Not sure what to call it but something like Viktor, Mochi, or Ogdens stuff.
After you unlock the moss blanket, have at least one coop, and complete three trades with him you unlock his thing.
He'll need 20 hens (of any variety) and each 20 you get a roostro, painted or briar hen (a third chance for each to come out) and then after you give him 200 hens he gives you a new type of hen (new breeds). After another 300 he gives you another breed, after another 400 theres a new one. Hens are very common, especially if you specifically go after them. After you give him all of those hens, you get reign of his breeding center/workshop area. A few tabby and hunter slimes wander the area and eat the chickens.
Ideas of new hens: bush hen (sort of like briar/stony mix), large hen (just a bigger hen hen), glass hen (like a mosaic slime/glass pillars in the glass desert), rattle hen (snake pattern), secret hen (like a hunter slime; goes invisible every now and then), pink hen (exactly what you think it is), glow hen (like phosphor slime but without the need of a solar shield and cant fly)