The cobalt hearing involving trainers Mark Kavanagh, Danny O'Brien and vet Tom Brennan, has been adjourned for final submissions after six days of evidence.

The three have been charged over elevated cobalt levels in a horse trained by Kavanagh and four from the O'Brien stable.

Brennan was the primary care vet for the Kavanagh and O'Brien stables and admitted supplying vitamin drips.

He added an extra ingredient to the IV drips, Vitamin Complex, a substance later found to contain large amounts of cobalt.

The two trainers have pleaded not guilty to all charges levelled against them.

Brennan has pleaded guilty to all but one charge of administration to affect the performance of a horse in a race.

The vet said he had been assured there were no prohibited substances in the Vitamin Complex.

The hearing will resume on Friday.

Father and son training partners Lee and Shannon Hope were last month disqualified for three and five years respectively on cobalt charges and are appealing the ruling at the Victorian Civil and Administrative Tribunal.

Peter Moody will front the RAD Board next week on a cobalt charge.