* Broad claims 300th test wicket with third ball of innings
* Rogers, Smith, Warner, Marsh, Voges, Clarke fall in first 40 minutes
* Australia in huge trouble after being put in to bat (Adds details)
By Ed Osmond
NOTTINGHAM, England, Aug 6 (Reuters) - A rampant Stuart Broad took five wickets as England reduced shell-shocked Australia to 29 for six in an extraordinary start to the fourth Ashes test at Trent Bridge on Thursday.
Broad struck five times in his first four overs, claiming his 300th test victim with the third ball of the morning when he had opener Chris Rogers caught at first slip by captain Alastair Cook for a duck.
Steven Smith, on six, edged the last ball of the first over to Joe Root in the slips and David Warner nicked his second delivery from Mark Wood to wicketkeeper Jos Buttler, leaving the touring side in tatters at 10-3.
Australia captain Michael Clarke, who dropped one place down the order to number five, walked out to face the ninth delivery of the match.
England, who won the toss and lead the series 2-1, struck another blow when Shaun Marsh edged Broad to Ian Bell at second slip and Adam Voges was brilliantly caught one-handed by a diving Ben Stokes at gully as Australia slumped to 21 for five.
It was the first time in test history that the first five wickets of the match had fallen within 25 balls of the start.
Clarke survived 25 minutes for his 10 runs before he drove loosely at a wide ball from Broad and was well caught above his head by Cook.
It was Broad's 14th five-wicket haul in a test innings and was the first time an England bowler had taken five wickets before lunch on the first day of a test since Sydney Barnes, against South Africa in 1913.
Broad, playing his 83rd test, became the fifth England bowler to take 300 test wickets after fellow pacemen James Anderson, Ian Botham, Bob Willis and Fred Trueman.
Anderson, who tops the list with 413 victims, is missing the fourth test due to a side injury he sustained in the last match in Birmingham. (Editing by John O'Brien)