I've no option other than keeping them on wid/hens perches and they do pair,I exercise them daily and feed them less than 1oz a day but get the odd few that pair.I have to lock one of the pair in a darkened box and alternate this daily with the other hen,then as I take the hen out of the box I put it in with it's cock for a couple of minutes.It's a pain but as I race these hens it is a big problem if they pair again when it comes to racing.