Keeping cows healthy and comfortable so they produce safe, high-quality milk requires the tightly controlled use of veterinary medicines and other chemicals on dairy farms.
Veterinary medicines are needed to treat sick cows and prevent disease. Other dairy chemicals such as cleaning agents, herbicides and pesticides, maintain hygienic milk harvesting practices and control pests and weeds.
However, if not managed carefully, product 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 to ensure no risks to food safety are posed by using these chemicals. 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
Some practical tips to avoid veterinary medicine residues accidentally contaminating vat bulk milk include:
- Treated cows are well marked and paint or other markings are topped up regularly.
- All staff understand farm cow treatment identification protocols (should be displayed in the milking area).
- Treatment records are up to date and clearly displayed for milking staff.
- Separating treated cows (the ‘hospital’ herd) from the main milking herd and milking them last.
- Disconnecting the vat hose prior to milking the hospital herd.
- Ensuring test buckets are correctly attached and emptied after individual cows.
- Checking test buckets are large enough to accommodate the highest producing cows.
- Never using medicines off-label (such as increased dose rate, increased treatment frequency or a longer or repeat course) without written prescribing advice from a veterinarian.
- Only products which are registered by the Australian Pesticides and Veterinary Medicines Authority (APVMA) can be used on dairy farms.
- Ensuring dry cows are not able to re-enter the milking herd following dry-off and treatment with a dry cow antibiotic.
- Fostering a culture of ownership and notification among staff regarding medicine mistakes.
- Farm antibiotic residue testing of milk if there is any suspicion of a potential mistake.
Avoid chemical sanitiser residues
All chemical sanitisers used in dairies have been evaluated for safety, and there are ways to ensure traces of them are not left in the pipework of a farm. They include:
- Ensuring milking machines and the vat drain completely after every cleaning.
- Checking and following the label directions of dairy cleaning chemicals.
- Rinsing 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.
- Consulting 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
Maintaining low iodine levels in raw milk is important for the manufacture of infant formula. Milk iodine levels can fluctuate normally due to variation in the iodine levels in a cow's diet. However, it can be 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. But there may be some 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 (there is only one registered in Australia currently) and used according to the label directions. It is critical the product is wiped off, after the recommended teat skin contact time, prior to application of cups to avoid unacceptably high levels of iodine in the milk.