Antibiotic Residue and Aflatoxin M1 Tests in Milk

An antibiotic residue test looks for traces of medicine in milk, and an aflatoxin M1 test looks for a toxin that comes from mould in animal feed. Dairies often ask for both, together with a bacterial count, to judge the quality of milk. A farmer can use the same tests to check his own milk before it is sold.

What is an antibiotic residue?

When a cow or buffalo is treated with an antibiotic, some of the medicine can pass into her milk for a time. The traces left in the milk are called residues. They matter for several reasons. They can upset the culture used to make curd and cheese, they can cause reactions in people who are sensitive, and widespread low-level exposure is a concern for the spread of resistant germs. For these reasons, dairies check incoming milk. The Milk Antibiotic Residue Test looks for these traces. The lab report says whether residues were found with that test, and the lab quotes no limits.

How long milk should be kept out after treatment is a question for your vet, who knows the product that was used. Do not guess. Tell the lab and the dairy if an animal was treated recently.

What is aflatoxin M1?

Aflatoxins are poisons made by some moulds that grow on grain, groundnut cake, cottonseed and other feed that has been stored damp or too long. When a cow eats contaminated feed, her body turns part of the toxin into a form called aflatoxin M1, and it appears in her milk. Heating the milk does not remove it. The Milk Aflatoxin M1 Test looks for this toxin in a milk sample. A positive result points to a feed problem, which your vet or nutritionist can help trace, and it is a reason to check the stored feed and fodder.

Why does the bacterial count matter?

The Milk Total Bacterial Count (TBC / Standard Plate Count) estimates how many bacteria are in the milk. A high count usually means dirty equipment, dirty hands, warm storage or a slow journey to the chilling centre, and it makes milk go off sooner. It is a measure of hygiene and handling. It does not show whether a particular animal has mastitis, which needs its own udder tests.

How should a clean sample be collected?

Careful sampling decides how useful the result is.

1. Wash and dry your hands, and clean the teats.
2. Discard the first few streams of milk.
3. Collect into a clean, dry, lidded container that has never held anything else, without touching the inside of the lid.
4. Label it with the animal or herd, the date and time, and note any recent treatment.
5. Keep it cool and send it quickly.

For a sample of the whole herd's milk, mix it well first. A different container is needed for each test only if the lab says so. Ask when you book.

Who should test and when?

Dairies and cooperatives test incoming milk. Farmers who sell directly can test before delivery, especially after treating an animal or when a feed batch has been stored for a long time. The Milk Quality & Adulteration Pack groups these checks with composition, adulteration and cell count tests. Results are for your information and do not replace official food-safety testing.

What should you do with the result?

Talk it over with your vet. A registered veterinarian can connect a residue result to the treatment records and an aflatoxin result to the feed, and can tell you what to check next.

Read next

If a cow's milk or her calf's health is the worry, see Calf Health in the First Weeks: Colostrum and Lab Tests. For breeding herds, read Bull Semen Evaluation for Better Breeding Results.

Testing in Bhopal

The lab at C-200, C Sector, Shahpura, Bhopal accepts milk samples, and collection is free anywhere in Bhopal. Call or WhatsApp +91 88175 01118 so the lab can confirm the method, sample needs and reporting time when you book. Farms in other districts can send chilled samples by courier or through their vet.