xkcd

If Dairy Farmers of Canada allowed half of what American dairy allows on their farms, I would reject them at the farm level tomorrow.

Shit, I had a positive bacterial test at a production facility. Half of the trailer was contaminated and threw a positive. It's so rare QA at that plant didn't know what to do. Multiple tests, a rejected half tank, and after finding out... A small farm of about 2000L accidentally milked one cow on antibiotics. They milk 4-5 times between farm pickup days. So one cow, one time, over 4-5 herd milking, for around 2000L of milk, was enough to flag an antibiotics test of nearly 16000 litres of milk in half of a tanker. That single cow may have produced 8-13 litres of milk in that 2000L pickup, which was enough to flag a test on 16000L.

For comparison sake, American milk allows antibiotics in their milk. They can milk cows on antibiotics and keep them in the main herd.