4 sources
Gristly Mutton
4 animals yield Gristly Mutton. Each is listed with the regions the compendium records for it.
Legendary Bighorn Ram
Legendary animalsCattail Pond, Grizzlies West, Ambarino
Bighorn (RDR 2)
Mountainous areas
Goat (RDR 2)
Guarma, other sporadic locales
Sheep (RDR 2)
Valentine, Emerald Ranch, Beecher's Hope