Training partners Lance O'Sullivan and Andrew Scott have been fined $50,000 and ordered to pay costs in New Zealand's first cobalt case.

They pleaded guilty to presenting three horses to race with illegal levels of cobalt in their systems which they said must have occurred because the horses and dairy cattle on O'Sullivan's farm were sharing troughs which had cobalt added to the water.

Judicial Control Authority chairman Professor Geoff Hall said they had not been influenced by the Peter Moody case in Australia where the leading trainer has been banned for six months, prompting his retirement from the sport.

"We have had to decide this case on the facts presented to us," Hall said.

"Significantly, the Racing Integrity Unit has not sought the imposition of a penalty of disqualification or suspension.

"We believe the mere fact that this case has resulted in admitted breaches, and what we consider to be a significant financial penalty, will be a very salutary lesson to the respondents."

The cobalt threshold in New Zealand is 200 micrograms per litre of urine and the three runners from the O'Sullivan and Scott stable to return excessive levels were Quintastics (640), Sound Proposition (541) and Suffire (309).

The judgment said while counsel for the RIU argued the investigative body could not be satisfied the levels came from the cattle supplement, it also said it could not discount the possibility.

"We emphasise that we accept the explanation provided by the respondents as to the cause of the elevated cobalt readings," the JCA said.