Avoiding Residues
Keeping cows healthy so they produce safe, high-quality milk requires the appropriate use of veterinary medicines and other chemicals on dairy farms.
Farm requirements
Veterinary medicines are needed to treat sick cows and to prevent disease. Other dairy chemicals such as cleaning agents, herbicides, and pesticides, maintain hygienic milk harvesting practices and control pests and weeds.
However, if products are not managed carefully, residues can pose risks to market access and the dairy industry's reputation. All dairy farmers supplying milk for human consumption are required to have an approved food safety program in place. In addition, milk processors implement routine antibiotic testing of raw milk and dairy products, to ensure these antimicrobial compounds do not enter the food chain.
The Australian Milk Residue Analysis (AMRA) Survey is a national, independent program which monitors on-farm chemical residues in bovine milk.
Avoid veterinary medicine residues
To avoid veterinary medicine residues accidentally contaminate the bulk milk vat, ensure that:
- Treated cows are well marked and paint or other markings are topped up regularly.
- All staff understand the farm’s treatment identification protocols .
- Treatment records are up to date and clearly displayed for milking staff.
- Treated cows (the ‘hospital’ herd) are separated from the main milking herd and milked last.
- The vat hose is disconnected prior to milking the hospital herd.
- Test buckets are correctly attached and emptied after individual cows.
- Test buckets are large enough to accommodate the highest producing cows.
- Medicines are never used off-label (such as increased dose rate, increased treatment frequency or a longer or repeat course) without written prescribing advice from a veterinarian.
- Dry cows are not able to re-enter the milking herd following dry-off and treatment with a dry cow antibiotic.
- Milk samples are sent for antibiotic residue testing if there is any suspicion of a potential mistake.
Avoid chemical sanitiser residues
All chemical sanitisers used in dairies have been evaluated for safety. To ensure traces of them are not left in the pipework of a farm:
- Ensure milking machines and the vat drain completely after every cleaning.
- Check and follow the label directions of dairy cleaning chemicals.
- Rinse chemical sanitisers from the plant immediately after use, or preferably immediately prior to the next milking. Warm or cold water should be used at the same volume as used for the sanitising rinse.
- Consult with a dairy chemical specialist to choose cleaning products that have a low risk of residues.
For information on how to prevent residues when cleaning milking machines and bulk milk vats, see Avoiding Residues Resources below.
Avoid iodine residues
Ensuring low iodine levels in raw milk is important for the manufacture of infant formula. Milk iodine levels fluctuate normally due to variation in the iodine in a cow's diet. However, it is difficult to maintain acceptably low levels of milk iodine when iodine-based pre-milking teat disinfection is being used.
There is currently little evidence to support the use of pre-milking teat disinfection in pasture-based dairy herds, although there may be a benefit in more intensive systems or during times of high environmental mastitis challenge.
If pre-milking teat disinfection is to be used, it must be with a product registered for this purpose and used according to the label directions. It is critical the product is wiped off prior to application of cups to avoid unacceptably high levels of iodine in the milk.
