Moved 3 barns, whole food chain collapsing, slaughtering is out of balance, herds sick and diminishing, storage goods are not moved with the building, milking setting not kept. Nice disaster it is.
Slaughter button allows you to slaughter any number of your cows from that barn. As mentioned elsewhere, it is not immediate. Depends on what your herders are doing at the time.
Earlier it was stated, that with enough food and happy people a town would grow faster, I do not see that at all, as stated before the upward spiral is really out of balance with the cascades that can happen in a city. Especially on higher difficulty levels.
The next part of the downward circle, because of the lack of town growth, is your maintenance shortages.
But a condemned Barn, with cows in the herd, is funny and it feels strange you cannot prioritize repairs. Also you cannot prioritize maintenance above new buildings / upgrades, only by blocking each of those separately. Also it is not possible to prioritize within the building queue itself.
I haven’t had that type of disaster yet. If I did, I would clear wide swaths of buildings to eliminate them and consolidate my town back to its base, then start rebuilding again. You have a HUGE imbalance in your villagers attached to food, compared to builders and laborers. I can feed 150 people with 3 7x7 fields, foragers, and hunters.