A WARRNAMBOOL stock agent has been fined $2000 for selling a calf containing high antibacterial chemical residues.

Stock agent Blair O'Toole pleaded guilty in the Warrnambool Magistrates Court last week to several charges relating to the detection of antibacterial residues in a calf carcase that exceeded national maximum residue limits.

The chemical level detected in the calf for the product used was 360 times the maximum permitted residue limit (MRL) for the drug Sulphadimidine, 300 times the MRL for Sulphadiazine and also above the MRL for Streptomycin.

Magistrate Jonathan Klestadt fined Mr O'Toole $2000 without conviction.

The threat to damage  trade reputation or loss of a major export trade from such a high level detection of drugs in a food product was disturbing, Mr Klestadt said.

Mr O'Toole had maintained he did not know the calf was within the withholding period for the chemical and that he made reasonable inquiries about the calf's treatment status.

Koroit calf rearer Julie Gaskin pleaded guilty to charges relating to the dispatch, sale and treatment of the calf without adequately recording or advising the animal had been treated with a veterinary product.

She was fined $650 without conviction.

Department of Primary Industries senior prosecutor Geoff Morsby, told the court Mr O'Toole had despatched, sold and delivered a Friesian bull calf to a Warrnambool abattoir in May 2011 without notifying the buyer in writing that the calf was still within a withholding period for an antibacterial chemical treatment.

The calf had been treated for scours on the Koroit property of Ms Gaskin two days before it was transported to the abattoir by Mr O'Toole, but an accompanying national vendor declaration form indicated the calf had not been treated within the withholding period of two weeks.

Department of Primary Industries regional animal health officer Leon Watt said livestock sold exceeding maximum chemical residue limits threatened access to Australia's major export markets. These markets were underpinned by stringent chemical residue requirements.

"Livestock producers needed to ensure that any animals made available for slaughter comply with withholding periods and export slaughter intervals.

"This is underpinned by maintaining the required chemical use records, including documenting details such as product trade name, species, identification numbers, location of animals and dates of first and subsequent treatments."

He said in the case before the Warrnambool court last week, there were no chemical records maintained and no way of determining which calf had been treated and when.

"Withholding periods are legally binding and are printed on chemical-drug labels."