Tag Fattened livestock as a different unit type from unfattened. This allows the “Find all units of unit type” to select only the fattened livestock to gather them together and alleviate the pathing nightmares of livestock economies. And/Or set a rally point from livestock buildings which fattened livestock automatically move to.
Villagers gathering from livestock should continue gathering after going idle and/or when a new fattened animal is in range… regardless of the animal type. (Should not have to manually command separate groups for cows/sheep)
You shouldn’t have to continually tell workers to go back to work. The inefficiency of them standing around idle when there aren’t any animals to work on should be enough.