What does he do in order to relive these pangs in the call of the wild

Do you mean Buck's hunger pangs? Buck was getting his rations stolen from other dogs:

To remedy this, he ate as fast as they; and, so greatly did hunger compel him, he was not above taking what did not belong to him. He watched and learned. When he saw Pike, one of the new dogs, a clever malingerer and thief, slyly steal a slice of bacon when Perrault's back was turned, he duplicated the performance the following day, getting away with the whole chunk.