Two horses died recently near Picton, with suspicion falling on the contents of a meal given to the horses before their deaths.
A circulating email blames copra, and predicts more horses will die from eating this common ingredient in horse-feed preparations.
Tests are being conducted in the wake of the Picton deaths to determine what, if anything, in the feed in question might have caused the fatalities.
Whether copra is to blame has yet to be determined, but the case highlights the potential danger of pretty much all conserved feeds.
By conserved feeds, we mean grains, silage, baleage, copra, and hay, to name but a few.
Copra is coconut meal and is considered an excellent cool-feed for horses, being a good source of oils and protein.
However, like all conserved feeds, there is a risk of contamination by tiny organisms that can release dangerous toxins.
Copra was recently in the news, when dairy giant Fonterra ordered farmers to stop feeding it to milking cows because of the risk of aflatoxins entering the human food chain.
Aflatoxins are a risk to human health, being a known cancer-causing agent, and cannot be destroyed through processing, including pasteurisation.
The dairy giant has told farmers to stop feeding it until a code of practice is in place to ensure that the copra meal supplied to dairy farmers contains fewer than five parts per billion of aflatoxins.
Contamination by aflatoxins usually results from excessive moisture levels at some stage during harvest or storage, causing the growth of moulds that release the toxins.
Excessive moisture at baling can have a similar effect on hay, creating a perfect environment for the growth of dangerous moulds and the toxins they produce.
Again, excess moisture at the time of harvest can encourage the growth of organisms that can contaminate grains with high levels of mycotoxins.
Ensiled grass (silage, haylage or baleage) involves a more complex method of conservation which is affected by sugar levels, acidity, heat, and oxygen levels. However, poor ensiling can encourage multiplication of dangerous organisims, which can result in stock being affected by botulism or listeria poisoning.
The problem for horse owners is knowing whether feed is contaminated. A person with even moderate experience can identify poor hay, silage or baleage.
The problem becomes much harder with grains and the likes of copra, where such quality control will generally have to be left to manufacturers and suppliers.
While horse owners may have some current concerns over copra, the issue is less to do with the copra, which is acknowledged as an excellent feed for horses, and much more to do with ensuring proper harvesting, storage, and transporting, and - just as importantly - testing by suppliers and manufacturers to ensure toxins are not at dangerous levels.