Woolshed 1: zinc

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May 12, 2009

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.

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?

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 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.

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.

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.

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.

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.

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May 12, 2009