Leading country NSW jockey Greg Ryan has lost his fight to overturn a lengthy riding suspension.

Racing NSW stewards gave Ryan a six-week ban for his ride on Grey Pariz in a race at Dubbo in June and the Appeal Panel of Racing NSW dismissed his appeal against the suspension.

Ryan was found guilty under an Australian racing rule which deals with a rider giving his mount every chance to finish in the best possible placing in a race.

Ryan's appeal against the severity of the ban has also been dismissed.

Grey Pariz had shown natural speed to lead in three starts but settled at the tail of the field at Dubbo before finishing third - a length from the winner - as the $2.50 favourite.

Ryan, who has been riding on a stay of proceedings, will start his suspension on Tuesday.

He can resume riding on September 16.

Ryan finished the 2013-2014 racing season with 154-1/2 winners to finish runner-up to Victoria's Brad Rawiller in the national jockeys' premiership.

His appeal was heard on Tuesday with the findings handed down on Friday.