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AgVetLink: Number 61, April 2007

Aflatoxins and Animal Feed

In 2006 the dairy National Chemical Contaminants Programme (NCCP) identified raw milk supplies that contained aflatoxin. These levels did not represent a food safety issue but were of interest and some concern as the residues are caused by contaminated feed, and New Zealand milk would normally be free of any trace of aflatoxin. The results are of some concern from a trade perspective as they were close to the limit imposed by the European Union for raw milk at the farm vat.

The findings of the investigations into the levels of aflatoxin in imported copra meal found batches that were elevated and might result in milk at the farm vat failing to meet the requirement of 0.05 µg/kg (micrograms per kilogram or parts per billion) depending upon feed rates. This is the subject of ongoing review by NZFSA. Individual dairy companies are likely to place restriction on the use of copra by suppliers until there are adequate assurances that feed will not cause residues in milk. The same concerns do not exist for meat.

This case serves as a reminder that there is a requirement under the ACVM Act Regulations exempting animal feed that the feed must be fit for purpose, which requires it does not produce residues in primary produce or result in toxic reactions causing pain or distress in animals.

Currently the primary concern is with copra as this material is an ideal substrate for the production of aflatoxins. Other imported feeds such as palm kernel have not been implicated to date.

Storage in New Zealand cannot be ignored with a requirement to keep feeds dry and cool both prior to sale and on farm.

Although there are no formal levels set for aflatoxins in animal feed in New Zealand, levels used internationally are relevant guides. The EU has a limit of 5 µg/kg for lactating dairy cows, which is required to achieve the 0.5 µg/kg in milk. Higher levels can be fed to other classes of stock because there is not the same residue constraint. (Aflatoxins will cause toxicity to animals depending on age and species.)

The following levels used in the US by the FDA are a guide:

• finishing beef cattle – 300 µg/kg

• finishing pigs over 40 kg – 200 µg/kg

• breeding beef cattle, breeding swine, or mature poultry – 100 µg/kg

• immature animals – 20 µg/kg

• animal species or uses not specified above, or when the intended use is not known – 20 µg/kg

The NZ Feed Manufacturers Association is developing a code of practice for animal feeds to address this issue.