Beef Cattle Facial Eczema
A disease of sheep, goats, cattle, and deer, caused by a fungus ‘Pithomyces chartarum’ that lives at the base of pasture plants. Under the right climatic conditions (grass minimum temperature of greater than 12-13 degrees centigrade, plus moisture and shelter from wind and direct sun, plus the presence of dead plant material), this fungus produces large numbers of spores for its own reproduction.
Unfortunately for herbivores with a bile system in the liver, these spores are toxic to the cells lining the bile system in the liver. The toxin is called Sporidesmin.
Damage caused by this toxin tends to be cumulative, ie each bit of damage is built upon by the next toxic insult, rather than the cell damage recovering between episodes. The fungus produces spores in waves, there are peaks and troughs of the numbers of spores throughout the season, these peaks are governed by the weather conditions. The first peak, which can be as early as December, is nearly always not dangerous. Unfortunately, the trough that follows is not as low as before the first peak, so the next peak is higher, and so on to the third and fourth peak. So, not only is the damage from each wave cumulative (even though the spore numbers may be below the danger level on each wave, if there are enough waves the damage to the liver is still significant), generally each successive wave exposes the animal to higher numbers of spores.
Remember, one of the conditions for the fungus to produce spores is the presence of dead plant material. Therefore, the safest paddocks are the exposed (west and south facing), poorly sheltered, clean paddocks.
Another factor is the level that the animals are grazing to. The lower they graze down to soil level, the more spores they eat. So safer pasture is also longer pasture, even though it may have a lot of litter at its base.
HOW TO PREVENT FACIAL ECZEMA
- Graze animals on safe’ pasture exposed, longer leaves, no shelter.
- Spray an area of pasture with a product that will decrease the number of spores produced by the fungus, and maintain animals on this sprayed pasture (with supplementary feeding if necessary) over the danger period. These sprays usually last around 5 – 6 weeks and are safe to graze immediately after spraying; however, to maximise the effect of the spray, are best grazed no sooner than 5 days after applying the spray. (eg ‘Topsin’, ‘Protek’)
- Graze stock on summer/autumn crops, maize, rape, choumoellier, turnips, pasja, etc.
- Zinc salts have a protective action on the cells affected by sporidesmin in the liver. Zinc sulphate can be used in water trough treatment; zinc oxide can be used for oral drenching, this includes the ‘Time Capsules’. See your Vet for dose rates, timing and frequency of dosing for various species.PREVENTION REQUIRES PLANNING
- The most important step a farmer can take is to plan a strategy to use should conditions favour the development of the spores of FE.
- The second most important step is to monitor trigger factors associated with the development of spores.
- The third most important step is to implement the planned strategy early in the development of the fungus.
- The fourth most important step is to not stop implementing the strategy until the risk has completely gone.
- Destocking – sell flexible stock
- Send capital stock to grazing in safe area
- Sell stock least likely to increase in value
- Cull least productive stock
- Selectively underfeed (eg dry stock)
- Supplementary feed – but graze out pastures fully first
- Prioritise stock (eg feed young growing stock well)
- Focus on tail-end stock (this group show the greatest returns on input)
- Graze out danger paddocks before spore counts rise , and save safe’ paddocks for grazing in danger periods (eg safe’, exposed pastures/south facing pastures/clover,fescue,chicory pasture/low litter pasture)
- Graze summer/autumn fodder crops during danger periods – but try to avoid grazing these before they are mature (fodder crops usually double their dry-matter content in the last 3-4 weeks of growth , a waste if used too early)
- When grazing safe pastures during danger periods, try to leave high residuals
- Dispose of other culls
- Dairy cows – once-a-day milking if cows producing < 0.7kg MS/day
- Selectively dry-off – young cows/low condition score animals
- Pasture spraying. Very effective so long as all of paddock sprayed. Can put higher stock numbers on than normal. See above.
- Water treatment with Zinc sulphate. Requires that stock do not have access to alternative (untreated) water supply.
- In-line dispensers – the best of this method. Important that not treating house and dairy shed water supply.
- Water trough dispensers – require twice a day supervision/top-ups. Can shift from trough to trough.
- Direct addition to water trough – need to tie up ball-cock to prevent dilution. Thus need to constantly check that stock have not run out of water; and need to top-up more often.
- Oral dosing of stock – with zinc oxide. See other notes for species dose rate and frequency. Includes ‘Time Capsules’.
For best results, treat before spore counts rise significantly; begin zinc at low dose rates; increase zinc as risk increases; beware of effect on copper; graze high risk areas at low risk time; and stop only when safe.
Trigger factors to monitor.
- History of property
- Weather patterns
- Soil temperature (minimum)
- Current pasture covers
- Current pasture quality
- Predicted pasture growth rate
- Predicted weather
- Market trends
- Cow condition
- Current production
- District FE spore counts and trends
- Property spore counts