I suggest that you de-worm. Just in case.
The very best way to put weigh on livestock is to feed them the right amount for the weight that you want them to be and to let them gradually get up to that weight.
If you feed a lot of high calorie food, the hen will put on fat, which isn't all that good for her. You want her to build her muscle mass back up and then a small layer of fat. That means a good balanced diet and enough of it and her weight will come up to where it should be.
The very best way to put weigh on livestock is to feed them the right amount for the weight that you want them to be and to let them gradually get up to that weight.
If you feed a lot of high calorie food, the hen will put on fat, which isn't all that good for her. You want her to build her muscle mass back up and then a small layer of fat. That means a good balanced diet and enough of it and her weight will come up to where it should be.