I don’t know the cause beyond “It sometimes happens when hay spoils,” but I was trying to investigate how different fodder qualities (and whether clover on poor fodder works well) … and after getting a very nice baseline, I started seeing fodder consumption thrash wildly. My test town produces no root vegetables or grains, so we can be confident that all the animal fodder for the one barn is coming from hay.
Here’s the baseline, with several years on good fodder with clover, and then two years on 21% fodder:
(I failed to screenshot it while it was on the low fodder quality, but the graph is useful, at least.)
But then, I moved to clover on ~30% base fodder, and this happened, and it probably wasn’t because of the poor base fodder:
Not even switching back to the broadly good field solved it, at least not right away.
I had had the Eternal Ice of Amatok as a relic, and when I removed that, things stabilized back to my original baseline, but it’s possible that it was because of the clover on a bad field, because the last two years here are when I switched back:
On the other hand, there’s also a bunch of hay spoilage again.
My final screenshot here is when I had the cows instead going to the empty (no farm, only 83% quality fodder) pasture off the bottom of the screenshot, and this is why it looks like the problem is hay spoilage:
That last year is from the 83% fodder field, and, as far as I can tell, the cows really did only eat 18 hay all winter, which is bonkers. Usually, they ate 360!
Here’s my test rig save, in case you don’t have one handy. You might be able to replay that winter from the autosaves, too:https://drive.google.com/file/d/1Zzs7aWx5shkMDwDXPQ8mPkAv6N_XFEqC/view?usp=drive_link