Well, tried to make an auto cow cooker and I guess I succeeded.
There's a cow breeder at the top with a 1 block high hole so only babies can go through, which drops them into a holding chamber for them to grow. Every afternoon, lava or crushers will be activated to kill any grown cows depending on whether you want steak raw (trading) or cooked (food). The drops then get sucked into hoppers and into the chest.
Only problem is that changing the state from raw to cooked
while the killing mechanism is on will fuck it up (e.g. lava is on every time except the afternoon, or the lava buckets just pop out of the dispenser), but fixing that will probably make the thing like 2x larger, and I was trying for a more compact cooker.
V1 was a design that had lava on for the whole day and only switched off momentarily for baby cows to fall in without burning up via them activating tripwires, but that didn't work because those little fuckers kept jumping up and down into the lava.
I would take pictures of the wiring, but I spent so much time trying to compact it that I'd probably take another 10 pictures to fully show it, so if anyone's interested, I could send the save file. The cooker is 8x8x8.