A Waitomo dairy farmer has been fined $21,739, including veterinarian expenses and costs, for docking the tails of dairy cows.

Peter Anthony William Muller, 65, was sentenced in the Te Kuiti District Court on one charge under the Animal Welfare Act, following a prosecution taken by the Ministry for Primary Industries.

MPI National Manager Animal Welfare & Nait Compliance, Gray Harrison, says Muller deliberately ill-treated the cows by systematically docking their tails, causing unnecessary and unreasonable pain.

"In NZ, docking is prohibited as the tail is a very important and sensitive part of the cow's body. It's used to control flies, but it is also used in social signalling and interactions."

The prosecution relates to an inspection of Muller's Waitomo dairy farm on December 15, 2020. Animal Welfare Inspectors were assisted by a veterinarian.

Of 592 cows inspected they found 534 that had parts of their tails (from above the last 2 to 3 vertebrae) removed by Muller, says a statement from MPI on Tuesday.

It was later established the tails of 64 of the cows had been docked in late July early August 2020 after Muller had been informed by a veterinarian just one month earlier that the docking of cow tails was now fully prohibited and had been since October 1, 2018.

"Where we have clear evidence of offending of this nature, we will take prosecution action," says Mr Harrison.

MPI encourages anyone with information about potential animal welfare offending to use its hotline number 0800 00 83 33.