"After missing and being late for some practice assignments, Johnny explained that he had been feeling ill. Consequently, we agreed that it was in everyone's best interest for him to go home a day early," said a statement emailed Sunday by camp spokesman Greg Blackwell.
The camp is run by Saints quarterback Archie Manning and his two NFL QB sons, the Broncos' Peyton and the Giants' Eli.
The Texas A&M quarterback is the only freshman to win the Heisman Trophy. The school had no comment beyond the camp's statement, a university spokesman said.
The camp, held at Nicholls State in Thibodaux, began Thursday and ended Sunday.
The Mannings' statement did not say which assignments Manziel missed.
He was absent from a Saturday evening exhibition by college and pro quarterbacks and wide receivers, The Daily Comet reported Sunday (http://bit.ly/15FYpm0 ). The audience pays $12 to $15 a person to see the exhibition and to support the university's athletic department.