Ok because I know it's hard, I'll help out. If you don't have nameless venom or just don't want to get or use it. There are 3 ways of raising them without it.

1st. Is obvious just use a pig to heal them, but he will require A Lot of food.

2nd. Is use a snow owl to heal the baby rock drakes. Which requires a lot of attention at first, but less and less as they age. Also quite a bit of food.

3rd. Which requires no food or feeding, only cryopods and a cryo hospital. Is to just wait until their food is empty and health gets low, then cryopod and put in cryo hospital to build health and food. Rinse and repeat until grown.

*Personally I like to use a mixture of all three and raise them 10 at a time. Can be all healed at once.