Northampton manager Chris Wilder has confirmed interest from Premier League and Championship clubs for Ivan Toney.
Notts County full-back Jordan Cranston has left the club by mutual consent.
Michael Keane, a 20-year-old centre-back, has joined Derby and will remain with the Rams until January 2.
Striker Will Keane has joined Wigan on loan until January 1 and the pair could come face to face at the DW Stadium on Sunday when the Latics take on Derby in a Championship fixture.
England Under-21 international Michael Keane has made three Capital One Cup appearances for United and also had a loan spell with Leicester City last season.
United have now allowed him to leave the club again on an initial short-term basis to enable him to gain further experience.
Keane will link up with former Old Trafford coach Steve McClaren at Derby who have won a battle with several other Championship clubs for his services.
Will Keane, who trained with the England Under-21 squad earlier this month, has made one senior appearance for United as a substitute in the 3-2 home defeat to Blackburn back on December 31 2011.
He missed last season with a cruciate knee ligament injury suffered while playing for England's Under-19 side and is making his first loan switch.
Meanwhile, United have allowed Welsh forward Tom Lawrence to join Carlisle United on loan with the move running until January 4.
There has also been further loan movement at Derby with striker Callum Ball moving to Notts County on loan until January 2.