Australia's Vow and Declare wins Melbourne Cup thriller

Australian stayer Vow and Declare won the 159th running of the Melbourne Cup by a neck at Flemington racecourse on Tuesday, holding firm in a thrilling sprint to the line.

The Danny O'Brien-trained gelding worked hard to win the gruelling 3,200-metre handicap, dubbed "the race that stops the nation", and gave jockey Craig Williams his first Melbourne Cup triumph.

Runner-up Master of Reality, ridden by Frankie Dettori, looked to have it won at the 100-metre mark but Vow and Declare made a last desperate kick to seal the $5.52 million race with Prince of Arran third in a photo finish.

"It's an amazing win, a special thing to happen," said O'Brien.

"I really can't believe it, I just feel incredibly blessed to have a horse good enough to be in it.

"The last 100 (metres) he just wouldn't give in."

While a festive public holiday crowd soaked up the spring sunshine, the Cup ran amid a heated debate about animal welfare following an investigative report into the mistreatment of retired racehorses and the alleged slaughter of hundreds of thoroughbreds at local abattoirs.

'Nup to the Cup!'

Animal rights advocates demonstrated outside the gates at Flemington, chanting "Nup to the Cup!" and demanding an end to the race. 

While slaughtering horses instead of rehoming is not illegal in Australia, an undercover probe by the Australian Broadcasting Corporation alleged the practice was far more widespread than acknowledged.

It detailed healthy horses being brutalised at one abattoir before being killed on an "industrial scale", with their meat shipped overseas for human and pet consumption.

It sent shockwaves through the industry and revulsion among some fans, with the industry pledging to do better.

While the Melbourne Cup was not directly linked to those slaughterhouses, the race was already a target of animal rights activists after six deaths since 2013, although there were no reports of injuries Tuesday.

Despite this, fans appeared undeterred. No attendance figures were immediately available — 90,000 were expected — but the grandstands were heaving.

And despite pressures to boycott the race, betting agency TAB was cited in local media as saying they expected more than three million people would have a flutter on Tuesday.

First staged in 1861, the Melbourne Cup has been run on the first Tuesday of November since 1876, and the winning horse instantly becomes a household name in Australia.

It is a cultural institution and tens of thousands of well-dressed punters flock to Flemington, with boozy parties held nationwide.