Farmers could be surprised by news it is looking less likely Mycoplasma bovis will be able to eradicated easily.

Eleven-thousand cows have been put down so far, and that figure's set to double by the end of the month.

Federated Farmers dairy industry chair Chris Lewis told Kate Hawkesby at the beginning, they believed bovis could be contained, but over the past month, that's looked a lot less possible.

"We test herds, we can test animals but it's not giving us one hundred percent results until the animal is slaughtered."

LISTEN ABOVE AS CHRIS LEWIS TALKS TO KATE HAWKESBY