Why does old yeller need to mark his family pigs that year they were born old yeller?

Old Yeller needs to mark the family pigs that year to ensure they can be easily identified and distinguished from other livestock. This is important for preventing mix-ups and protecting the family’s property, especially in a time when wild animals and other dangers pose threats to farm animals. Marking the pigs helps the family keep track of their herd and maintain their livelihood.