Greens senator Mehreen Farqui's motion calling for an inquiry came in response to footage of retired racehorses being mistreated before slaughtered at an abattoir was broadcast by the ABC last month.

The vote was far from a photo finish, with the motion comprehensively beaten 45 votes to 10.

The nine Greens senators' only supporter was Centre Alliance's Rex Patrick.

Government minister Johnathon Duniam said animal welfare and horseracing regulation were matters for state and territory governments.

"This story was, of course, confronting," he told parliament.

The Queensland government has established an inquiry into the abattoir featured in the ABC report and the treatment of retired racehorses.

Senator Duniam said the federal government was investigating alleged animal cruelty at the abattoir because it was registered, while agriculture ministers were weighing up a national horse register.

"What can be done by the Commonwealth is already being done," he said.

Labor frontbencher Katy Gallagher said the images and evidence were appalling, but it was important to let inquiries run their course.

"We're deeply concerned animal welfare failings have happened with retired racehorses, however, there are a number of investigations and reviews underway," she said.

Senator Faruqi last week urged people to boycott the Melbourne Cup, Australia's most famous race.

Australian Associated Press