HALF A dozen out-of-contract ruckmen are attracting interest from AFL clubs looking to bolster their ruck stocks at season's end.

The six players opposition clubs are hoping to entice into the annual rucking revolving door are Jarrod Witts (Collingwood), Nathan Vardy (Geelong), Zac Clarke (Fremantle), Majak Daw (North Melbourne), Tom Downie (GWS), and Tom Nicholls (Gold Coast).

Witts has been linked with the Brisbane Lions, while Vardy has reportedly attracted interest from the Western Bulldogs.

Both players have been starved of opportunities after being touted as potential stars after just a few games.

Witts attracted interest from the Giants at the end of last season but decided to stay with the Magpies, however he has only played two senior games this season after a finger injury ruined the first half of the season.

The 23-year-old could attract a second-round draft pick if he was traded, with Brodie Grundy's stronghold on the senior ruck spot and the emergence of Mason Cox limiting his chances at the Magpies.

Vardy has played 25 games since making his debut in 2011. A hip injury and a knee reconstruction have made life difficult for the 25-year-old.

He has played just one AFL game this season, but been fit enough to play nine VFL games and appears to have slipped behind Mitch Clark in the pecking order.

At his best, Vardy is an exciting ruck-forward.

Fremantle's athletic free agent Zac Clarke will attract interest from Victorian clubs, while North Melbourne is keen to retain Majak Daw but he will be in demand if he chooses to explore options elsewhere.

Downie has been in excellent form in the NEAFL for the Giants and is a solid back-up for Shane Mumford.

Carlton and Richmond are understood to have been among several clubs monitoring the 23-year-old, who has played nine games for the Giants since his debut in 2013, which was against the Tigers.

He is understood to remain a required player for the Giants, which recruited him in the 2011 NAB AFL Draft.

Another required ruckman yet to sign is Gold Coast's Tom Nicholls, although parties are understood to have been having positive discussions about his future.

Nicholls battled to cement his position as No.1 ruck early in the season after the club cleared Zac Smith to Geelong, but he has returned to good form in recent weeks.

Geelong is one of the few clubs with more than one top quality ruckman on its list, with Richmond, the Brisbane Lions, Carlton, North Melbourne and Melbourne understood to be in the market for at least a back-up ruckman.

At the end of 2015, seven ruckmen changed clubs, with Smith leaving the Suns for Geelong (14 games in 2016), ex-Lion Matthew Leuenberger heading to Essendon (13 games), former Eagle Callum Sinclair crossing to the Sydney Swans (13), Andrew Phillips leaving GWS for Carlton (eight), former Roo Daniel Currie heading north to Gold Coast (four), journeyman Jonathan Giles joining West Coast after a stint at Essendon (one), and ex-Cat Dawson Simpson joining the Giants (no games).

Hawthorn's 2008 premiership team was the most recent flag-winning combination to not have at least one ruckman recruited from another club.