Beekissed
Mountain Sage
Losing animals is always difficult, but it helps me to think of it in terms of culling for more resilient stock. Do you really want to have a herd based on animals that barely tolerate living conditions?
I lean towards this way of thinking also. Though it's hard to lose stock, it's also a starting point for changing things in how you do so and what kind of stock you want to raise.
In the summer we moved our meat rabbits out to an open air situation and established fans, gave them frozen water bottles to lie on, provided shade and didn't breed them during the summer months, much like everyone else describes.
If I had to do rabbits all over again, I'd be raising them in tractors and moving them to fresh graze a few times a day, but I think I'd also provide them a den situation during the hottest months. A wild rabbit will den up during the heat of the day and come out to feed at night, so being able to provide that situation for rabbits would be my goal.