We got 25 day old chicks and have around 15 males (we think). We want to get down to around 9 females and 2 males. (Sadly, our favorite male, Chester, disappeared last week - we think owl as they are in an electrified yard). They will be 13 weeks old and we have read conflicting reports on when to butcher. They are buff orpingtons so they grow slowly. Has anyone had any experience with this?