Export markets are vital to the Australian economy and managing chemical residues is essential to sustaining beneficial trade relationships. Producers exporting meat and edible offal must ensure residues do not exceed the importing country's maximum residue limits (MRLs) as this could jeopardise future trading with that country.
Chemical residue tolerances in food vary between different countries. Some countries have a zero tolerance for certain chemical residues in food while others set MRLs below Australian tolerances. For this reason, recently registered veterinary medicines now have an applicable Export Slaughter Interval (ESI) and producers must submit a National Vendor Declaration (NVD) when selling livestock that requires them to indicate if the animal(s) are still within a withholding period (WHP) or ESI following treatment with a veterinary drug or chemical.
Withholding Periods and Export Slaughter Intervals
Veterinarians are legally required to state the WHP on the dispensing label or inform the producer of the WHP in writing. If there is no WHP, 'Nil Withholding Period' should be stated. This informs the producer of all applicable WHPs so that they can be observed, recorded and communicated to prospective purchasers if animals are still within that period.
Producers also need to be informed of relevant ESIs when treating stock animals with a veterinary chemical. An ESI is the minimum period of time that must elapse between the treatment of livestock and their slaughter for export for human consumption. ESIs are often considerably longer than WHPs, although they may be the same. ESIs are even more important in managing residues than WHPs as the loss of an export market from the detection of unacceptable residues would have dire repercussions for an entire industry.
Veterinarians treating livestock are responsible for informing producers of relevant ESIs and WHPs in writing. It should be remembered when contemplating off-label treatments there may be little or no scientific data available on which to base a WHP or ESI, hence sufficient time must be allowed before animals are slaughtered to ensure there are no residues from treatments. This is particularly important when treating flocks or herds as opposed to individual animals. If it is likely that the treated animals may be slaughtered for export and no ESI is published, advice should be sought from the manufacturer or the APVMA.