Thanks for the replies guys!

The one female who's been paired since October has been hit and miss with eating (off feed for 2 months, on feed for 2 months) but stopped first part of April. The other is so hit and miss with food I can't base anything on that! I've got one male that I've been using since January and I'll probably pull him end of the month. I've got another that we are trying to convince to breed (he's young) so he'll go a lot longer. I'm trying not to give up on them! Both look miserable.