DALLAS — Former Dallas Cowboys tackle Josh Brent, who was released from jail Sunday, will spend at least 45 days in rehab for substance abuse.State District Judge Robert Burns agreed Friday to modify Brent’s jail sentence to allow him to enter a residential facility for substance abuse treatment. Burns’ order was made public Monday.Burns ordered Brent to report immediately to rehab and remain there for 45 days. Brent was convicted in January of intoxication manslaughter in the December 2012 death of Jerry Brown, a Cowboys practice squad linebacker and college teammate. He was given 10 years’ probation, including 180 days in jail. Brent has retired from the NFL but could seek to play again.