Even well cared for chickens are very leery about new foods. These poor girls probably had the same food over and over and over- no treats no interaction with humans. I bet if you showed them bugs and worms they would be horrified also. You only need one to try something and then the others will join in. They will come out of their shell and think they are in chicken paradise now that you have them. Just give them time to adjust. The eggs they laid were probably in production before you got them. If they slow up or stop, it is just because of the total change in their life.
You are so nice to take them in
You are so nice to take them in