ORCHARD PARK, N.Y. — Veteran linebacker Manny Lawson was cut by the Buffalo Bills on Friday in a move that further depletes their pass-rushing depth.

Fullback Jerome Felton was also among the 21 players released by the Bills in moves made a day before NFL teams are required to establish their 53-player rosters.

Lawson’s release comes as a surprise because the 10-year NFL veteran was projected to start in place of injured rookie first-round pick Shaq Lawson. Manny Lawson, however, opened training camp sidelined by a partially torn pectoral muscle and wasn’t cleared for practice until three weeks ago.

He is also being investigated by the NFL for potentially violating the league’s personal conduct policy. Lawson said he’s done nothing wrong, and the NFL has not revealed what it is investigating.

Coach Rex Ryan previously spoke highly of Lawson, citing the player’s versatility and intelligence. Ryan is scheduled to discuss the moves before the Bills practice later in the day.

The linebacker position has been in flux for the past month. Shaq Lawson will miss at least the first six games of the season recuperating from shoulder surgery, and rookie second-round pick Reggie Ragland sustained a season-ending left knee injury last month.

Veteran free-agent addition Lorenzo Alexander is expected to take over the starting spot in place of Lawson. Buffalo also addressed its linebacker and special teams depth this week by acquiring Lerentee McCray in a trade with Green Bay and signing Ramon Humber, who both remain on the roster.

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The Bills also cut linebackers Kroy Biermann and Randell Johnson.

Felton was cut after he struggled to establish a role in his first season after signing a four-year contract with Buffalo last year.

The Bills instead are going with youth at fullback with rookie free-agent addition Glenn Gronkowski — the younger brother of New England star tight end Rob Gronkowski — remaining on the roster.

Buffalo now has a 54-player roster, including defensive tackle Marcell Dareus, who will miss the first four games of the season serving an NFL suspension for violating the league’s substance abuse policy.

Receivers Walter Powell and Greg Salas secured the final two spots behind Sammy Watkins, Robert Woods and Marquise Goodwin.

Receivers not making the cut were Jarrett Boykin, Dez Lewis and Kain Colter. At Northwestern, Colter shared quarterbacking duties with Trevor Siemian, now the Super Bowl champion Broncos’ starter.

Also released were cornerbacks Mario Butler, Sterling Moore and Sammy Seamster, running backs Boom Herron and James Wilder Jr., and tight end Blake Annen.

Offensive linemen released were Marquis Lucas, Chris Martin, Cyril Richardson and Fernando Velasco. Defensive linemen released were Brandon Deaderick, Lavar Edwards, Max Valles and Casey Walker.