So long as cattle live outdoors, they will rub on fences, be bitten by bugs and wrinkle in their leg pits. Range marks, branding marks, color variations and texture variation are normal and intrinsic to leather.
I love to feature these natural marks and I suggest we feature our own range marks as well. Let the water stains and pen marks be, let the sun spots and oil prints be, let them build up as patina. Leather can last hundreds of years with good care and conditioning. Let yourself be part of the story of the piece.