Racing Victoria chief steward Terry Bailey has admitted the rules of racing were not "followed to the letter" in testing for cobalt.

Bailey blamed Victorian lab Racing Analytical Services Ltd for the decision to split urine samples for testing, which he admitted did not "strictly" follow the racing rules.

"That's the way RASL wanted to do it so that's the way we did it," Bailey told trainers Danny O'Brien and Mark Kavanagh's appeal against their cobalt disqualifications.

"Obviously the rules weren't followed to the letter."

After Racing Victoria brought in its cobalt threshold in April 2014, samples were initially sent to Perth-based ChemCentre for testing.

However from June 2014 the urine samples were divided with ChemCentre testing for cobalt and RASL for all other prohibited substances.

Asked who was in charge of ensuring the stewards complied with their obligations under the rules, Bailey said: "At the end of the day the buck stops with the chairman of stewards."

Bailey said he was never told ChemCentre and the Hong Kong Jockey Club lab did not have specific accreditation for the method for testing for cobalt in equine urine.

Kavanagh and O'Brien's barrister Damian Sheales on Tuesday suggested Bailey was lying about what Racing Victoria knew in 2014.

"We say he's untruthful about all matters pertaining to cobalt and what they knew in 2014," Sheales told the Victorian Civil and Administrative Tribunal.

Sheales accused Bailey of telling "a straight-out lie" when the steward maintained he could not remember a drug strategy committee meeting where cobalt was discussed.

"When it's in your interests I suggest to you you're a person who tells lies," Sheales said.

Bailey replied: "You can suggest what you like."

Bailey was also questioned about a media report describing the 2014 spring racing carnival being the cleanest ever, when Sheales said the steward knew about cobalt positives for O'Brien, Kavanagh and fellow trainer Peter Moody.

Bailey said there were only screening results at the time, which were not positive results.

He said Racing Victoria does not notify trainers about positives for any prohibited substance until it gets the first analysis certificate.

"Screening levels we've found in the past have been unreliable.

"We don't act on screens because we're not confident of the readings."

VCAT heard the certificates of analysis relied on by Racing Victoria for one Kavanagh horse and four trained by O'Brien were all dated after ChemCentre had accreditation for its method to test for cobalt in equine urine.

ChemCentre forensic scientist Charles Russo admitted he said should not have put the National Association of Testing Laboratories stamp on certificates before the November 26, 2014, accreditation date.

Bailey continues giving evidence on Wednesday, before Racing Victoria head vet Dr Brian Stewart appears as a witness.

AAP TURF mn/cw