Any person in this state convicted of a crime, who is serving time as a prisoner in the county jail of any county in the State of Oklahoma as a result of said conviction of crime, shall be entitled to receive five (5) days' credit for every four (4) days' time in said county jail provided said prisoner shall have obeyed the rules and regulations promulgated by the sheriff in charge of said county jail in a satisfactory manner. Each prisoner shall also, in addition thereto, be entitled to a deduction of three (3) days for each pint of his blood he donates during his first thirty (30) days of confinement in the county jail, and to five (5) days for each pint of his blood he donates during any sixty-day period thereafter to the American Red Cross or to a hospital approved for such purpose by the sheriff. And the sheriff of said county is hereby authorized to order said credit to be given to said prisoner on the records of the court out of which said conviction is had.