IF your chickens touch the ground...as has been explained by Dawg53...they risk the issue of having worms...DE does NOT get rid of worms...worms will kill a chicken if they are infested with them..fact.
Safeguard seems to be the best product recommended here on BYC for treating a worm infestation....IF you ever see worms in the poop of a chicken it is heavily infested with them. It is prudent to treat the flock every 3 - 6 months with a de-wormer depending upon your soil conditions. All eggs must be dispensed of during the treatment period...after the initial dose you should re-treat in 14 days...so eggs must be dispensed of for 28 days in total.
I have just de-wormed my chickens...after three days, they are laying more eggs than they have done in the past month...my dogs enjoy eating the eggs but they are not fit for human consumption..my chickens look great...try it please..the rewards are great for the chickens!