I was wrong in saying that the original T&B rules sheet mention the pig herd. I confused the rules with rules of Count, King and Robber. Sorry about that.
However, CAR only says that pig and pig herd can be score independently. It's an interpretation of the rule if you say it is always scored. Note #178 in CAR 7.3 suggests that it should always be scored BUT it is a house rule (house icon and blue font).