Rockhampton trainer Ricky Vale has pleaded not guilty to four charges of presenting horses to race with prohibited substances in their systems, including cobalt in excess of the prescribed threshold.

Queensland Racing Integrity Commission stewards opened an inquiry on Tuesday but adjourned it to a date to be fixed so Vale could produce evidence in his defence.

Stewards allege the Vale-trained Prince Dan had a positive urine sample to Dexamethasone, a prohibited anti-inflammatory drug, after a race at Rockhampton on February 5, 2016.

Prince Dan also allegedly tested positive to cobalt at Mackay on March 15, 2016, while Reset Our World was alleged to have returned an elevated cobalt level after a race at Rockhampton on March 18, last year.

Another Vale-trained runner Shepiktus allegedly tested positive to high cobalt levels at Rockhampton on March 31 last year.