Feeding chicks watermelon to cool off, how old should they be?

[JuliePell]

I have pullets and cockerels that range from 9- 12 weeks old.. Its been extremely hot here in Missouri, is it safe at that age for them to have watermelon as a cool down treat? If not safe any suggestions as to what else would work? We do use a fan in the coop alot and we wet down the grass in thier run too.

I just learned - trial and error - that too much watermelon makes them lay soft-shelled eggs. I guess adding grit to their diet would help, or just giving them small quantities. Mine love cucumber, too.