Feeding rescue hens properly in the first few weeks makes a huge difference to how they adjust. Before they were rescued, the hens will have been fed on layers pellets or layers mash and possibly never ate anything different.
We have a general article on feeding hens on what chickens like to eat which you have a read of also, but this article contains specific advice on feeding battery or rescue hens.
It may seem kind to give the hens treats, but the stress and shock of being moved is a lot for the hen to deal with. In the first couple of weeks, I recommend to not feed your rescue hens grains, fruit and vegetables or any other treats.
After that, you can slowly introduce some grains. You can gradually also introduce some green vegetables into their diet if you wish.
It is also a very good idea to give rescue hens grit, this is available from our online shop. Oyster shell grit is soluble and contains calcium which will help to strengthen the hens bones and also ensure that the egg shells are good and strong.
Your newly rescued hens will also need to have clean, fresh drinking water during waking hours.