While many areas of the Hunter have not had sufficient rain to create such conditions, the heavy falls in places like Gloucester and Bulahdelah may have created conditions suitable for kikuyu to become poisonous.

The nature of the poison remains uncertain, but cases of kikuyu toxicity can generally be avoided by providing the cattle with alternative feed during the period of risk, which usually only lasts a month.

An unfortunate complication at the moment is that livestock owners seeking to buy a few large bales of hay or silage to put out in kikuyu paddocks to reduce the risk to grazing cattle may have difficulty sourcing such feed at the moment.

For producers in the Upper Hunter, the variable showers that have occurred may have created an alternative plant poisoning risk: ingestion of rock fern*. Rock fern is drought tolerant, and the dormant fern revives within 24 hours of rain.

This means it is often the first green plant available after rain, and consequently attractive to grazing livestock. Rock fern contains two toxins which generate different poisoning syndromes in cattle (bleeding disorder) and sheep/horses (nervous disorder). Cattle normally need to eat rock fern for 2 weeks before signs of poisoning occur. Prevention involves removing them from risky country, or providing something more attractive to eat. Again, availability of decent quality hay and silage might presently be difficult.

* Note: bracken fern contains the same poisons as rock fern in greater quantities, so is an even greater risk.

Finally, those livestock owners who believe their livestock are at risk from kikuyu or rock fern poisoning and manage to obtain decent hay or silage to offer their animals need to be careful not to kill them with nitrate or prussic acid (cyanide) in the hay/silage. For all ruminants, introduction to a new type of feed needs to be gradual.

There have been many cases of nitrate poisoning during the last few years of drought when hungry cattle have been offered sudden access to hay (often very good quality hay). The same hay has caused no problems to cattle that have been adapted to it gradually. The nitrate levels in hay are fixed (ie they do not decline over time), while nitrate levels in silage do decline.

Nitrate deaths on silage have tended to occur when the silage has only recently been wrapped. Feed analysis to measure nitrate and prussic acid levels are presently free of charge at Hunter LLS, although it does take a week before the results are available.

It would be a shame to bring livestock through this drought only to have them succumb to kikuyu, fern or nitrate poisoning just when there is some light at the end of the tunnel. Please contact your local Hunter LLS District Vet or Livestock Officer to obtain more information and arrange feed testing on 1300 795 299 or visit us online at https://hunter.lls.nsw.gov.au/

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