The Ministry for Primary Industries has found no evidence of an animal welfare offence after investigating a complaint about the condition of cows being transported on the Cook Strait ferry.

The animals were photographed whilst being shipped from a farm in the upper South Island to a meat processing plant in Wellington last month.

MPI's Ian Bright says inspectors have interviewed the farmer, the stock agent who arranged the transport, the truck driver, the transport company owner, the yardman at the processing plant and the veterinarian who inspected the animals on arrival.

From this he says there is no evidence of the animal abuse.

Ian Bright adds that's not to say they were in prime condition, but their condition was acceptable for transporting and processing.

Federated Farmers says the investigation into a picture of thin cows that went viral online shows people shouldn't jump to conclusions.

Dairy Chair Andrew Hoggard says the photo did harm the perception of the industry when it didn't need to.

"If you're going to look at those cattle from a different angle, a different situation, they may have looked completely different."

Andrew Hoggard says farmers also need to do all they can to avoid those perceptions being created.