I think it'd be cool if there was an ability to have Zombies, Zombie variants and/or other mobs, when not already targeting a player, villager, or iron golem, attack animals (chickens, pigs, cows, horses, mooshrooms, etc). It'd require the player to actively protect their livestock and stable and make zombies a more active threat, since they'd be frequently mobile.

You can do this yourself with the targetAttacker feature.

Thanks for the tip!