Spirit of Tasmania ferry operator TT-Line has appealed a court ruling that found them guilty of animal welfare law breaches over the deaths of 16 polo ponies.
The horses, which travelled in a converted shipping container, died during a voyage across Bass Strait from Devonport in Tasmania to Melbourne on the night of January 28, 2018.
In October, TT-Line was found guilty of 29 criminal offences after a lengthy hearing in Burnie Magistrates Court.
Magistrate Leanne Topfer ruled the company failed to ensure the ponies were individually stalled, as per requirements, or ensure they had adequate ventilation.
She also ruled TT-Line relied solely on a declaration from former Australian polo captain Andrew Williams, who was involved in the horses' transportation, that ventilation was adequate.
TT-Line has appealed the ruling in the Supreme Court of Tasmania.
According to a court document, it argues there were errors in law and Ms Topfer didn't afford the company procedural fairness.
"The evidence ... did not establish, beyond reasonable doubt, that the double stalling of the animals was reasonably likely to result in unreasonable and unjustifiable pain or suffering to the animals," the document reads.
The matter is set to appear before the Supreme Court of Tasmania in February.
TT-Line remains listed to be sentenced for the breaches in Burnie Magistrates Court on December 21.
Ms Topfer said the voyage was on a "warm evening where there was a clearly inadequately ventilated transport unit stationary for 10 hours".
There were too many horses in the unit and 16 horses were exposed to the risk of acute heat stress and asphyxiation and died from respiratory failure, she said.
TT-Line had earlier pleaded not guilty to one charge of using a method of management reasonably likely to result in unreasonable and unjustifiable pain and suffering.
It had also pleaded not guilty to 28 counts of failing to ensure a horse was individually stalled.
The guilty ruling prompted TT-Line to suspended the transportation of livestock on the Spirit of Tasmania for several days.
