Wales will also compete in a new look U18 Six Nations rugby festival, which replaces the home four nations tournament, while selected matches will be played during the Six Nations at U19 level to prepare for the IRB U19 World Championships in Belfast next April. Wales will continue to compete in IRB Sevens tournaments.
WRU High Performance Manager Mostyn Richards said, "Players are now developing at a quicker pace thanks to the WRU Academies and the high performance development structure in place.
"We are constantly being able to call on players who are younger than their age group to represent our international sides and a perfect example of this can be seen in the fact that three of this season's U21 side will be touring Argentina with Wales next month.
"We share the view that there is a strong argument for lowering one age group from U21 to U20 for the Six Nations tournament. Other Unions are in agreement with this change in time for next season's competition."
Assistant Dragons Coach Dai Rees has been appointed as head coach for the U20 side, whilst continuing as Wales Sevens coach, while Justin Burnell and Rowland Philips continue as head coaches of the Wales U19 and Wales U18 set-ups respectively.
Blues head coach Dai Young provided specific scrummaging expertise for the Wales U19 Grand Slam winning side last season, and will follow that group of players into the U20 age group as scrum coach.
WRU national skills coach Robin McBryde will carry out the same role with the U18 coaching team while fellow WRU national skills coach Wayne Jones joins the U20 management as assistant coach alongside Pontypridd's Simon King. A new face to the international age grade scene is Neath assistant coach Patrick Horgan who will assist Justin Burnell within the U19 set-up alongside another WRU national skills coach, Gruff Rees.
Richards continued, "All of these appointments are potential professional coaches of the future. That is an ideal environment both for the potential professional players, and for our upcoming coaches in Wales."
WRU Elite Coach Manager Leighton Morgan added: "There is no doubt that the quality and ambition of this group of individuals is very promising and exciting indeed. All the coaches selected for the 2006/07 season are either Level Four qualified, due to qualify this summer or will enter the programme when the fourth cohort begin their studies in September 2006. The four managers have also gained the same qualification or equivalent."
The changes have signalled an end to Chris Davey's reign as Wales U21 head coach. Davey steered Wales to three U21 Grand Slams and a further Six Nations Championship title in his nine years at the helm. Mostyn Richards paid tribute to his contribution to the Welsh cause: "Chris, along with Wales U21 team manager Wayne Hall have been magnificent ambassadors for the WRU. The pair have given sterling service to the Union and their success at U21 level is unparalleled within the northern hemisphere.
"I would also like to pay tribute to Cledwyn Edwards who has decided to stand down as manager of the U19, after nearly 20 years service to international age grade rugby at U19 level and for Wales Youth."
Chris Davey said, "Obviously, I was very disappointed to hear that I would no longer be involved in the Wales age grade set-up. The last nine years has been a fantastic experience which has allowed me to work with some excellent players and a superb management team.
"The decision to re-shape age grade rugby sees the end of Wales U21 which is disappointing from a personal point of view. I would like to thank everyone I have worked with in my time as coach to Wales U21, it's been an absolute pleasure."
Davey will take charge of his last tournament at the IRB U21 World Championship in France which begins on June 9.
WRU National Coaching Appointments
Head Coach Dai Rees
Assistant Coaches Simon King and Wayne Jones
Scrum Coach Dai Young
Team Manager Nick Rose
Head Coach Justin Burnell
Assistant Coaches Patrick Horgan and Gruff Rees
Scrum Coach Wayne Jones
Team Manager Darryl Hill
Head Coach Rowland Phillips
Assistant Coaches Gethin Watts and Nicky Lloyd
Scrum Coach Robin McBryde
Team Manager Terry Cobner
Head Coach Dai Rees
Assistant Coach Gareth Baber
Team Manager Col David Jenkins