Farmer Information. Part 19. (Sheep). Breeding. Buying FE resistant rams.

Agriculture, farming, animal husbandry, animal health, disease, Facial Eczema, prevention, breeding, genetics, FE resistant rams, buying rams, advice, recommendations

By Dr Clive Dalton

Original 1991 information written by Dr Barry Smith and Dr Neale Towers, Ruakura Agricultural Research Station, Hamilton, New Zealand.

'Piquet Hill' FE-resistant 2th rams, selected for FE resistance for 27 years

19. Facial Eczema: (Sheep).  Breeding. Buying FE resistant rams.

• Start breeding FE resistance into your flock. Why? Because it is a permanent gain,  adding value to your flock and makes other annual precautions easier and less critical.
•  Tolerance to FE is strongly inherited. About 40 percent of the differences in resistance to FE seen between individual animals is due to their sire.
• Therefore progress in selecting and breeding more resistant sheep can be rapid, and significant gains can be made in only a few years of concentrated selection.
• But remember always that breeding for resistance is a long term commitment - it will not provide an overnight solution to your FE problems.
• Work in the Ruakura Resistant flock shows that the proportion of animals able to withstand a standard toxin dose can be increased by at least 2.5 to 3.5 percent each year.
• AgResearch operates a performance testing service called RAMGUARD to identify the most FE resistant rams amongst those tested by the breeders tested mob.
• Ram breeders using the RAMGUARD FE testing service for six years have doubled the resistance level of their flocks.
  

Ram Buyers

• Begin buying your rams from a breeder selecting for FE resistance using the RAMGUARD FE resistance testing service.
•  If your current ram breeder is not testing for FE resistance either:
• (1). Persuade him/her to start testing.
• (2). Change to a breeder who is.
  

Buying FE Resistance Rams

• Buy only from breeders who are selecting for FE resistance.
•  You should be consistent in this. You can lose the gains you have made if you bring in susceptible sheep from untested flocks.
• Select a ram breeder with sheep suited to your type of country, and with the conformation and production traits you want in your flock. Make sure he/she is committed to doing a good job selecting for FE resistance and is not just "window-dressing" to secure ram sales.
• It is not sufficient to hear the breeder say he is testing for FE resistance. You have to check out the programme and be sure that the rams you buy share the resistance that has been developed.
  

Check the following points:

• The number of rams tested and the number used as sires. The more rams tested and the smaller the percentage used as sires the faster progress should be.
•  Whether the breeder has used RAMGUARD to identify the most resistant 5, 10,  20 or 50 percent of the rams tested.
• Breeders using rams from the top 5 percent will make faster progress than those selecting rams from the top 50 percent.
• Check that only rams from the top resistant group are used as sires in the breeder’s flock.
• Using rams from low on the FE resistance ranking because they have high wool weights etc will slow down progress.
• Check what priority the breeder places on FE resistance to see if it matches your priorities. Placing a high priority on FE may slow progress for the other traits and vice versa.
• How many ram crops have been tested. So long as a sound selection programme has been established, the longer the breeder has been testing the further he will have progressed.
• The number of breeders with established FE selection programmes is relatively small at present so your choice of breeders may be limited to those who have only recently started selection for FE resistance.
• But remember, how well a breeder is selecting for FE resistance is more important than how long he has been testing.
• A new breeder testing a large number of rams and only using the most resistant rams will quickly overtake a breeder who tests only a few rams and/or uses rams from low on the resistance ranking list.
• Above all make sure that the rams you buy are sired by tested facial eczema resistant rams.
• Having found a breeder in whom you have confidence, stick with him/her.  Your progress will parallel their flock with you trailing by 2 or 3 seasons.
• Be prepared to pay a premium for rams from breeders running a sound FE selection programme. You will benefit from more resistant stock, better production and fewer losses. The breeder has high testing costs to meet in selecting resistant sires.

Disclaimer
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.