A variation on the ice-in-the-drinker theme:
At night I've been making sure to put a half-full gallon drinker reservoir in our big freezer. The result in the morning is that the top of the drinker reservoir is one big cube of ice. I fill it up the rest of the way with water, screw on the base, and put it out in the run. It does eventually all melt and warm up, but it seems to help them get through the day pretty well while I'm at work.
At night I've been making sure to put a half-full gallon drinker reservoir in our big freezer. The result in the morning is that the top of the drinker reservoir is one big cube of ice. I fill it up the rest of the way with water, screw on the base, and put it out in the run. It does eventually all melt and warm up, but it seems to help them get through the day pretty well while I'm at work.