OMG montysmom that's terrible :(
Rice bran and a senior pellet is good for weight gain. And nothing can compare to grazing on fresh grass or 24/7 hay if little pasture is available. A complete supplement is good too. Whatever they are lacking will be replaced by this and it will help everything work properly and allow the body to do the best possible with the food they are getting.
Worming is essential too if you havent done that already